aisc-steel-design-guide-07-industrial-buildings

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7 7 
    
Steel Design Guide Steel Design Guide 
Industrial BuildingsIndustrial Buildings
Roofs to Anchor RodsRoofs to Anchor Rods
Second EditionSecond Edition
  
7 7 
    
Steel Design GuideSteel Design Guide
Industrial BuildingsIndustrial Buildings
Roofs Roofs to to Anchor RodsAnchor Rods
JamJames M.es M. FisFisherher
Computerized Computerized Structural Structural Design, Design, Inc.Inc.
Milwaukee, WIMilwaukee, WI
AMERICAN INSTITUTE OF AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.STEEL CONSTRUCTION, INC.
Second EditionSecond Edition
    
Copyright © 2004Copyright © 2004
 by by
American Institute of Steel Construction, Inc.American Institute of Steel Construction, Inc.
 All rights reserv All rights reserved. ed. This book or any part thereof This book or any part thereof 
must not be reproduced in any form without themust not be reproduced in any form without the
written permission of the publisher.written permission of the publisher.
The information presented in this publication has been prepared in accordance with recognizedThe information presented in this publication has been prepared in accordance with recognized
engineering principles and is for general informatiengineering principles and is for general information only. on only. While it is believed to be accurate,While it is believed to be accurate,
this information should not be used or relied upon for any specific application without com-this information should not be used or relied upon for any specific application without com-
 pete petent nt profprofessiessional onal examexaminatination ion and and verification verification of its of its accuracyaccuracy, suitability, and applicability, suitability, and applicability
 by a licensed  by a licensed professional engineerprofessional engineer, designer, or architect. , designer, or architect. The publication of the The publication of the material con-material con-
tained herein is not intended as a representation or warranty on the part of the Americantained herein is not intended as a representation or warranty on the part of the American
InsInstitute of Steel Construction or of any other person named herein, that this informatiotitute of Steel Construction or of any other person named herein, that this information is suit-n is suit-
able for any general or particular use or of freedom from infringement of any patent or patents.able for any general or particular use or of freedom from infringement of any patent or patents.
Anyone making use of this information assumes all liability arising from such use.Anyone making use of this information assumes all liability arising from such use.
Caution must be exercised when relying upon other Caution must be exercised when relying upon other specifications and codes developed by other specifications and codes developed by other 
 bodies and incorporated by refere bodies and incorporated by reference herein since such maternce herein since such material ial may may be be modmodifieified od or ar amendmendeded
from from time ttime to timo time sue subsequebsequent to nt to the pthe printing of thirinting of this edits edition. ion. The InThe Institstitute beute bears no rars no responesponsi-si-
 bility for such material other than to refer to  bility for such material other than to refer to it and incorporate it by reference at it and incorporate it by reference at the time of thethe time of the
initial publication of this edition.initial publication of this edition.
Printed in the United States of AmericaPrinted in the United States of America
First First Printing: Printing: March March 20052005
    
vv
AcknowledgementsAcknowledgements
The author would like to thank Richard C. Kaehler, L.A.The author would like to thank Richard C. Kaehler, L.A.
Lutz, John A. Rolfes, Michael A. West, and Todd AlwoodLutz, John A. Rolfes, Michael A. West, and Todd Alwood
for their contributifor their contributions to this guide. ons to this guide. Special appreciaSpecial appreciation istion is
also given to Carol T. Williams for typing the manuscript.also given to Carol T. Williams for typing the manuscript.
The author also thanks the American Iron and Steel Insti-The author also thanks the American Iron and Steel Insti-
tute for their funding of the tute for their funding of the first edition of this guide.first edition of this guide.
    
viivii
Table of ContentsTable of Contents
PART 1PART 1
1. 1. INDUSTRINDUSTRIALIAL BUILDIBUILDINGS—GENNGS—GENERAL ERAL .......................................................................................................................................................................................................................................1.1
2. 2. LOADING LOADING CONDITICONDITIONS ONS AND AND LOADING LOADING COMBICOMBINANATIONS TIONS ........................................................................................................................................................1........1
3. 3. OWNER-OWNER-ESTESTABLISHEABLISHED D CRITERICRITERIA ...A ............................................................................................................................................................................................................................................2.....2
3.1 3.1 Slab-on-Grade Slab-on-Grade Design Design ...................................................................................................................................................................................................................................................................................2.....2
3.2 3.2 Gib Gib Cranes Cranes .........................................................................................................................................................................................................................................................................................................................2...2
3.3 3.3 Interior VInterior Vehicular Tehicular Traffic raffic ...............................................................................................................................................................................................................................................................................3.3
3.4 3.4 Future Future ExpansionExpansion .....................................................................................................................................................................................................................................................................................................3...3
3.5 3.5 Dust Dust Control/Ease Control/Ease of of Maintenance Maintenance ..........................................................................................................................................................................................................................................3......3
4. 4. ROOF ROOF SYSTEMSYSTEMS...............S.....................................................................................................................................................................................................................................................................................................3........3
4.1 4.1 Steel Steel Deck Deck for for Built-up Built-up or or Membrane Membrane Roofs Roofs ...............................................................................................................................................................................................................4.4
4.2 4.2 Metal Metal Roofs Roofs .......................................................................................................................................................................................................................................................................................................................5.5
4.3 4.3 Insulation Insulationand and Roofing.....Roofing.........................................................................................................................................................................................................................................................................5..........5
4.4 4.4 Expansion Expansion Joints ........Joints ...........................................................................................................................................................................................................................................................................................6.....6
4.5 4.5 Roof Roof Pitch, Pitch, Drainage, Drainage, and and PondingPonding ..........................................................................................................................................................................................................................................7......7
4.6 4.6 Joists Joists and Pand Purlins urlins .....................................................................................................................................................................................................................................................................................................9...9
5. 5. ROOFROOF TRUSSES TRUSSES .........................................................................................................................................................................................................................................................................................................................9...95.1 5.1 General General Design Design and and Economic Economic ConsiderationsConsiderations ................................................................................................................................................................................................10........10
5.2 5.2 Connection Connection Considerations Considerations .............................................................................................................................................................................................................................................................1.......111
5.3 5.3 Truss Truss BracingBracing .........................................................................................................................................................................................................................................................................................................1.......111
5.4 5.4 Erection Erection Bracing .......Bracing .........................................................................................................................................................................................................................................................................................13....13
5.5 5.5 Other Other Considerations Considerations ..................................................................................................................................................................................................................................................................................14......14
6. 6. WWALLALL SYSTEMSYSTEMS...........S...................................................................................................................................................................................................................................................................................................1..........155
6.1 6.1 Field-AssemField-Assembled bled Panels............Panels..........................................................................................................................................................................................................................................................15..........15
6.2 6.2 Factory-AssemFactory-Assembled bled Panels.............Panels.......................................................................................................................................................................................................................................................16....16
6.3 6.3 Precast Precast WWall all Panels ..........Panels ..........................................................................................................................................................................................................................................................................16........16
6.4 6.4 Mansory Mansory WWalls alls ........................................................................................................................................................................................................................................................................................................17....17
6.5 6.5 Girts Girts ..................................................................................................................................................................................................................................................................................................................................17..........17
6.6 6.6 Wind Wind Columns Columns ........................................................................................................................................................................................................................................................................................................19....19
7. 7. FRAMINFRAMING G SCHEMESCHEMES ...S .........................................................................................................................................................................................................................................................................................19........19
7.1 7.1 Braced Braced Frames Frames vs. vs. Rigid Rigid Frames.................Frames..................................................................................................................................................................................................................................19.19
7.2 7.2 HSS HSS Columns Columns vs. vs. W W Shapes .......Shapes ...................................................................................................................................................................................................................................................20......20
7.3 7.3 Mezzanine Mezzanine and and Platform Platform Framing Framing ..........................................................................................................................................................................................................................................20......20
7.4 7.4 Economic Economic Considerations Considerations ................................................................................................................................................................................................................................................................20........20
8. 8. BRACING BRACING SYSTEMSYSTEMSS .....................................................................................................................................................................................................................................................................................................21...21
8.1 8.1 Rigid Rigid Frame Frame SystemsSystems..................................................................................................................................................................................................................................................................................21......21
8.2 8.2 Braced Braced Systems Systems .....................................................................................................................................................................................................................................................................................................22...228.3 8.3 TTemporary emporary Bracing ...........Bracing ...........................................................................................................................................................................................................................................................................24......24
9. 9. COLUMN COLUMN ANCHORAGANCHORAGE ...........E .........................................................................................................................................................................................................................................................................26....26
9.1 9.1 Resisting Resisting TTension ension Forces Forces with with Anchore Anchore RodsRods ..................................................................................................................................................................................................26..........26
9.2 9.2 Resisting Resisting Shear Shear Forces Forces Using Using Anchore Anchore Rods ..............Rods ..........................................................................................................................................................................................31....31
9.3 9.3 Resisting Resisting Shear Shear Forces Forces Through Through Bearing Bearing and and with with Reinforcing Reinforcing Bards Bards ...........................................................................................................................32.32
9.4 9.4 Column Column Anchorage Anchorage Examples Examples (Pinned (Pinned Base) Base) ..................................................................................................................................................................................................34..........34
9.5 9.5 Partial Partial Base Base Fixity Fixity ......................................................................................................................................................................................................................................................................................39..........39
    
viiiviii
10. 10. SERVSERVICEABIICEABILITY CLITY CRITERIRITERIA A ..............................................................................................................................................................................................................................................................39......39
10.1 10.1 ServiceabilitServiceability Criteria for Roof Dy Criteria for Roof Design................esign.............................................................................................................................................................................................................40...40
10.2 10.2 Metal WMetal Wall Panels all Panels .......................................................................................................................................................................................................................................................................................40.........40
10.3 10.3 Precast WPrecast Wall Panels all Panels ....................................................................................................................................................................................................................................................................................40........40
10.4 10.4 Masonry Masonry WWalls ................alls ...................................................................................................................................................................................................................................................................................41.........41
PART 2PART 2
1111. . INTRODUINTRODUCTION CTION ............................................................................................................................................................................................................................................................................................................43........43
11.1 11.1 AISE TAISE Technical Report 13 Building Classiechnical Report 13 Building Classifications fications ...............................................................................................................................................................................43.........43
11.2 11.2 CMAA 70 Crane Classifications CMAA 70 Crane Classifications ............................................................................................................................................................................................................................................43........43
12. 12. FFAATIGUE TIGUE .............................................................................................................................................................................................................................................................................................................................................45...45
12.1 12.1 Fatigue DamageFatigue Damage.....................................................................................................................................................................................................................................................................................................45...45
12.2 12.2 Crane Runway Fatigue ConsiCrane Runway Fatigue Considerations ..derations ........................................................................................................................................................................................................................47......47
13. 13. CRANE INCRANE INDUCED LOADUCED LOADS ADS AND LOAD COND LOAD COMBINAMBINATIONS ........TIONS ...........................................................................................................................................................48.48
13.1 13.1 VVertical Impactertical Impact ........................................................................................................................................................................................................................................................................................................49....49
13.2 13.2 Side ThrustSide Thrust .......................................................................................................................................................................................................................................................................................................................49.49
13.3 13.3 Longitudinal or Longitudinal or TractivTractive Force e Force ...............................................................................................................................................................................................................................................50.........50
13.4 13.4 Crane Stop Forces ..................Crane Stop Forces .............................................................................................................................................................................................................................................................................50.50
13.5 13.5 EccentricitieEccentricities s ........................................................................................................................................................................................................................................................................................................50........50
13.6 13.6 Seismic Loads Seismic Loads ........................................................................................................................................................................................................................................................................................................50....5013.7 13.7 Load Combinations ...............Load Combinations ..........................................................................................................................................................................................................................................................................51...51
14. 14. ROOF SYSTEMS..........ROOF SYSTEMS.............................................................................................................................................................................................................................................................................................................52.52
15. 15. WWALLALL SYSTEMSYSTEMS...........S....................................................................................................................................................................................................................................................................................................5.........522
16. 16. FRAMINFRAMING SYSTEMS............G SYSTEMS...........................................................................................................................................................................................................................................................................................53.53
17. 17. BRACING BRACING SYSTEMSYSTEMSS .....................................................................................................................................................................................................................................................................................................53...53
17.1 17.1 Roof Bracing Roof Bracing ..........................................................................................................................................................................................................................................................................................................53......53
17.2 17.2 WWall Bracing all Bracing ..........................................................................................................................................................................................................................................................................................................54......54
18. 18. CRANE RUNWCRANE RUNWAAY Y DESIGN.....DESIGN.......................................................................................................................................................................................................................................................................55........55
18.1 18.1 Crane Runway Crane Runway Beam Design Beam Design Procedure (ASProcedure (ASD) .........D) .....................................................................................................................................................................................56......56
18.2 18.2 Plate Plate Girders......Girders...........................................................................................................................................................................................................................................................................................................61...61
18.3 18.3 Simple SpaSimple Span vs. Continuous n vs. Continuous Runways ................Runways .............................................................................................................................................................................................................62...62
18.4 18.4 Channel CapsChannel Caps ..........................................................................................................................................................................................................................................................................................................64......64
18.5 18.5 Runway Bracing Concepts....Runway Bracing Concepts.................................................................................................................................................................................................................................................................64...64
18.6 18.6 Crane Stops Crane Stops ...........................................................................................................................................................................................................................................................................................................65.........6518.7 18.7 Crane Rail Crane Rail AttachmentsAttachments ...............................................................................................................................................................................................................................................................................65.65
18.7.1 18.7.1 Hook Hook Bolts Bolts ...................................................................................................................................................................................................................................................................................65.....65
18.7.2 18.7.2 Rail Clips Rail Clips .....................................................................................................................................................................................................................................................................................65.......65
18.7.3 18.7.3 Rail Clamps Rail Clamps .................................................................................................................................................................................................................................................................................66...66
18.7.4 18.7.4 Patented Rail ClipsPatented Rail Clips .............................................................................................................................................................................................................................................................66...66
18.7.5 18.7.5 Design of Design of Rail AttachmeRail Attachments ...................nts ...............................................................................................................................................................................................................66..66
18.8 18.8 Crane Rails Crane Rails and Crane Raiand Crane Rail Jointsl Joints..........................................................................................................................................................................................................................................67......67
19. 19. CRANE CRANE RUNWRUNWAAY Y FFABRICATION ABRICATION AND AND ERECTION ERECTION TOLERANCES TOLERANCES .......................... ............................ ............................ ............................ .........67.........67
20. 20. COLUMN DESCOLUMN DESIGNIGN ..........................................................................................................................................................................................................................................................................................................69......69
20.1 20.1 Base Fixity and Load Sharing .......Base Fixity and Load Sharing .................................................................................................................................................................................................................................................69....69
20.2 20.2 Preliminary Preliminary Design MethodDesign Methodss ............................................................................................................................................................................................................................................................72....7220.2.1 20.2.1 Obtaining TObtaining Trial Moments rial Moments of Inertia for of Inertia for Stepped CStepped Columns olumns .................................................................................................................................74...74
20.2.2 20.2.2 Obtaining TObtaining Trial Moments rial Moments of Inertia for of Inertia for Double ColumnsDouble Columns .................................................................................................................................74.......74
20.3 20.3 Final Design PrFinal Design Procedures (Using ocedures (Using ASD) ..............ASD) ..............................................................................................................................................................................................................74....74
20.4 20.4 Economic CEconomic Considerations onsiderations ................................................................................................................................................................................................................................................................80........80
    
ixix
21. 21. OUTSIDE OUTSIDE CRANES CRANES ........................................................................................................................................................................................................................................................................................................81....81
22. 22. UNDERHUNUNDERHUNG CRAG CRANES NES ....................................................................................................................................................................................................................................................................................82........82
23. 23. MAINTEMAINTENANCE AND REPNANCE AND REPAIR .............AIR ....................................................................................................................................................................................................................................................83...83
24. 24. SUMMARSUMMARYY AND AND DESIGN DESIGN PROCEDUPROCEDURES .................RES ..................................................................................................................................................................................................8.........833
REFERENCES ..........................................................................................................................................................................83REFERENCES ..........................................................................................................................................................................83
APPENDIX A ............................................................................................................................................................................87APPENDIX A ............................................................................................................................................................................87
APPENDIX B ............................................................................................................................................................................89APPENDIX B ............................................................................................................................................................................89
    
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 11
11.. IINNTTRROODDUUCCTTIIOONN
Although the basic structural and architectural componentsAlthough the basic structural and architectural components
of industrial buildings are relatively simple, combining allof industrial buildings are relatively simple, combining allof the elements into a functional economical building canof the elements into a functional economical building can
 be  be a a complex complex task. task. General General guidelines guidelines and and criteria criteria toto
accomplish this task can be stated. The purpose of thisaccomplish this task can be stated. The purpose of this
guide is to provide the industrial building designer withguide is to provide the industrial building designer with
guidelines and design criteria for the design of buildingsguidelines and design criteria for the design of buildings
without cranes, or for buildings with light-to-medium dutywithout cranes, or for buildings with light-to-medium duty
cycle cranes. Part 1 deals with general topics on industrialcycle cranes. Part 1 deals with general topics on industrial
 buildings.  buildings. Part Part 2 2 deals deals with with structures structures containing containing cranes.cranes.
Requirements for seismic detailing for industrial buildingsRequirements for seismic detailing for industrial buildings
have not been addressed in this guide. The designer musthave not been addressed in this guide. The designer must
address any special detailing for seismic conditions.address any special detailing for seismic conditions.
Most industrial buildings primarily serve as an enclosureMost industrial buildings primarily serve as an enclosure
for production and/or storage. The design of industrialfor production and/or storage. The design of industrial
 buildings may seem  buildings may seem logically the logically the province of the province of the structuralstructural
engineerengineer. . It is essential to rIt is essential to realize that most industrial build-ealize that most industrial build-
ings involve much more than structural design. Theings involve much more than structural design. The
designer may assume an expanded role and may be respon-designer may assume an expanded role and may be respon-
sible for site planning, establishing grades, handling surfacesible for site planning, establishing grades, handling surface
drainage, parking, on-site traffic, building aesthetics, and,drainage, parking, on-site traffic, building aesthetics, and,
 perhaps, landscaping.  perhaps, landscaping. Access to Access to rail and rail and the establishmentthe establishment
of proper floor elevations (depending on whether directof proper floor elevations (depending on whether direct
fork truck entry to rail cars is required) are important con-fork truck entry to rail cars is required) are important con-
siderations. siderations. Proper clearances Proper clearances to sidings and to sidings and special atten-special atten-
tion to curved siding and truck grade limitations are alsotion to curved siding and truck grade limitations are also
essential.essential.
22.. LLOOAADDIINNGG CCOONNDDIITTIIOONNS AS ANND LD LOOAADDIINNGG
COMBINATIONSCOMBINATIONS
Loading conditions and load combinations for industrialLoading conditions and load combinations for industrial
 buildings  buildings without without cranes cranes are are well well established established by by buildingbuilding
codes.codes.
Loading conditions are categorized as follows:Loading conditions are categorized as follows:
1.1.  Dead  Dead load:load: This load represents the weight of theThis load represents the weight of the
structure and its components, and is usually expressedstructure and its components, and is usually expressed
in pounds per in pounds per square foot. square foot. In an In an industrial building,industrial building,
the building use and industrial process usually involvethe building use and industrial process usually involve
 permanent  permanent equipment equipment that that is is supported supported by by the the struc-struc-
ture. ture. This equipment This equipment can sometimes can sometimes be represbe representedented
 by a uniform load (known as a collateral load), but the by a uniform load (known as a collateral load), but the
 points  points of attachmentof attachment are usually are usually subjected tsubjected to concen-o concen-
trated loads that require a separate analysis to accounttrated loads that require a separate analysis to account
for the localized effects.for the localized effects.
2.2.  Live load: Live load: This load represents the force imposed onThis load represents the force imposed on
the structure by the occupancy and use of the building.the structure by the occupancy and use of the building.
Building codes give minimum design live loads inBuilding codes give minimum design live loads in
 pounds  pounds per square per square foot, foot, which which vary vary with with the the classifi-classifi-
cation of cation of occupancy aoccupancy and use. nd use. While live While live loads areloads are
expressed as uniform, as a practical matter any occu-expressed as uniform, as a practical matter any occu-
 pancy  pancy loading loading is is inevitably inevitably nonuniform. nonuniform. The The degreedegree
of nonuniformity that is acceptable is a matter of engi-of nonuniformity that is acceptable is a matter of engi-
neering neering judgment. judgment. Some Some building cbuilding codes odes deal deal withwith
nonuniformity of loading by specifying concentratednonuniformity of loading by specifying concentrated
loads in addition to uniform loading for some occu-loads in addition to uniform loading for some occu-
 pancies.  pancies. In an industrial building, In an industrial building, often the use of theoften the use of the
 building may  building may require a live require a live load in excess load in excess of the codeof the code
stated minimum. stated minimum. Often this vaOften this value is spelue is specified by cified by thethe
owner or calculated by the engineerowner or calculated by the engineer. . Also, the loadingAlso, the loading
may be in the form may be in the form of significant concentrated loads asof significant concentrated loads as
in the case of storage racks or machinery.in the case of storage racks or machinery.
3.3. Snow loads:Snow loads: Most codes differentiate between roof Most codes differentiate between roof 
live and live and snow loads. snow loads. Snow loads Snow loads are a are a function of function of 
local climate, roof slope, roof type, terrain, buildinglocal climate, roof slope, roof type, terrain, building
internal temperature, internal temperature, and building and building geometry. geometry. TheseThese
factors may be treated differently by various codes.factors may be treated differently by various codes.
4.4.  Rain loads: Rain loads: These loads are now recognized as a sep-These loads are now recognized as a sep-
arate loading condition. In the past, rain wasarate loading condition. In the past, rain was
accounted for in live load. accounted for in live load. However, some cHowever, some codes haveodes have
a more refined a more refined standard. standard. Rain loading can be a Rain loading can be a func-func-
tion of storm intensity, roof slope, and roof drainage.tion of storm intensity, roof slope, and roof drainage.
There is also the potential for rain on snow in certainThere is also the potential for rain on snow in certain
regions.regions.
5.5. Wind loads:Wind loads: These are well codified, and are a func-These are well codified, and are a func-
tion of local climate conditions, building height, build-tion of local climate conditions, building height, build-
ing geometry and exposure as determined by theing geometry and exposure as determined by the
surrounding environment and terrain. Typically,surrounding environment and terrain. Typically,
they’re based on a 50-year recurrence interval—max-they’re based on a 50-year recurrence interval—max-
imum three-second imum three-second gust. gust. Building codes Building codes account for account for 
increases in local pressure at edges and corners, andincreases in local pressure at edges and corners, and
often have stricter standards for individual compo-often have stricter standards for individual compo-
nents than for the gross nents than for the gross building. building. Wind can apply Wind can apply bothboth
inward and outward forces to various surfaces on theinward and outward forces to various surfaces on the
 building  building exterior exterior and and can can be be affected by affected by size size of of wallwall
openings. openings. Where wind forcWhere wind forces produce oves produce overturning or erturning or 
net upward forces, there must be an adequate counter-net upward forces, there must be an adequate counter-
 balancing structural dead weight  balancing structural dead weight or the structure mor the structure mustust
 be anchored to an  be anchored to an adequate foundation.adequate foundation.
Part 1Part 1
INDUSTRIAL BUILDINGS—GENERALINDUSTRIAL BUILDINGS—GENERAL
    
22 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
6.6.  Earthquake  Earthquake loads:loads: Seismic loads are established bySeismic loads are established by
 building codes and  building codes and are based on:are based on:
a.a. The The degdegree ree of sof seiseismic rmic risk isk 
 b. b. The degree of potential The degree of potential damagedamage
c.c. The poThe possissibilibility of totty of total colal collaplapsese
d.d. The feaThe feasibility osibility of meetinf meeting a giveg a given level on level of protef protec-c-
tiontion
Earthquake loads in building codes are usually equiva-Earthquake loads in building codes are usually equiva-
lent static loads. lent static loads. Seismic loads are Seismic loads are generally a funcgenerally a function of:tion of:
a.a. The geThe geograpographical ahical and geond geological logical locatilocation of ton of thehe
 building building
 b. b. The use of tThe use of the buildinghe building
c.c. The naThe nature oture of the f the buildinbuilding strg structurauctural systel systemm
d.d. The dThe dynamic ynamic propeproperties rties of thof the buie buildinglding
e.e. The dyThe dynamnamic proic properpertieties of the sis of the sitete
f.f. The weThe weight oight of the f the buildinbuilding ang and the d the distribdistribution ution of of 
the weightthe weight
Load combinations are formed by adding the effects of Load combinations are formed by adding the effects of 
loads from each loads from each of the load sourof the load sources cited above. ces cited above. Codes or Codes or 
industry standards often give specific load combinationsindustry standards often give specific load combinations
that must be satisfied. that must be satisfied. It is not always necessary It is not always necessary to consider to consider all loads at full all loads at full intensity. intensity. Also, certain loads are not requiredAlso, certain loads are not required
to be combined at all. to be combined at all. For example, wind need not be For example, wind need not be com-com-
 bined with  bined with seismic. seismic. In some cases In some cases only a portionly a portion of a on of a loadload
must be must be combined with other combined with other loads. loads. When a When a combinationcombination
does not include loads at full intensity it represents a judg-does not include loads at full intensity it represents a judg-
ment as to the probability of simultaneous occurrence withment as to the probability of simultaneous occurrence with
regard to time and intensity.regard to time and intensity.
3.3. OWOWNENER-R-ESESTTABABLILISHSHED ED CRCRITITERERIAIA
Every industrial Every industrial building is building is unique. unique. Each is Each is planned andplanned and
constructed to requirements relating to building usage, theconstructed to requirements relating to building usage, the
 process invol process involved, ved, specific specific owner owner requirements requirements and and prefer-prefer-
ences, ences, site constraints, site constraints, cost, and cost,and building regulations. building regulations. TheThe
 process  process of of design design must must balance balance all all of of these these factors. factors. TheTheowner must play an active role in passing on to the designer owner must play an active role in passing on to the designer 
all requirements specific to the building such as:all requirements specific to the building such as:
1.1. AreArea, ba, bay say sizeize, pl, plan lan layoayout, ut, aisaisle lle locaocatiotion, fn, futuruturee
expansion provisions.expansion provisions.
22.. CClleeaar r hheeiigghhttss..
3.3. RelaRelatiotions bns betweetween fen funcunctiontional aal areareas, prs, produoductioction flon floww,,
acoustical considerations.acoustical considerations.
4.4. ExExteterrioior ar appppeeararaancnce.e.
5.5. MaMateteririalals as and nd fifininishsheses, e, etctc..
6.6. MacMachinehineryry, e, equiquipmepment nt and and stostoragrage e metmethodhod..
77.. LLooaaddss..
There are instances where loads in excess of code mini-There are instances where loads in excess of code mini-
mums are required. mums are required. Such cases call for Such cases call for owner involvement.owner involvement.
The establishment of loading conditions provides for aThe establishment of loading conditions provides for a
structure of structure of adequate adequate strength. strength. AA related set related set of crof criteria areiteria are
needed to establish the serviceability behavior of the struc-needed to establish the serviceability behavior of the struc-
ture. ture. Serviceability design considers Serviceability design considers such topics as such topics as deflec-deflec-
tion, drift, vibration and the relation of the primary andtion, drift, vibration and the relation of the primary and
secondary structural systems and elements to the perform-secondary structural systems and elements to the perform-
ance of nonstructural components such as roofing,ance of nonstructural components such as roofing,
cladding, equipment, etc. Serviceability issues are notcladding, equipment, etc. Serviceability issues are not
strength issues but maintenance and human response con-strength issues but maintenance and human response con-
siderations. siderations. Serviceability criteria arServiceability criteria are discussed e discussed in detail inin detail in
Serviceability Design Considerations for Steel BuildingsServiceability Design Considerations for Steel Buildings
that is part of the AISC Steel Design Guide Series (Fisher,that is part of the AISC Steel Design Guide Series (Fisher,
2003). Criteria taken from the Design Guide are presented2003). Criteria taken from the Design Guide are presented
in this text as appropriate.in this text as appropriate.
As can be seen from this discussion, the design of anAs can be seen from this discussion, the design of an
industrial building requires industrial building requires active owner active owner involvement. involvement. ThisThis
is also illustrated by the following topics: slab-on-gradeis also illustrated by the following topics: slab-on-grade
design, jib cranes, interior vehicular traffic, and futuredesign, jib cranes, interior vehicular traffic, and future
expansion.expansion.
3.3.11 SlSlabab--onon-G-Grarade de DeDesisigngn
One important aspect to be determined is the specific load-One important aspect to be determined is the specific load-
ing to ing to which the which the floor slab floor slab will be will be subjected. subjected. ForkliftForklift
trucks, rack storage systems, or wood dunnage supportingtrucks, rack storage systems, or wood dunnage supporting
heavy manufactured items cause concentrated loads inheavy manufactured items cause concentrated loads in
industrial structures. industrial structures. The important point herThe important point here is that thesee is that these
loadings are nloadings are nonuniform. onuniform. The slab-on-grade The slab-on-grade is thus oftenis thus often
designed as a plate on an elastic foundation subject to con-designed as a plate on an elastic foundation subject to con-
centrated loads.centrated loads.
It is common for owners to specify tIt is common for owners to specify that slabs-on-grade behat slabs-on-grade be
designed for a specific uniform loading (for example, 500designed for a specific uniform loading (for example, 500
 psf).  psf). If If a a slab-on-grade islab-on-grade is s subjected subjected to to a a uniform uniform load, load, itit
will develop no bending will develop no bending moments. moments. Minimum thickness andMinimum thickness and
no reinforcement would be required. The frequency withno reinforcement would be required. The frequency with
which the author has encountered the requirement of designwhich the author has encountered the requirement of designfor a uniform load and the general lack of appreciation of for a uniform load and the general lack of appreciation of 
the inadequacy of such criteria by many owners and plantthe inadequacy of such criteria by many owners and plant
engineers has prompted the inclusion of this topic in thisengineers has prompted the inclusion of this topic in this
guide. guide. Real loads are not uReal loads are not uniform, and an analysis usniform, and an analysis using aning an
assumed nonuniform load or the specific concentrated load-assumed nonuniform load or the specific concentrated load-
ing for the slab ing for the slab is required. is required. An excellent reference An excellent reference for thefor the
design of slabs-on-grade isdesign of slabs-on-grade is  Designing  Designing Floor Floor Slabs Slabs onon
GradeGrade by R by Ringo and ingo and Anderson (Ringo, Anderson (Ringo, 1996). In 1996). In addition,addition,
the designer of slabs-on-grade should be familiar with thethe designer of slabs-on-grade should be familiar with the
ACIACI Guide for Concrete Floor and Slab Guide for Concrete Floor and Slab ConstructionConstruction (ACI,(ACI,
1997), the ACI1997), the ACI Design of Slabs on Grade Design of Slabs on Grade (ACI, 1992).(ACI, 1992).
33..22 JJiib b CCrraanneess
Another loading condition that should be considered is theAnother loading condition that should be considered is the
installation of jib cranes. Often the owner has plans toinstallation of jib cranes. Often the owner has plans to
    
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 33
install such cranes at sinstall such cranes at some future date. ome future date. But since they are aBut since they are a
 purchased  purchased item—often item—often installed installed by by plant plant engineering engineering per-per-
sonnel or the crane manufacturer—the owner may inadver-sonnel or the crane manufacturer—the owner may inadver-
tently neglect them during the design phase.tently neglect them during the design phase.
Jib cranes, which are simply added to a structure, can cre-Jib cranes, which are simply added to a structure, can cre-
ate a myriad of problems, including column distortion andate a myriad of problems, including column distortion and
misalignment, column bending failures, crane runway andmisalignment, column bending failures, crane runway and
crane rail misalignment, and excessive column base shear.crane rail misalignment, and excessive column base shear.
It is essential to know the location and size of jib cranes inIt is essential to know the location and size of jib cranes in
advance, so that columns can be properly designed andadvance, so that columns can be properly designed and
 proper  proper bracing bracing can can be be installed installed if if needed. needed. Columns Columns sup-sup-
 porting jib cranes should be designed to limit the deflection porting jib cranes should be designed to limit the deflection
at the end of the jib boom to boom length divided by 225.at the end of the jib boom to boom length divided by 225.
3.3.33 IIntntererioiorr VVehehicicululararTTrrafaffficic
The designer must establish the exact usage to which theThe designer must establish the exact usage to which the
structure will be structure will be subjected. subjected. Interior vehicular Interior vehicular traffic is traffic is aa
major source of major source of problems in structures. problems in structures. Forklift trucks canForklift trucks can
accidentally buckle the flanges of a column, shear off accidentally buckle the flanges of a column, shear off 
anchor rods in column bases, and damage walls.anchor rods in column bases, and damage walls.
Proper consideration and handling of the forklift truck Proper consideration and handling of the forklift truck 
 problem may include  problem may include some or all some or all of the following:of the following:
1.1. Use Use of mof masoasonry nry or or conconcrecrete ete extexteriorior war walls lls in lin lieu ieu of of 
metal panels. (Often the lowest section of walls ismetal panels. (Often the lowest section of walls is
made of masonry or concrete with metal panels usedmade of masonry or concrete with metal panels used
for the higher section.)for the higher section.)
2.2. InsInstaltallatilation of on of fenfender der posposts (bts (bollaollardsrds) fo) for cor columnlumns ans andd
walls may be required where speed and size of fork walls may be required where speed and size of fork 
trucks are such that a column or load-bearing walltrucks are such that a column or load-bearing wall
could be severely damaged or collapsed upon impact.could be severely damaged or collapsed upon impact.
3.3. Use Use of mof metaetal gul guardardrairails ols or str steel eel plaplate ate adjadjacencent to t to walwalll
elements may be in order.elements may be in order.
44.. CCuurrbbss..
Lines defining traffic lanes painted on factory floors haveLines defining traffic lanes painted on factory floors have
never been successful in preventing structural never been successful in preventing structural damage fromdamage from
interior vehicular interior vehicular operations. operations. The only The only realistic approachrealistic approach
for solving this problem is to anticipate potential for solving this problem is to anticipate potential impact andimpact and
damage and to install barriers and/or materials that candamage and to install barriers and/or materials that can
withstand such abuse.withstand such abuse.
33..44 FFuuttuurre e EExxppaannssioionn
Except where no additional land is available, every indus-Except where no additional land is available, every indus-
trial structure is a candidate for future expansion. Lack of trial structure is a candidate for future expansion. Lack of 
 planning  planning for for such such expansion expansion can can result result in in considerableconsiderable
expense.expense.
When consideration is given to future expansion, thereWhen consideration is given to future expansion, there
are a number of practical considerations that require evalu-are a number of practical considerations that require evalu-
ation.ation.
1.1. The The dirdirectectionions of s of priprincincipal pal and and secsecondondary ary fraframingming
members require studymembers require study. . In some caseIn some cases it may proves it may prove
economical to have a principal frame line along aeconomical to have a principal frame line along a
 building  building edge edge where where expansion expansion is is anticipated anticipated and and toto
design edge beams, columns and foundations for thedesign edge beams, columns and foundations for the
future loads. future loads. If the If the structure is larstructure is large and ge and any futureany future
expansion would require creation of an expansionexpansion would require creation of an expansion
 joint at  joint at a juncture a juncture of existing of existing and future and future construction,construction,
it may be prudent to have that edge of the buildingit may be prudent to have that edge of the building
consist consist of of nonload-bearing nonload-bearing elements. elements. Obviously,Obviously,
foundation design must also include provision for foundation design must also include provision for 
expansion.expansion.
2.2.  Roof Drainage Roof Drainage: An addition which is constructed with: An addition which is constructed with
low points at the junction of the roofs can present seri-low points at the junction of the roofs can present seri-
ous problems in terms of water, ice and snow pilingous problems in terms of water, ice and snow piling
effects.effects.
3.3. LatLateraeral stal stabilbility tity to reo resissist wint wind and and sed seismiismic loc loadiadings ngs isis
often provided by X-bracing in walls or by shear often provided by X-bracing in walls or by shear 
walls. walls. Future expansion may Future expansion may require removal require removal of suchof such
 bracing.  bracing. The The structural structural drawings drawings should should indicate indicate thethe
critical nature of wall bracing, and its location, to pre-critical nature of wall bracing, and its location, to pre-
vent accidental removal. In this context, bracing canvent accidental removal. In this context, bracing can
interfere with many plant production activities and theinterfere with many plant production activities and the
importance of such bracing cannot be importance of such bracing cannot be overemphasizedoveremphasized
to the owner to the owner and plant eand plant engineering personnel. ngineering personnel. Obvi-Obvi-
ously, the location of bracing to provide the capabilityously, the location of bracing to provide the capability
for future expansion without its removal should be thefor future expansion without its removal should be the
goal of the designer.goal of the designer.
3.53.5 DusDust t CoContntrorol/El/Easase e of of MaMainintetenanancncee
In certain buildings (for example, food processing plants)In certain buildings (for example, food processing plants)
dust control is essential. Ideally there should be no horizon-dust control is essential. Ideally there should be no horizon-
tal surfaces on which dust can accumulate. HSS as purlinstal surfaces on which dust can accumulate. HSS as purlins
reduce the number of horizontal surfaces as compared toreduce the number of horizontal surfaces as compared to
C’s, Z’s, or joists. If horizontal surfaces can be tolerated inC’s, Z’s, or joists. If horizontal surfaces can be tolerated in
conjunction with a regular cleaning program, C’s or Z’sconjunction with a regular cleaning program, C’s or Z’s
may be prefemay be preferable to joists. rable to joists. The same thinking The same thinking should beshould be
applied to the selection of main framing members (in other applied to the selection of main framing members (in other 
words, HSS or box sections may be preferable to wide-words, HSS or box sections may be preferable to wide-
flange sections or trusses).flange sections or trusses).
44.. RROOOOF SF SYYSSTTEEMMSS
The roof system is often the most expensive part of anThe roof system is often the most expensive part of an
industrial building (even though walls are more costly per industrial building (even though walls are more costly per 
square foot). square foot). Designing for a Designing for a 20-psf mechanical 20-psf mechanical surchargesurcharge
load when only 10 psf is required adds cost over a largeload when only 10 psf is required adds cost over a large
area.area.
Often the premise guiding the design is that the owner Often the premise guiding the design is that the owner 
will always be hanging new piping or installing additionalwill always be hanging new piping or installing additionalequipment, and a prudent designer will allow for this in theequipment, and a prudent designer will allow for this in the
    
44 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
fies the fies the standardprofile standard profile for 3 for 3 in. deck in. deck as 3DR. as 3DR. AA compari-compari-
son of weights for each profile in various gages shows thatson of weights for each profile in various gages shows that
strength-to-weight ratio is most favorable for wide rib andstrength-to-weight ratio is most favorable for wide rib and
least favorable fleast favorable for narrow ror narrow rib deck. ib deck. In general, the In general, the deck deck 
selection that results in the least weight per ftselection that results in the least weight per ft22 may be themay be the
most economical. However, consideration must also bemost economical. However, consideration must also be
given to the flute width because the igiven to the flute width because the insulation must span thensulation must span the
flutes. flutes. In the northern arIn the northern areas of the U.S., high reas of the U.S., high roof loads andoof loads and
thick insulation generally make the thick insulation generally make the wide rib (B) profile pre-wide rib (B) profile pre-
dominant. dominant. In the South, In the South, low roof loads low roof loads and thinner insula-and thinner insula-
tion make tion make the intermediate the intermediate profile common. profile common. Where veryWhere very
thin insulation is used narrow rib deck may be required,thin insulation is used narrow rib deck may be required,
although this is not a although this is not a common profile. common profile. In general In general the light-the light-
est weight deck consistent with insulation thickness andest weight deck consistent with insulation thickness and
span should be used.span should be used.
system. system. If this If this practice is practice is followed, the owner followed, the owner should beshould be
consulted, and the decision to provide excess capacityconsulted, and the decision to provide excess capacity
should be that of the ownershould be that of the owner. . The design live loads and col-The design live loads and col-
lateral (equipment) loads should be noted on the structurallateral (equipment) loads should be noted on the structural
 plans. plans.
4.4.11 SSteteel Del Dececk fok forr BuBuililt-t-up oup orr MeMembmbrarane Rne Roooofsfs
Decks are commonly 1½ in. deep, but deeper units are alsoDecks are commonly 1½ in. deep, but deeper units are also
available. available. The Steel The Steel Deck Institute (SDI, Deck Institute (SDI, 2001) has 2001) has identi-identi-
fied three standard profiles for 1½ in. steel deck, (narrowfied three standard profiles for 1½ in. steel deck, (narrow
rib, intermediate rib and wide rib) and has published loadrib, intermediate rib and wide rib) and has published load
tables for each profile for thicknesses varying from 0.0299tables for each profile for thicknesses varying from 0.0299
to 0.0478 in. to 0.0478 in. These three profiles, (shown in TThese three profiles, (shown in Table 4.1) NR,able 4.1) NR,
IR, and WR, corresIR, and WR, correspond to the manufacturers’pond to the manufacturers’ designationsdesignations
A, FA, F, and B, respectively, and B, respectively. . The Steel Deck Institute identi-The Steel Deck Institute identi-
Table 4.1 Table 4.1 Steel Deck InstitutSteel Deck Institute Recommended Se Recommended Spans (38)pans (38)
Recommended Maximum Spans for Construction and Recommended Maximum Spans for Construction and Maintenance LoadsMaintenance Loads
Standard 1-1/2 in. and 3 in. Roof DeckStandard 1-1/2 in. and 3 in. Roof Deck
TypeType
SpanSpan
ConditionCondition
SpanSpan
Ft -In.Ft -In.
MaximumMaximum
RecommendedRecommended
Spans Roof DeckSpans Roof Deck
CantileverCantilever
NarrowNarrow
Rib DeckRib Deck
(Old Type A)(Old Type A)
NR22NR22
NR22NR22
11
2 or more2 or more
33′′-10-10″ ″   
44′′-9-9″ ″   
11′′-0-0″ ″   
NR20NR20
NR20NR20
11
2 or more2 or more
44′′-10-10″ ″   
55′′-11-11″ ″   
11′′-2-2″ ″   
NR18NR18
NR18NR18
11
2 or more2 or more
55′′-11-11″ ″   
66′′-11-11″ ″   
11′′-7-7″ ″   
IntermediateIntermediate
Rib DeckRib Deck
(Old Type F)(Old Type F)
IR22IR22
IR22IR22
11
2 or more2 or more
44′′-6-6″ ″   
55′′-6-6″ ″   
11′′-2-2″ ″   
IR20IR20
IR20IR20
11
2 or more2 or more
55′′-3-3″ ″   
66′′-3-3″ ″   
11′′-5-5″ ″   
IR18IR18
IR18IR18
11
2 or more2 or more
66′′-2-2″ ″   
77′′-4-4″ ″   
11′′-10-10″ ″   
Wide RibWide Rib
(Old Type B)(Old Type B)
WR22WR22
WR22WR22
11
2 or more2 or more
55′′-6-6″ ″   
66′′-6-6″ ″    11′′-11-11″ ″   
WR20WR20
WR20WR20
11
2 or more2 or more
66′′-3-3″ ″   
77′′-5-5″ ″   
22′′-4-4″ ″   
WR18WR18
WR18WR18
11
2 or more2 or more
77′′-6-6″ ″   
88′′-10-10″ ″   
22′′-10-10″ ″   
Deep RibDeep Rib
DeckDeck
3DR223DR22
3DR223DR22
11
2 or more2 or more
1111′′-0-0″ ″   
1313′′-0-0″ ″   
33′′-5-5″ ″   
3DR203DR20
3DR203DR20
11
2 or more2 or more
1212′′-6-6″ ″   
1414′′-8-8″ ″   
33′′-11-11″ ″   
3DR183DR18
3DR183DR18
11
2 or more2 or more
1515′′-0-0″ ″   
1717′′-8-8″ ″   
44′′-9-9″ ″   
NOTE: NOTE: SEE SDI SEE SDI LOAD TABLES FOR LOAD TABLES FOR ACTUAL DECK CAPACITIESACTUAL DECK CAPACITIES
    
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 55
In addition to the load, span, and thickness relationsIn addition to the load, span, and thickness relations
established by the load tables, established by the load tables, there are other considerationsthere are other considerations
in the selection of a profile and gage for a given load andin the selection of a profile and gage for a given load and
span. span. First, the Steel Deck First, the Steel Deck Institute limits deflection due toInstitute limits deflection due to
a 200-lb concentrated load at midspan to span divided bya 200-lb concentrated load at midspan to span divided by
240. Secondly, the Steel Deck Institute has published a table240. Secondly, the Steel Deck Institute has published a table
of maximum recommended spans for construction andof maximum recommended spans for construction and
maintenance loads (Table 4.1), and, finally Factory Mutualmaintenance loads (Table 4.1), and, finally Factory Mutual
lists maximum spans for various profiles and gages in itslists maximum spans for various profiles and gages in its
Approval Guide (Table 4.2).Approval Guide (Table 4.2).
Factory Mutual in its Loss Prevention Guide (LPG) 1-28Factory Mutual in its Loss Prevention Guide (LPG) 1-28
 Insulated Steel  Insulated Steel Deck Deck (FM, various dates) provides a stan-(FM, various dates) provides a stan-
dard for attachment of insulation to steel deck. LPG 1-29dard for attachment of insulation to steel deck. LPG 1-29
 Loose Laid  Loose Laid Ballasted Roof Ballasted Roof CoveringsCoverings (FM, various dates)(FM, various dates)
gives a standard for the required weight and distribution of gives a standard for the required weight and distribution of 
 ballast for roofs that  ballast for roofs that are not adhered.are not adhered.
LPG 1-28 requires a side lap fastener between supports.LPG 1-28 requires a side lap fastener between supports.
This fastener prevents adjacent panels from deflecting dif-This fastener prevents adjacent panels from deflecting dif-
ferentially when a load exists at the edge of one panel butferentially when a load exists at the edge of one panel but
not on the edgnot on the edge of the adjacee of the adjacent panel. nt panel. Factory Mutual per-Factory Mutual per-
mits an over span from its published tables of 6 in. (previ-mits an over span from its published tables of 6 in. (previ-
ously an overspan of 10 percent had been allowed) whenously an overspan of 10 percent had been allowed) when
“necessary to accommodate column spacing in some bays“necessary to accommodate column spacing in some bays
of the of the building. building. It should not It should not be considered be considered an originalan original
design parameterdesign parameter.” .” The Steel The Steel Deck Institute recDeck Instituterecommendsommends
that the side laps in cantilevers be fastened at 12 in. on cen-that the side laps in cantilevers be fastened at 12 in. on cen-
ter.ter.
Steel decks can be attached to supports by welds or fas-Steel decks can be attached to supports by welds or fas-
teners, which can be power or pneumatically installed or teners, which can be power or pneumatically installed or 
self-drilling, self-tapping. self-drilling, self-tapping. The SThe Steel Deck teel Deck Institute in Institute in itsits
Specifications and Commentary for Steel Roof Deck Specifications and Commentary for Steel Roof Deck  (SDI,(SDI,
2000) requires a maximum attachment spacing of 18 in.2000) requires a maximum attachment spacing of 18 in.
along supports. along supports. Factory Mutual rFactory Mutual requires the uequires the use of 12se of 12-in.-in.
spacing as spacing as a maximum; this is a maximum; this is more common. more common. The attach-The attach-
ment of roof deck must be sufficient to provide bracing toment of roof deck must be sufficient to provide bracing to
the structural roof members, to anchor the roof to preventthe structural roof members, to anchor the roof to prevent
uplift, and, in many cases, to serve as a diaphragm to carryuplift, and, in many cases, to serve as a diaphragm to carry
lateral loads to the lateral loads to the bracing. bracing. While the standard aWhile the standard attachmentttachment
spacing may be acceptable in many cases, decks designedspacing may be acceptable in many cases, decks designed
as diaphragms may require additional connections.as diaphragms may require additional connections.
Diaphragm capacities can be determined from theDiaphragm capacities can be determined from the
 Diaphragm Design Manual  Diaphragm Design Manual (Steel Deck Institute, 1987)(Steel Deck Institute, 1987)
Manufacturers of metal deck are constantly researchingManufacturers of metal deck are constantly researching
ways to improve section properties with maximum econ-ways to improve section properties with maximum econ-
omy. omy. Considerable diffeConsiderable differences in crences in cost may exist ost may exist betweenbetween
 prices from two suppliers of “identical” deck shapes; there- prices from two suppliers of “identical” deck shapes; there-
fore the designer is urged to research the cost of the deck fore the designer is urged to research the cost of the deck 
system carefusystem carefully. lly. AA few cents few cents per ftper ft22 savings on a large roof savings on a large roof 
area can mean a significant savings to the owner.area can mean a significant savings to the owner.
Several manufacturers can provide steel roof deck andSeveral manufacturers can provide steel roof deck and
wall panels with special acoustical surface treatments for wall panels with special acoustical surface treatments for 
specific building use. specific building use. Properties of Properties of such products such products can becan be
obtained from the obtained from the manufacturers. manufacturers. The owner The owner must specifymust specify
special treatment for acoustical reasons.special treatment for acoustical reasons.
44..22 MMeettaal l RRooooffss
Standing seam roof systems were first introduced in theStanding seam roof systems were first introduced in the
late 1960s, and today many manufacturers produce standinglate 1960s, and today many manufacturers produce standing
seam panels. seam panels. AA difference difference between the between the standing seam standing seam roof roof 
and lap seam roof (through fastener roof) is in the manner and lap seam roof (through fastener roof) is in the manner 
in which two panels in which two panels are joined to are joined to each othereach other. . The seamThe seam
 between  between two two panels panels is is made made in in the the field field with with a a tool tool thatthat
makes a cold-fomakes a cold-formed weather-tight rmed weather-tight joint. joint. (Note: Some pan-(Note: Some pan-
els can be seaels can be seamed without special tools.) med without special tools.) The joint is madeThe joint is made
at the top at the top of the panel. of the panel. The standing seThe standing seam roof is am roof is alsoalso
unique in the manner in which it is attached to the purlins.unique in the manner in which it is attached to the purlins.
The attachment is made with a clip concealed inside theThe attachment is made with a clip concealed inside the
seam. seam. This clip secures This clip secures the panel to the the panel to the purlin and maypurlin and may
allow the panel to move when experiencing thermal expan-allow the panel to move when experiencing thermal expan-
sion or contraction.sion or contraction.
AA continuous single skin membrane recontinuous single skin membrane results after the seamsults after the seam
is made since through-the-roof fasteners have been elimi-is made since through-the-roof fasteners have been elimi-
nated. nated. The elevated seam The elevated seam and single skin and single skin member providesmember provides
a watertight system. a watertight system. The ability of The ability of the roof the roof to experienceto experience
unrestrained thermal movement eliminates damage to insu-unrestrained thermal movement eliminates damage to insu-
lation and structure (caused by temperature effects whichlation and structure (caused by temperature effects which
 built-up and through fastened roofs commonly experience). built-up and through fastened roofs commonly experience).Thermal spacer blocks are often placed between the panelsThermal spacer blocks are often placed between the panels
and purlins in order to insure a consistent thermal barrier.and purlins in order to insure a consistent thermal barrier.
Due to the superiority of the standing seam roof, most man-Due to the superiority of the standing seam roof, most man-
ufacturers are willing to offer considerably longer guaran-ufacturers are willing to offer considerably longer guaran-
tees than those offered on lap seam roofs.tees than those offered on lap seam roofs.
Because of the ability of standing seam roofs to move onBecause of the ability of standing seam roofs to move on
sliding clips, they possess only minimal diaphragm strengthsliding clips, they possess only minimal diaphragm strength
and stiffness. and stiffness. The designer should The designer should assume that the standingassume that the standing
seam roof has no diaphragm capability, and in the case of seam roof has no diaphragm capability, and in the case of 
steel joists specify that sufficient bridging be provided tosteel joists specify that sufficient bridging be provided to
laterally brace the joists under design loads.laterally brace the joists under design loads.
4.4.33 InInsusulalatition on anand Rd Roooofifingng
Due to concern about energy, the use of additional and/or Due to concern about energy, the use of additional and/or 
improved roof improved roof insulation has insulation has become common. become common. Coordina-Coordina-
Table 4.2 Table 4.2 Factory Mutual DaFactory Mutual Data (3)ta (3)
Types 1.5A, 1.5F, 1.5B Types 1.5A, 1.5F, 1.5B and 1.5BI Deck. and 1.5BI Deck. NominalNominal
1½ in. (38mm) de1½ in. (38mm) depth. pth. No stiffening groNo stiffening groovesoves
22g. 22g. 20g. 20g. 18g.18g.
Type 1.5AType 1.5A
Narrow RibNarrow Rib
44′′1010″ ″   
(1.5m)(1.5m)
55′′33″ ″   
(1.6m)(1.6m)
66′′00″ ″   
(1.9m)(1.9m)
Type 1.5FType 1.5F
Intermediate RibIntermediate Rib
44′′1111″ ″   
(1.5m)(1.5m)
55′′55″ ″   
(1.7m)(1.7m)
66′′33″ ″   
(2.0m)(2.0m)
Type 1.5B, BlType 1.5B, Bl
Wide RibWide Rib
66′′00″ ″   
(1.8m)(1.8m)
66′′66″ ″   
(2.0m)(2.0m)
77′′55″ ″   
(2.3m)(2.3m)
    
tion with the mechanical requirements of the building istion with the mechanical requirements of the building is
necessarynecessary. . Generally the use of Generally the use of additional insulation is war-additional insulation is war-
ranted, but there are at least two practicalproblems thatranted, but there are at least two practical problems that
occur as a occur as a result. result. Less heat loss throLess heat loss through the roof reugh the roof results insults in
greater snow and ice bgreater snow and ice build-up and larger snow uild-up and larger snow loads. loads. As aAs a
consequence of the same effect, the roofing is subjected toconsequence of the same effect, the roofing is subjected to
colder temperatures and, for some systems (built-up roofs),colder temperatures and, for some systems (built-up roofs),
thermal movement, which may result in cracking of thethermal movement, which may result in cracking of the
roofing membrane.roofing membrane.
44..44 EExxppaannssioion n JJooininttss
Although industrial buildings are often constructed of flex-Although industrial buildings are often constructed of flex-
ible materials, roof and structural expansion joints areible materials, roof and structural expansion joints are
required when required when horizontal dimensions horizontal dimensions are largeare large. . It is nIt is notot
 possible  possible to to state state exact exact requirements requirements relative relative to to distancesdistances
 between  between expansion expansion joints joints because because of of the the many many variablesvariables
involved, such as ambient temperature during constructioninvolved, such as ambient temperature during construction
and the expected temperature range during the life of theand the expected temperature range during the life of the
 buildings.  buildings. An An excellent excellent reference reference on on the the topic topic of of thermalthermal
expansion in buildings and location of expansion joints isexpansion in buildings and location of expansion joints is
the Federal Construction Council’s Technical Report No.the Federal Construction Council’s Technical Report No.
65,65,  Expansion  Expansion Joints Joints in in BuildingsBuildings (Federal Construction(Federal Construction
Council, 1974).Council, 1974).
The report presents the figure shown herein as FigureThe report presents the figure shown herein as Figure
4.4.1 as a guide for spacing structural expansion joints in4.4.1 as a guide for spacing structural expansion joints in
 beam and column frame buildi beam and column frame buildings based on design temper-ngs based on design temper-
ature change. The report includes data for numerous cities.ature change. The report includes data for numerous cities.
The report gives modifying factors that are applied to theThe report gives modifying factors that are applied to the
allowable building length as appropriate.allowable building length as appropriate.
The report indicates that the curve is directly applicableThe report indicates that the curve is directly applicable
to buildings of beam-and-column construction, hinged atto buildings of beam-and-column construction, hinged at
the base, and the base, and with heated interiors. with heated interiors. When other When other conditionsconditions
 prevail, the followi prevail, the following rules are applicable:ng rules are applicable:
1.1. If If the the builbuildinding wig will bll be he heateated ed onlonly ay and nd will will havhavee
hinged-column bases, use the allowable length ashinged-column bases, use the allowable length as
specified.specified.
2.2. If If the the buibuildinlding wg will ill be be air air conconditiditioneoned ad as ws well ell asas
heated, increase the allowable length 15 percent (if heated, increase the allowable length 15 percent (if thethe
environmental control system will run continuously).environmental control system will run continuously).
3.3. If tIf the bhe builuilding ding will will be ube unhenheateated, dd, decrecreasease the the ale allow-low-
able length 33 percent.able length 33 percent.
4.4. If tIf the bhe builduilding ing will will havhave fie fixed xed colcolumn umn basbases, es, decdecreareasese
the allowable length 15 percent.the allowable length 15 percent.
5.5. If thIf the buie buildinlding wilg will havl have sue substbstantantiallially gry greateater ser stiftiffnefnessss
against lateral displacement in one direction decreaseagainst lateral displacement in one direction decrease
the allowable length 25 percent.the allowable length 25 percent.
When more than one of these design conditions prevailsWhen more than one of these design conditions prevails
in a building, the percentile factor to be applied should bein a building, the percentile factor to be applied should be
the algebraic sum of the adjustment factors of all the vari-the algebraic sum of the adjustment factors of all the vari-
ous applicable conditions.ous applicable conditions.
Regarding the type of structural expansion joint, mostRegarding the type of structural expansion joint, most
engineers agree that the best method is to use a line of dou-engineers agree that the best method is to use a line of dou-
 ble columns  ble columns to provide to provide a complete a complete separation at separation at the joints.the joints.
When joints other than the double column type areWhen joints other than the double column type are
employed, low friction sliding elements, such as shown inemployed, low friction sliding elements, such as shown in
Figure 4.4.2, are generally used. Slip connections mayFigure 4.4.2, are generally used. Slip connections may
66 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
  
 Fig. 4.4.1  Fig. 4.4.1 Expansion Joint Spacing GraphExpansion Joint Spacing Graph
    
 Fig. 4.4.1 Expansion Joint Spacing Graph Fig. 4.4.1 Expansion Joint Spacing Graph
(Taken from F.C.C. Tech. Report No. 65,(Taken from F.C.C. Tech. Report No. 65, Expansion Joints in BuildingsExpansion Joints in Buildings ) )
 Fig. 4.4.2 Beam Expansion Joint  Fig. 4.4.2 Beam Expansion Joint 
  
    
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 77
induce some level of inherent restraint to movement due toinduce some level of inherent restraint to movement due to
 binding or debris buil binding or debris build-up.d-up.
VVery often buildings mery often buildings may be required to ay be required to have firewalls inhave firewalls in
specific locaspecific locations. tions. Firewalls may Firewalls may be rbe required to equired to extendextend
above the roof or they may be allowed to terminate at theabove the roof or they may be allowed to terminate at the
underside of the underside of the roof. roof. Such firewalls become locations Such firewalls become locations for for 
expansion joints. expansion joints. In such cases In such cases the detailing of joints can bethe detailing of joints can be
difficult.difficult.
Figures 4.4.2 through 4.4.5 depict typical details to per-Figures 4.4.2 through 4.4.5 depict typical details to per-
mit limited expansion. mit limited expansion. Additional details are given in arAdditional details are given in archi-chi-
tectural texts.tectural texts.
Expansion joints in the structure should always be car-Expansion joints in the structure should always be car-
ried through the rried through the roofing. oofing. Additionally, dependAdditionally, depending on mem-ing on mem-
 brane type, other joints called area dividers are  brane type, other joints called area dividers are necessary innecessary in
the roof membrane. the roof membrane. These joints are membrane These joints are membrane relief jointsrelief joints
only and do not penetrate the roof deck. only and do not penetrate the roof deck. Area divider jointsArea divider joints
are generally placed at intervals of 150 ft to 250 ft for are generally placed at intervals of 150 ft to 250 ft for 
adhered membranes, at somewhat greater intervals for bal-adhered membranes, at somewhat greater intervals for bal-
lasted membranes, and 100 ft to200 ft in the case of steellasted membranes, and 100 ft to 200 ft in the case of steel
roofs. roofs. Spacing of joints Spacing of joints should be vershould be verified with manufac-ified with manufac-
turer’s turer’s requirements. requirements. The rangThe range of e of movement betweenmovement between
 joints is limited by  joints is limited by the flexibility and the flexibility and movement potential of movement potential of 
the anchorage scheme and, in the case of standing seamthe anchorage scheme and, in the case of standing seam
roofs, roofs, the the clip clip design. design. Manufacturers’Manufacturers’ recommendationsrecommendations
should be consulted should be consulted and followed. and followed. Area dividers can Area dividers can alsoalso
 be  be used used to to divide divide complex complex roofs roofs into into simple simple squares squares andand
rectangles.rectangles.
4.4.55 RoRoof Pof Pititchch, Dr, Draiainanage age and Pnd Ponondidingng
Prior to determining a framing scheme and the direction of Prior to determining a framing scheme and the direction of 
 primary and secondary framing members, it  primary and secondary framing members, it is important tois important to
decide how decide how roof drainage roof drainage is to bis to be accomplished. e accomplished. If theIf the
structure is heated, interior structure is heated, interior roof drains may roof drains may be justified. be justified. For For 
unheated spaces exterior drains and gutters may provide theunheated spaces exterior drains and gutters may provide the
solution.solution.
For some building sites it may not be necessary to haveFor some building sites it may not be necessary to have
gutters and downspouts to control storm water, but their gutters and downspouts to control storm water, but their useuseis generally recommended is generally recommended or required by or required by the ownerthe owner. . Sig-Sig-
nificant operational and hazardous problems can occur nificant operational and hazardous problems can occur 
where water is discharged at the eaves or scuppers in coldwhere water is discharged at the eaves or scuppers in cold
climates, causing icing of ground surfaces and hanging of climates, causing icing of ground surfaces and hanging of 
ice from the rice from the roof edge. oof edge. This is a special This is a special problem at over-problem at over-
head door locations and may occur with or without gutters.head door locations and may occur with or without gutters.
Protection from falling ice must be provided at all buildingProtection from falling ice must be provided at all building
service entries.service entries.
Performance of roofs with positive drainage is generallyPerformance of roofs with positive drainage is generally
good. Due to problems (for example, good. Due to problems (for example, ponding, roofing dete-ponding, roofing dete-
rioration, leaking) that result from poor drainage, the Inter-rioration, leaking) that result from poor drainage, the Inter-
national Building Code, (ICC, 2003) requires a roof slopenational Building Code, (ICC, 2003) requires a roof slope
of at least ¼ in. per ft.of at least ¼ in. per ft.
 Fig. 4.4.3 Joist Expansion Joint  Fig. 4.4.3 Joist Expansion Joint 
 Fig. 4.4.4 Joist Expansion Joint  Fig. 4.4.4 Joist Expansion Joint 
    
Ponding, which is often not understood or is overlooked,Ponding, which is often not understood or is overlooked,
is a phenomenon that may lead to severe distress or partialis a phenomenon that may lead to severe distress or partial
or general collapse.or general collapse.
Ponding as it applies to roof design has two meanings.Ponding as it applies to roof design has two meanings.
To the roofing industry, ponding describes the condition inTo the roofing industry, ponding describes the condition in
which water accumulated in low spots has not dissipatedwhich water accumulated in low spots has not dissipated
within 24 hours of the within 24 hours of the last rainstorm. last rainstorm. Ponding of this naturePonding of this nature
is addressed in roof design by positive roof drainage andis addressed in roof design by positive roof drainage and
control of the deflections control of the deflections of roof framing of roof framing members. members. Pond-Pond-
ing, as an issue in structural engineering, is a load/deflec-ing, as an issue in structural engineering, is a load/deflec-
tion situation, in which, there is incremental accumulationtion situation, in which, there is incremental accumulation
of rainwater in of rainwater in the deflecting structure. the deflecting structure. The purpose of The purpose of aa
 ponding  ponding check check is is to to ensure ensure that that equilibrium equilibrium is is reachedreached
 between  between the the incrementincremental al loading loading and and the the incrementincrementalal
deflection. deflection. This convergence This convergence must occur at a must occur at a level of stresslevel of stress
that is within the allowable value.that is within the allowable value.
The AISC specifications for both LRFD (AISC, 1999)The AISC specifications for both LRFD (AISC, 1999)
and ASD (AISC, 1989) give procedures for addressing theand ASD (AISC, 1989) give procedures for addressing the
 problem  problem of of ponding ponding where where roof roof slopes slopes and and drains drains may may bebe
inadequate. inadequate. The direct method is exThe direct method is expressed in Eq. K2-1 pressed in Eq. K2-1 andand
K2-2 of the specifications. These relations control the stiff-K2-2 of the specifications. These relations control the stiff-
ness of the framing members (primary and secondary) andness of the framing members (primary and secondary) and
deck. This method, however, can produce unnecessarilydeck. This method, however, can produce unnecessarily
conservative conservative results. results. AA more more exact exact method method is pris provided ovided inin
Appendix K of theAppendix K of the LRFD Spe LRFD Specificationcification and in Chapter K inand in Chapter K in
thethe CommentaryCommentary in thein the ASD Specification ASD Specification..
The key to the use of the allowable stress method is theThe key to the use of the allowable stress method is the
calculation of stress in the framing members due to loadscalculation of stress in the framing members due to loads
 present at the initiation of ponding.  present at the initiation of ponding. The difference The difference betweenbetween
0.80.8 F  F  y y and the initial stress is used to establish the requiredand the initial stress is used to establish the required
stiffness of stiffness of the roof the roof framing members. framing members. The initial stressThe initial stress
(“at the initiation of ponding”) is determined from the loads(“at the initiation of ponding”) is determined from the loads
 present at that time.  present at that time. These should include all or most of theThese should include all or most of the
dead load and may include some portion of snow/rain/livedead load and may include some portion of snow/rain/live
load. Technical Digest No. 3 published by the Steel Joistload. Technical Digest No. 3 published by the Steel Joist
Institute SJI (1971) gives some guidance as to the amountInstitute SJI (1971) gives some guidance as to the amount
of snow load that could be used in ponding calculations.of snow load that could be used in ponding calculations.
The amount of accumulated water used is also subject toThe amount of accumulated water used is also subject to
 judgment.  judgment. The AISC ponding criteria only The AISC ponding criteria only applies to roofsapplies to roofs
which lack “sufficient slope towards parts of free drainagewhich lack “sufficient slope towards parts of free drainage
or adequate individual drains to prevent the accumulationor adequate individual drains to prevent the accumulation
of rain waterof rain water...” ...” However, the However, the possibilityof plugged drainspossibility of plugged drains
means that the load at the initiation of ponding couldmeans that the load at the initiation of ponding could
include the depth of impounded water at the level of over-include the depth of impounded water at the level of over-
flow into adjacent bays, or the elevation of overflow drainsflow into adjacent bays, or the elevation of overflow drains
or, over the lip of roof edges oor, over the lip of roof edges or through scuppers. r through scuppers. It is clear It is clear 
from reading the AISCfrom reading the AISC SpecificationSpecification andand CommentaryCommentary thatthat
it is not necessary to include the weight of water that wouldit is not necessary to include the weight of water that would
accumulate after accumulate after the “initiation of pondthe “initiation of ponding.” ing.” Where snowWhere snow
load is used by the code, the designer may add 5 psf to theload is used by the code, the designer may add 5 psf to the
roof load to account for roof load to account for the effect of the effect of rain on snowrain on snow. . Also,Also,
consideration must be given to areas of drifted snow.consideration must be given to areas of drifted snow.
It is clear that judgment must be used in the determina-It is clear that judgment must be used in the determina-
tion of loading “at the initiation of ponding.” It is equallytion of loading “at the initiation of ponding.” It is equally
clear that one hundred percent of the roof design load wouldclear that one hundred percent of the roof design load would
rarely be appropriate for the loading “at the initiation of rarely be appropriate for the loading “at the initiation of 
 ponding.” ponding.”
AA continuously framed or cantilever continuously framed or cantilever system may be moresystem may be more
critical than a simple span system. With continuous fram-critical than a simple span system. With continuous fram-
ing, rotations at points of support, due to roof loads that areing, rotations at points of support, due to roof loads that are
not uniformly distributed, will initiate upward and down-not uniformly distributed, will initiate upward and down-
ward deflections in alternate spans. The water in theward deflections in alternate spans. The water in the
uplifted bays drains into the adjacent downward deflecteduplifted bays drains into the adjacent downward deflected
 bays,  bays, compounding compounding the the effect effect and and causing causing the the downwarddownward
deflected bays to approach the deflected shape of simpledeflected bays to approach the deflected shape of simple
spans. spans. For these systems one For these systems one approach to ponding anapproach to ponding analysisalysis
88 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
  
 Fig. 4.4.5 Truss Expansion Joint  Fig. 4.4.5 Truss Expansion Joint 
    
could be based on simple beam stiffness, although a morecould be based on simple beam stiffness, although a more
refined analysis could be used.refined analysis could be used.
The designer should also consult with the plumbingThe designer should also consult with the plumbing
designer to establish whether or not a controlled flow (water designer to establish whether or not a controlled flow (water 
retention) drain retention) drain scheme is being scheme is being used. used. Such an aSuch an approachpproach
allows the selection of smaller pipes because the water isallows the selection of smaller pipes because the water is
impounded on impounded on the roof the roof and slowly and slowly drained awaydrained away. . ThisThis
intentional impoundment does not meet the AISC criterionintentional impoundment does not meet the AISC criterion
of “drains to prevent the accumulation of rainwater...” andof “drains to prevent the accumulation of rainwater...” and
requires a ponding analysis.requires a ponding analysis.
AA situatiosituation that n that is not is not addresaddressed bsed by buildiy building codng codee
drainage design drainage design is shown in is shown in Figure 4.5.1. Figure 4.5.1. The author hasThe author has
investigated several roof ponding collapses where the accu-investigated several roof ponding collapses where the accu-
mulation of water is greater than would be predicted bymulation of water is greater than would be predicted by
drainage analysis for drainage analysis for the area shown in Figure the area shown in Figure 4.5.1. 4.5.1. As theAs the
water drains towards the eave it finds the least resistance towater drains towards the eave it finds the least resistance to
flow along the parapet to the flow along the parapet to the aperture of the roof. aperture of the roof. Design-Design-
ers are encouraged to pay close attention these situations,ers are encouraged to pay close attention these situations,
and to provide a conservative design for ponding in theand to provide a conservative design for ponding in the
aperture area.aperture area.
Besides rainwater accumulation, the designer should giveBesides rainwater accumulation, the designer should give
consideration to excessive build-up of material on roof sur-consideration to excessive build-up of material on roof sur-
faces (fly ash, and other air borne material) from industrialfaces (fly ash, and other air borne material) from industrial
operations. operations. Enclosed valleys, Enclosed valleys, parallel high- parallel high- and low-aisleand low-aisle
roofs and normal wind flows can cause unexpected build-roofs and normal wind flows can cause unexpected build-
ups and possibly roof overload.ups and possibly roof overload.
44..66 JJooisistts as annd Pd Puurrllininss
AA decision must be made whether to span decision must be made whether to span the long directionthe long direction
of bays with the main beams, trusses, or joist girders whichof bays with the main beams, trusses, or joist girders which
support short span joists or purlins, or to span the shortsupport short span joists or purlins, or to span the short
direction of bays with main framing members which sup-direction of bays with main framing members which sup-
 port longer span joists or purlins.  port longer span joists or purlins. Experience in this regardExperience in this regard
is that spanning the shorter bay dimension with primaryis that spanning the shorter bay dimension with primary
members will provide members will provide the most economical the most economical system. system. How-How-
ever, this decision may not be based solely on economicsever, this decision may not be based solely on economics
 but rather on such factors as  but rather on such factors as ease of erection, future expan-ease of erection, future expan-
sion, direction of crane runs, location of overhead doors,sion, direction of crane runs, location of overhead doors,
etc.etc.
On the use of steel joists or purlins, experience againOn the use of steel joists or purlins, experience again
shows that each shows that each case must be case must be studied. studied. Standard steel Standard steel joistjoist
specifications (SJI, 2002) are based upon distributed loadsspecifications (SJI, 2002) are based upon distributed loads
only. only. Modifications for concentrated Modifications for concentrated loads should be doneloads should be done
in accordance with the SJI Code Of in accordance with the SJI Code Of Standard Practice. Standard Practice. Hot-Hot-
rolled framing members should support significant concen-rolled framing members should support significant concen-
trated loads. trated loads. However, in the However, in the absence of larabsence of large concentratedge concentrated
loads, joist framing can generally be more economical thanloads, joist framing can generally be more economical than
hot rolled framing.hot rolled framing.
Cold-formed C and Z purlin shapes provide another Cold-formed C and Z purlin shapes provide anotheralternative alternative to rto rolled olled WW sections. sections. The The provisions provisions containedcontained
in the American Iron and Steel Institute’sin the American Iron and Steel Institute’s Specification for Specification for 
the Design of Cold-Formed Steel Structural Membersthe Design of Cold-Formed Steel Structural Members
(AISI, 2001) should be used for the design of cold-formed(AISI, 2001) should be used for the design of cold-formed
 purlins.  purlins. Additional economy can be achieved with C and ZAdditional economy can be achieved with C and Z
sections because they can be designed and constructed assections because they can be designed and constructed as
continuous members. continuous members. However, However, progressive faprogressive failure shouldilure should
 be considered  be considered if there if there is a is a possibility for possibility for a loss a loss in continu-in continu-
ity after installation.ity after installation.
Other aspects of the use of C and Z sections include:Other aspects of the use of C and Z sections include:
1.1. Z seZ sectioctions sns ship hip ecoeconomnomicaically lly due due to thto the fae fact tct that hat thetheyy
can be “nested.”can be “nested.”
2.2. Z seZ sectioctions cns can ban be loe loadeaded thd throurough tgh the she sheahear cer cententer; Cr; C
sections cannot.sections cannot.
3.3. On rOn roofoofs wis with ath apprppropropriate iate sloslope a pe a Z seZ sectioction wiln will hal haveve
one principal axis vertical, while a C section providesone principal axis vertical, while a C section provides
this condition only for flat roofs.this condition only for flat roofs.
4.4. ManMany ery erectectors ors indindicaicate thte that laat lap bolp bolted cted connonnectectionions fos for r 
C or Z sections (bolted) are more expensive than theC or Z sections (bolted) are more expensive than the
simple welded down connections for joist ends.simple welded down connections for joist ends.
5.5. At aAt apprpproxioximatemately a ly a 30-30-ft sft span pan lenlength gth C anC and Z sd Z sectectionionss
may cost about the same as a joist for the same loadmay cost about the same as a joist for the same load
 per foot.  per foot. For shorter For shorter spans C spans C and Z and Z sections are sections are nor-nor-
mally less expensive than joists.mally less expensive than joists.
5. ROOF5. ROOF TRUSTRUSSESSES
Primary roof framing for conventionally designed industrialPrimary roof framing for conventionally designed industrial
 buildings  buildings generally generally consists consists of of wide wide flange flange beams, beams, steelsteel
 joist girders, or fabricated truss joist girders, or fabricated trusses. For relatively short spanses. For relatively short spans
of 30- to 40-ft steel beams provide an economical solution,of 30- to 40-ft steel beams provide an economical solution,
 particularly if a multitude of hanging loads are pres particularly if a multitude of hanging loads are present. ent. For For 
spans greater than 40 ft but less than 80-ft spans greater than 40 ft but less than 80-ft steel joist girderssteel joist girders
are often used are often used to support roof to support roof loads. loads. Fabricated steel roof Fabricated steel roof 
trusses are often used for spans gtrusses are often used for spans greater than 80 ft. reater than 80 ft. In recentIn recent
years little has been written about the design of steel roof years little has been written about the design of steel roof 
trusses. Most textbooks addressing the design of trussestrusses. Most textbooks addressing the design of trusses
were written when were written when riveted connections riveted connections were used. were used. TodayToday
welded trusses and field bolted welded trusses and field bolted trusses are used exclusively.trusses are used exclusively.
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 99
SlopeSlope
TypicalTypical
DrainDrainWater Water 
FlowFlow
ParapetParapet
  
 Fig. 4.5.1 Aperture Drainage Fig. 4.5.1 Aperture Drainage
    
Presented in the following paragraphs are concepts andPresented in the following paragraphs are concepts and
 principles that apply  principles that apply to the design to the design of roof trusses.of roof trusses.
5.5.11 GeGeneneraral Desl Design aign and Ecnd Econonomomic Coic Consnsideideraratitiononss
 No absolute  No absolute statements can statements can be made be made about what about what truss con-truss con-
figuration will provide the most economical solution. For afiguration will provide the most economical solution. For a
 particular situati particular situation, however, on, however, the followthe following statementing statements cans can
 be made regarding truss  be made regarding truss design:design:
1.1. SpaSpan-tn-to-do-deptepth rah ratiotios of s of 15 to 15 to 20 g20 geneeneralrally ply provrove to be to bee
economical; however, shipping depth limitationseconomical; however, shipping depth limitations
should be considered so that shop fabrication can beshould be considered so that shop fabrication can be
maximized. maximized. The maximum depth The maximum depth for shipping for shipping is con-is con-
servatively 14 ft. servatively 14 ft. Greater depths Greater depths will require the webwill require the web
members to be field bolted, which will increase erec-members to be field bolted, which will increase erec-
tion costs.tion costs.
2.2. The The lenlength gth betbetweeween sn splicplice pe poinoints its is as also lso limilimited ted byby
shipping shipping lengths. lengths. The The maximum maximum shippable shippable lengthlength
varies according to the destination of the trusses, butvaries according to the destination of the trusses, but
lengths of 80 ft are generally shippable and 100 ft islengths of 80 ft are generally shippable and 100 ft is
often often possible. possible. Because Because maximum maximum available available millmill
length is approximately 70 ft, the distance betweenlength is approximately 70 ft, the distance betweensplice points is normally set at a maximum of 70 ft.splice points is normally set at a maximum of 70 ft.
Greater distances between splice points will generallyGreater distances between splice points will generally
require truss chords to be shop spliced.require truss chords to be shop spliced.
3.3. In gIn geneeneralral, the , the rulrule “de “deepeeper is er is checheapeaper” ir” is trus true; hoe; how-w-
ever, the costs of additional lateral bracing for moreever, the costs of additional lateral bracing for more
flexible truss chords must be carefully examined rela-flexible truss chords must be carefully examined rela-
tive to the cost of larger chords which may require lesstive to the cost of larger chords which may require less
lateral bracing. lateral bracing. The lateral The lateral bracing requbracing requirements for irements for 
the top and bottom chords should be considered inter-the top and bottom chords should be considered inter-
actively while selecting chord actively while selecting chord sizes and types. sizes and types. Partic-Partic-
ular attention should be paid to loads that produceular attention should be paid to loads that produce
compression compression in the in the bottom chord. bottom chord. In this In this conditioncondition
additional chord bracing will most additional chord bracing will most likely be necessary.likely be necessary.
4.4. If pIf possossiblible, see, seleclect trut truss dss deptepths shs so tho that teat tees ces can ban be use useded
for the chorfor the chords rather than ds rather than wide flange shapewide flange shapes. s. TeesTees
can eliminate (or reduce) the need for gusset plates.can eliminate (or reduce) the need for gusset plates.
5.5. HiHighgheer sr strtrenengtgth sh steteelels (s ( F  F  y y = 50 ksi or more) usually= 50 ksi or more) usually
resultsin more efficient truss members.results in more efficient truss members.
6.6. IlluIllustrstrateated in Fd in Figuigures res 5.1.5.1.1 an1 and 5.d 5.1.2 a1.2 are wre web aeb arrarrangenge--
ments that generally provide economical web systems.ments that generally provide economical web systems.
7.7. UtilUtilize ize onlonly a fy a few wew web aeb anglngle sie sizeszes, an, and mad make uke use ose of f 
efficient long leg angles for greater resistance to efficient long leg angles for greater resistance to buck-buck-
ling. ling. Differences in Differences in angle sizes should angle sizes should be recogniza-be recogniza-
 ble.  ble. For instance avoid For instance avoid using an angle using an angle 44××33××¼ and an¼ and an
angle 4angle 4××33××55//1616 in the same truss.in the same truss.
8.8. HSSHSS, wid, wide fle flangange oe or pir pipe spe sectectionions mas may py provrove to e to bebe
more effective web members at some web locations,more effective web members at some web locations,
especially where subsystems are to be supported byespecially where subsystems are to be supported by
web members.web members.
9.9. DeDesisigngns us ussining tg the he AIAISCSC LRFD  LRFD SpecificationSpecification (AISC,(AISC,
1999) will often lead to 1999) will often lead to truss savings when heavy longtruss savings when heavy long
span trusses are rspan trusses are required. equired. This is due to the higher DLThis is due to the higher DL
to LLto LL ratios for theratios for these trussse trusses.es.
10.10. The weThe weight oight of gusf gusset plaset plates, stes, shim plahim plates antes and boltd bolts cans can
 be  be significant significant in in large large trusses. trusses. This This weight weight must must bebe
considered in the design since it often approaches 10considered in the design since it often approaches 10
to 15 percent of the truss weight.to 15 percent of the truss weight.
11.11. If truIf trusses sses are aare analyzenalyzed using d using frame frame analysanalysis compis computer uter 
 programs  programs and and rigid rigid joints joints are are assumed, assumed, secondarysecondary
1010 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
 Fig. 5.1.1 Economical Truss W Fig. 5.1.1 Economical Truss Web Arrangement eb Arrangement 
 Fig. 5.1.2 Economical Truss W Fig. 5.1.2 Economical Truss Web Arrangement eb Arrangement 
    
 bending  bending moments moments will will show show up up in in the the analysis. analysis. TheThe
reader is referred to (Nair, 1988a) wherein it is sug-reader is referred to (Nair, 1988a) wherein it is sug-
gested that so long as these secondary stresses do notgested that so long as these secondary stresses do not
exceed 4,000 exceed 4,000 psi they psi they may be may be neglected. neglected. SecondarySecondary
stresses should not be neglected if the beneficialstresses should not be neglected if the beneficial
effects of continuity are being considered in the effects of continuity are being considered in the designdesign
 process,  process, for for example, example, effective effective length length determination.determination.
The designer The designer must be consistent. must be consistent. That is, if That is, if the jointsthe joints
are considered as pins for the determination of forces,are considered as pins for the determination of forces,
then they should also be considered as pins in thethen they should also be considered as pins in the
design process. design process. The assumption of rThe assumption of rigid joints in someigid joints in some
cases may provide unconservative estimates on thecases may provide unconservative estimates on the
deflection of the truss.deflection of the truss.
12.12. RepetitRepetition ion is is benefbeneficial icial and and econoeconomical. mical. Use Use as as fewfew
different truss depths different truss depths as possible. as possible. It is cheaper to varyIt is cheaper to vary
the chord size as compared to the truss depth.the chord size as compared to the truss depth.
13.13. WidWide flae flange cnge chords hords with gwith gussetussets may s may be nebe necessacessaryry
when significant bending moments exist in the chordswhen significant bending moments exist in the chords
(i.e. subsystems not supported at webs or large dis-(i.e. subsystems not supported at webs or large dis-
tances between webs).tances between webs).
1144.. TThhe e AAIISSCC  Manual of  Manual of Steel ConstructionSteel Construction can providecan provide
some additional guidance on truss design and some additional guidance on truss design and detailing.detailing.
15.15. Design Design and dand detailing etailing of lonof long span g span joists joists and joand joist girist gird-d-
ers shall be in ers shall be in accordance with SJI specifications (SJI,accordance with SJI specifications (SJI,
2002).2002).
5.5.22 CoConnnnecectition on CoConsnsididereratatioionsns
1.1. As mAs mententionioned aed abovbove, te, tee ee chochords rds are are gengeneraerally lly ecoeco--
nomical since nomical since they can they can eliminate gusset eliminate gusset plates. plates. TheThe
designer should examine the connection requirementsdesigner should examine the connection requirements
to determine if the tee stem is in fact long enough toto determine if the tee stem is in fact long enough to
eliminate gusset requirements. The use of a deeper teeeliminate gusset requirements. The use of a deeper tee
stem is generally more economical than addingstem is generally more economical than adding
numerous gusset plates even if this means an additionnumerous gusset plates even if this means an addition
in overall weight.in overall weight.
2.2. BlocBlock shk shear ear reqrequiruiremeements nts and and the the efeffecfective tive arearea ina in
compression should be carefully checked in tee stemscompression should be carefully checked in tee stems
and gussets and gussets (AISC, (AISC, Appendix B). Appendix B). Shear rupturShear rupture of e of 
chord members at panel points should also be investi-chord members at panel points should also be investi-
gated since this can often control wide flange chords.gated since this can often control wide flange chords.
3.3. IntIntermermediediate cate connonnectectors ors (st(stitch itch fasfastenteners ers or for filleillers)rs)
may be required may be required for double for double web members. web members. ExamplesExamples
of intermediate connector evaluation can be found inof intermediate connector evaluation can be found in
the AISCthe AISC Manual  Manual ..
4.4. If wIf wide ide flaflange nge chochords rds are are useused wid with wth wide ide flaflange nge webweb
members it is generally more economical to orient themembers it is generally more economical to orient the
chords with chords with their webs their webs horizontal. horizontal. Gusset plates Gusset plates for for 
the web members can then be either bolted or weldedthe web members can then be either bolted or welded
to the chord flanges. to the chord flanges. To To eliminate the cost of fabricat-eliminate the cost of fabricat-
ing large shim or filler plates for the diagonals, the useing large shim or filler plates for the diagonals, the use
of comparable depth wide flange diagonals should beof comparable depth wide flange diagonals should be
considered.considered.
5.5. WheWhen trun trussesses res requirquire fiee field bold bolted lted joinjoints thts the use use of e of slipslip--
critical bolts in conjunction with oversize holes willcritical bolts in conjunction with oversize holes will
allow for ereallow for erection alignment. ction alignment. Also if standarAlso if standard holesd holes
are used with slip-critical bolts and field “fit-up” prob-are used with slip-critical bolts and field “fit-up” prob-
lems occur, holes can be reamed without significantlylems occur, holes can be reamed without significantly
reducing theallowable bolt shears.reducing the allowable bolt shears.
6.6. For For the ethe end cnd connonnectection ion of trof trussusses, tes, top cop chorhord sed seat tyat typepe
connections should connections should also be also be considered. considered. Seat connec-Seat connec-
tions allow more flexibility in correcting column-trusstions allow more flexibility in correcting column-truss
alignment during erection. alignment during erection. Seats also provSeats also provide for efide for effi-fi-
cient erection and are more stable during erection thancient erection and are more stable during erection than
“bottom bearing” trusses. “bottom bearing” trusses. When seats are When seats are used, a sim-used, a sim-
 ple  ple bottom bottom chord connection chord connection is is recommended to recommended to pre-pre-
vent the truss from rolling during erection.vent the truss from rolling during erection.
7.7. For For symsymmetmetricrical tral trussusses ues use a se a cencenter ter splsplice ice to sto simplimplifyify
fabrication even though forces may be larger than for fabrication even though forces may be larger than for 
an offset splice.an offset splice.
8.8. End End plaplates tes can can proprovidvide efe efficficienient cot comprmpressession sion splicplices.es.
9.9. It is It is oftoften len less ess expexpensensive ive to loto locatcate the the woe work prk poinoint of t of 
the end diagonal at the face of the supporting member the end diagonal at the face of the supporting member 
rather than designing the connection for the eccentric-rather than designing the connection for the eccentric-
ity between the column centerline and the face of theity between the column centerline and the face of the
column.column.
5.3 5.3 TTruss russ BracingBracing
Stability bracing is required at discrete locations where theStability bracing is required at discrete locations where the
designer assumes braced points or where braced points aredesigner assumes braced points or where braced points are
required in the required in the design of the design of the members in the trumembers in the truss. ss. TheseThese
locations are generally at panel points of the trusses and atlocations are generally at panel points of the trusses and at
the ends of the the ends of the web members. web members. To To function properly thefunction properly the
 braces  braces must must have have sufficient sufficient strength strength and and stiffness. stiffness. UsingUsing
standard bracing theory, the brace stiffness required (Factor standard bracing theory, the brace stiffness required (Factor 
of Safety = 2.0) is equal to 4of Safety = 2.0) is equal to 4 P/L P/L, where, where P  P equals the forceequals the force
to be braced andto be braced and  L L equals the unbraced length of the col-equals the unbraced length of the col-
umn. umn. The required brThe required brace force ace force equals 0.004equals 0.004 P  P . As a general. As a general
rule the stiffness requirement will control the design of therule the stiffness requirement will control the design of the
 bracing  bracing unless unless the the bracing bracing stiffness stiffness is is derived derived from from axialaxial
stresses only. Braces that displace due to axial loads onlystresses only. Braces that displace due to axial loads only
are very stiff, and thus the strength requirement will control.are very stiff, and thus the strength requirement will control.
It should be noted that the AISE Technical Report No. 13It should be noted that the AISE Technical Report No. 13
requires a 0.025requires a 0.025 P  P  force force requirement requirement for for bracing. bracing. MoreMorerefined bracing equations are contained in a paper by Lutzrefined bracing equations are contained in a paper by Lutz
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 1111
    
and Fisher titled,and Fisher titled, A A Unified ApprUnified Approach for Stability Bracing oach for Stability Bracing 
 Require Requirementsments (Lutz, 1985). (Lutz, 1985). Requirements for Requirements for truss bottomtruss bottom
chord bracing are discussed in a paper by Fisher titled,chord bracing are discussed in a paper by Fisher titled, TheThe
 Importance  Importance of of TTension ension Chord Chord Bracing Bracing  (Fisher, 1983).(Fisher, 1983).
These requirements do not necessarily apply to long spanThese requirements do not necessarily apply to long span
 joists or joist  joists or joist girders.girders.
Designers are often concerned about the number Designers are often concerned about the number of “out-of “out-
of-straight” trusses that should be considered for a givenof-straight” trusses that should be considered for a given
 bracing  bracing situation. situation. No No definitive definitive rules rules exist; exist; however, however, thethe
Australian Code indicates that no more than seven out of Australian Code indicates that no more than seven out of 
straight members need to be considered. Chen and Tongstraight members need to be considered. Chen and Tong
(1994) (1994) recommend recommend that that columns columns be be considered considered in in thethe
out-of-straight condition whereout-of-straight condition where nn = the total number of = the total number of 
columns columns in in a a story. This story. This equation equation suggests suggests that that trussestrusses
could be could be considered in considered in the bracing the bracing design. design. Thus, if Thus, if tenten
trusses were to be braced, bracing forces could be based ontrusses were to be braced, bracing forces could be based on
four trusses.four trusses.
Common practice is to provide horizontal bracing everyCommon practice is to provide horizontal bracing every
five to six bays to transfer bracing forces to the main forcefive to six bays to transfer bracing forces to the main force
resisting system. resisting system. In this case the brace fIn this case the brace forces should be cal-orces should be cal-
culated based on the number of trusses between horizontalculated based on the number of trusses between horizontal
 bracing. bracing.
AA conveconvenient apprnient approach to the stability bracoach to the stability bracing of trussing of truss
compression chords is discussed in a paper by entitledcompression chords is discussed in a paper by entitled
“Simple Solutions to Stability Problems in the Design“Simple Solutions to Stability Problems in the Design
Office” (Office” (Nair, 1Nair, 1988b). 988b). The solution The solution presented is presented is basedbased
upon the brace stiffness requirements controlled by an X-upon the brace stiffness requirements controlled by an X-
 braced system.  braced system. The paper indicates that The paper indicates that as long as the as long as the hor-hor-
1212 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
StrutStrut
Truss ChordTruss Chord
DiagonalDiagonal
BracingBracing
θθ = 22.5° to 67.5° = 22.5° to 67.5°
θθ
 Fig. 5.3.1 Horizontal X-Bracing Arrangement  Fig. 5.3.1 Horizontal X-Bracing Arrangement 
Design ForcesDesign Forces
(Kips)(Kips)  
Horizontal Truss Web Member ForcesHorizontal Truss Web Member Forces
Member Member Panel Panel Shear Shear Force Force = = (1.414)(Panel (1.414)(Panel Shear)Shear)
C1-D2C1-D2
D1-C2D1-C2 0.006(6X600) 0.006(6X600) = = 21.6 21.6 30.530.5
C2-D3C2-D3
D2-C3D2-C3
0.006(6X800) 0.006(6X800) = = 28.8 28.8 40.740.7
C3-D4C3-D4
D3-C4D3-C4 0.006(6X1000) 0.006(6X1000) = = 36.0 36.0 50.950.9
Horizontal Truss Chord ForcesHorizontal Truss Chord Forces
Member Member Member Member ForcesForces
C1-C2C1-C2
D1-D2D1-D2
21.621.6
C2-C3C2-C3
D2-D3D2-D3
21.6 + 28.8 = 50.421.6 + 28.8 = 50.4
C3-C4C3-C4
D3-D4D3-D4
50.4 + 36 = 86.450.4 + 36 = 86.4
Strut ForcesStrut Forces
Member Member Force Force = = (1.2%)(Ave. (1.2%)(Ave.Chord Chord Force)Force)
A4-B4, A4-B4, E4-F4 E4-F4 12.012.0
B4-C4, B4-C4, D4-E4 D4-E4 24.024.0
C4-D4 36.0C4-D4 36.0
A3-B3, A3-B3, E3-F3 E3-F3 10.810.8
B3-C3, B3-C3, D3-E3 D3-E3 21.621.6
C3-D3 32.4C3-D3 32.4
A2-B2, E2-F2A2-B2, E2-F2
B2-C2, D2-E2B2-C2, D2-E2
C2-D2C2-D2
8.48.4
16.816.8
25.225.2
A1-B1, E1-F1A1-B1, E1-F1
B1-C1, D1-E1B1-C1, D1-E1
C1-D1C1-D1
3.63.6
7.27.2
10.810.8
Note: Note: Forces not sForces not shown are symmhown are symmetricaletrical
nn
nn
    
izontal X-bracing system comprises axially loaded mem-izontal X-bracing system comprises axially loaded mem-
 bers arranged as  bers arranged as shown in shown in Figure 5.3.1, Figure 5.3.1, the bracing the bracing can becan be
designed for 0.6 percent of the truss chord axial load. Sincedesigned for 0.6 percent of the truss chord axial load. Since
two truss chord sections are being braced at each bracingtwo truss chord sections are being braced at each bracing
strut location the strut connections to the trusses must bestrut location the strut connections to the trusses must be
designed for 1.2 percent of the average chord axial load for designed for 1.2 percent of the average chord axial load for 
the two adjacent chords. the two adjacent chords. In the referencIn the reference it is pointed oute it is pointed out
that the bracing forces do not accumulate along the lengththat the bracing forces do not accumulate along the length
of the truss; however, the brace force requirements do accu-of the truss; however, the brace force requirements do accu-
mulate based on the number of trusses considered braced bymulate based on the number of trusses considered braced by
the bracing system.the bracing system.
In addition to stability bracing, top and bottom chordIn addition to stability bracing, top and bottom chord
 bracing may also  bracing may also be required be required to transfer wind to transfer wind or seismic lat-or seismic lat-
eral loads eral loads to the main to the main lateral stability system. lateral stability system. The forceThe force
requirements for the lateral loads must be added to the sta-requirements for the lateral loads must be added to the sta-
 bility force  bility force requirements. requirements. Lateral load bracing Lateral load bracing is placed is placed inin
either the plane of the top chord or the plane of the bottomeither the plane of the top chord or the plane of the bottom
chord, but chord, but generally not generally not in both planes. in both planes. Stability require-Stability require-
ments for the unbraced plane can be transferred to the later-ments for the unbraced plane can be transferred to the later-
ally braced plane by using vertical sway braces.ally braced plane by using vertical sway braces.
EXAMPLE 5.3.1EXAMPLE 5.3.1
Roof Truss Stability BracingRoof Truss Stability Bracing
For the truss system shown in Figure 5.3.2 determine theFor the truss system shown in Figure 5.3.2 determine the
 brace forces in the horizontal bracing  brace forces in the horizontal bracing system. system. Use the pro-Use the pro-
cedure discussed by (Nair, 1988b).cedure discussed by (Nair, 1988b).
Solution:Solution:
Because the diagonal bracing layout as shown in FigureBecause the diagonal bracing layout as shown in Figure
5.3.2 forms an angle of 45 degrees with the trusses, the5.3.2 forms an angle of 45 degrees with the trusses, the
solution used in the paper solution used in the paper by Nair, (by Nair, (1988b) is suitable. 1988b) is suitable. TheThe
 bracing  bracing force force thus thus equals equals 0.6 0.6 percent percent of of the the chord chord axialaxial
load. load. Member forces Member forces are summarized are summarized above.above.
55.4.4 ErEreeccttiioon n BrBraacciinngg
The engineer of record is not responsible for the design of The engineer of record is not responsible for the design of 
erection bracing unless specific contract arrangementserection bracing unless specific contract arrangements
incorporate incorporate this rethis responsibility into sponsibility into the the work. work. However,However,
designdesigners must be familers must be familiar with OSHAiar with OSHA erecterection requirion require-e-
ments (OSHA, 2001) relative to their designs.ments (OSHA, 2001) relative to their designs.
Even though the designer of trusses is Even though the designer of trusses is not responsible for not responsible for 
the erection bracing, the designer should consider sequencethe erection bracing, the designer should consider sequence
and bracing requirements in the design of large trusses inand bracing requirements in the design of large trusses in
order to order to provide the provide the most cost most cost effective effective system. system. LargeLarge
trusses require significant erection bracing not only to trusses require significant erection bracing not only to resistresist
wind and construction loads but also to provide stabilitywind and construction loads but also to provide stability
until all of the until all of the gravity load bragravity load bracing is installed. cing is installed. SignificantSignificant
cost savings can be achieved if the required erection brac-cost savings can be achieved if the required erection brac-
ing is incorporated into the permanent bracing system.ing is incorporated into the permanent bracing system.
Erection is generally accomplished by first connectingErection is generally accomplished by first connecting
two trusses together with strut braces and any additionaltwo trusses together with strut braces and any additional
erection braces to form a stable box system. Additionalerection braces to form a stable box system. Additional
trusses are held in place by the crane or cranes until theytrusses are held in place by the crane or cranes until they
can be “tied off” with strut braces to tcan be “tied off” with strut braces to the already erected sta-he already erected sta-
 ble  ble system. system. Providing Providing the the necessary components necessary components to to facili-facili-
tate this type of erection sequence is essential for a costtate this type of erection sequence is essential for a cost
effective project.effective project.
Additional considerations are as follows:Additional considerations are as follows:
1.1. ColuColumns amns are ure usuasually elly erecrected fted firsirst with t with the lthe lateateral ral brabrac-c-
ing system (see ing system (see Figure 5.4.1). Figure 5.4.1). If top chord If top chord seats areseats are
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 1313
 Fig. 5.3.2 Horizontal Bracing Systen Fig. 5.3.2 Horizontal Bracing Systen
 Fig. 5.4.1 Wa Fig. 5.4.1 Wall Bracing Erection Sequencell Bracing Erection Sequence
1 2 3 4 5 6 71 2 3 4 5 6 7
 A A
BB
CC
DD
EE
FF
HorizontalHorizontal
TrussTruss
Framing PlanFraming Plan
((660000kk)) ((880000kk)) ((11000000kk))
Truss ElevationTruss Elevation
TrussTruss
ChordChord
WebWeb
DiagonalsDiagonals
BracingBracing
StrutsStruts
45°45°
  
TToop p CChhoorrd d SSeeaattss BBoottttoom m BBeeaarriinngg
BracingBracing
installedinstalled
prior toprior to
trusstruss
erection.erection.
ColumnColumn
ColumnColumn
BearingBearing
SeatsSeats
Bracing installedBracing installed
while crane holdswhile crane holds
trusses.trusses.
    
used, the trusses can be quickly positioned on top of used, the trusses can be quickly positioned on top of 
the columns, braced to one another.the columns, braced to one another.
Bottom chord bearing trusses require that additionalBottom chord bearing trusses require that additional
stability bracing be installed at ends of trusses whilestability bracing be installed at ends of trusses while
the cranes the cranes hold the trussehold the trusses in place. s in place. This can sThis can slowlow
down the erection sequence.down the erection sequence.
2.2. SincSince maemany iny indundustrstrial bial builduildings ings reqrequiruire cle clear ear spaspans,ns,
systems are often designed as rigid systems are often designed as rigid frames. By design-frames. By design-
ing rigid frames, erection is facilitated, in that, theing rigid frames, erection is facilitated, in that, the
sidewall columns are stabilized in the plane of thesidewall columns are stabilized in the plane of the
trusses once the trusses are adequately anchored to thetrusses once the trusses are adequately anchored to the
columns. columns. This scheme This scheme may require may require larger larger columnscolumns
than a braced frame system; however, savings in brac-than a braced frame system; however, savings in brac-
ing and erection time can often offset these costs.ing and erection time can often offset these costs.
3.3. WiWide de flaflange nge beabeams, ms, HSS HSS or or pippipe see sectioctions sns shouhould bld bee
used to laterally brace large trusses at key locationsused to laterally brace large trusses at key locations
during erection because of greater stiffness. Steelduring erection because of greater stiffness. Steel
 joists  joists can be can be used; however, used; however, two two notes of notes of caution caution areare
advised:advised:
a.a. ErectiErection bracon bracing string strut forcut forces muses must be prot be provided tovided to
the joist manufacturer; and it must be made clear the joist manufacturer; and it must be made clear 
whether joist bridging and roof deck will be inwhether joist bridging and roof deck will be in
 place  place when twhen the erection he erection forces are forces are present. present. LargeLarge
angle top chords in joists may be required to con-angle top chords in joists may be required to con-
trol the joist slenderness ratio so that it does nottrol the joist slenderness ratio so that it does not
 buckle while serving  buckle while serving as the erection as the erection strut.strut.
 b. b. Joists are Joists are often not often not fabricated to fabricated to exact lengths exact lengths andand
long slotted holes are generally provided in joistlong slotted holes are generally provided in joist
seats. seats. Slotted holes Slotted holes for for bolted bracbolted bracing membersing members
should be avoided because of possible slippage.should be avoided because of possible slippage.
Special coordination with the joist manufacturer isSpecial coordination with the joist manufacturer is
required to eliminate the slots and to required to eliminate the slots and to provide a suit-provide a suit-
able joist for bracing. able joist for bracing. In addition the joists must beIn addition the joists must be
at the job site when the erector wishes to erect theat the job site when the erector wishes to erect the
trusses.trusses.
4.4. WiWind fnd forcorces oes on the n the trutrussesses durs during eing erecrection tion can can be cbe con-on-
siderable. See Design Loads on Structures Duringsiderable. See Design Loads on Structures During
Construction, ASCE 37-02, ASCE (2002), for detailedConstruction, ASCE 37-02, ASCE (2002), for detailed
treatment of wind forces on buildings during construc-treatment of wind forces on buildings during construc-
tion. The AISC Code of Standard Practice states thattion. The AISC Code of Standard Practice states that
“These temporary supports shall be sufficient to“These temporary supports shall be sufficient to
secure the bare Structural Steel framing or any portionsecure the bare Structural Steel framing or any portion
thereof against loads that are likely to be encounteredthereof against loads that are likely to be encountered
during erection, including those due to wind and thoseduring erection, including those due to wind and those
that result from erection operations.” The projectedthat result from erection operations.” The projected
area of all of the truss and other roof framing membersarea of all of the truss and other roof framing members
can be significant, and in some cases the wind forcescan be significant, and in some cases the wind forces
on the unsided structure are actually larger than thoseon the unsided structure are actually larger than those
after the structure is enclosed.after the structure is enclosed.
5.5. AA swsway fay frarame ime is nos normrmalally rly reqequiruired ied in orn ordeder to pr to plulumbmb
the trusses during erecthe trusses during erection. tion. These sway frames shThese sway frames shouldould
normally occur every fourth or fifth baynormally occur every fourth or fifth bay. . An elevationAn elevation
view of such a truss is shown in Figure 5.4.2. Theseview of such a truss is shown in Figure 5.4.2. These
frames can be incorporated into the bottom chordframes can be incorporated into the bottom chord
 bracing  bracing system. system. Sway Sway frames frames are are also also often often used used toto
transfer forces from one chord level to another as dis-transfer forces from one chord level to another as dis-
cussed earlier. In these cases the sway frames must cussed earlier. In these cases the sway frames must notnot
only be designed for stability forces, but also theonly be designed for stability forces, but also the
required load transfer forces.required load transfer forces.
55.5.5 OtOthheerr CCoonnssidideerraattiioonnss
1.1. CamCamber ber larlarge cge clealear spr span tran trussusses to es to accaccommommodaodate dte deadead
load deflections. load deflections. The fabricator The fabricator accomplishes this accomplishes this byby
either adjusting the length of the web members in theeither adjusting the length of the web members in the
truss and keeping the top chord segments straight or truss and keeping the top chord segments straight or 
 by curving the top chord.  by curving the top chord. TeTees can generally be easilyes can generally be easily
curved during assembly whereas wide flange sectionscurved during assembly whereas wide flange sections
may require cambermay require cambering prior to aing prior to assembly. ssembly. If signifi-If signifi-
cant top chord pitch is provided and if the bottomcant top chord pitch is provided and if the bottom
chord is chord is pitched, camber pitched, camber may not may not be required. be required. TheThe
engineer of record is responsible for providing the fab-engineer of record is responsible for providing the fab-
ricator with the anticipated dead load deflection andricator with the anticipated dead load deflection and
special cambering requirements.special cambering requirements.
The designer must carefully consider the truss deflec-The designer must carefully consider the truss deflec-
tion and camber adjacent to walls, or other portions of tion and camber adjacent to walls, or other portions of 
the structure where stiffness changes cause variationsthe structure where stiffness changes cause variations
in deflections. in deflections. This is This is particularly true particularly true at buildingat building
endwalls, where differential deflections may damageendwalls, where differential deflections may damage
continuous purlins or connections.continuous purlins or connections.
2.2. ConConnecnection tion detdetailails ths that cat can aan accoccommommodatdate tee tempemperatratureure
changes are changes are generally necessarygenerally necessary. . Long span Long span trussestrusses
that are fabricated at one temperature and erected at athat are fabricated at one temperature and erected at a
significantly different temperature can grow or shrink significantly different temperature can grow or shrink 
significantly.significantly.
1414 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
PurlinPurlin
Bottom Chord BracingBottom Chord Bracing
   C   C
     T   T
  r  r  u  u
  s  s
  s  s
   L   L    C   C
     T   T
  r  r  u  u
  s  s
  s  s
   L   L
Sway BraceSway BraceFig. 5.4.2  Fig. 5.4.2 Sway FrameSway Frame
    
3.3. RooRoof def deck dck diapiaphrahragm sgm stretrengtngth anh and std stiffiffnesness ars are coe com-m-
monly used for strength and stability bracing for joimonly used for strength and stability bracing for joists.sts.
The diaphragm capabilities must be carefully evalu-The diaphragm capabilities must be carefully evalu-
ated if it is to be used for bracing of large clear spanated if it is to be used for bracing of large clear span
trusses.trusses.
For a more comprehensive treatment of erection bracingFor a more comprehensive treatment of erection bracing
design, readdesign, read Serviceability Design Considerations for Serviceability Design Considerations for Steel Steel 
 Buildings Buildings, (Fisher , (Fisher and Wesand West, 2003).t, 2003).
66.. WWAALLL SL SYYSSTTEEMMSS
The wall system can be chosen for a variety of reasons andThe wall system can be chosen for a variety of reasons and
the cost of the wall the cost of the wall can vary by as much as a factor of can vary by as much as a factor of three.three.
WWall systems all systems include:include:
1.1. FiFieleld asd assesembmbleled med metatal pal panenelsls..
2.2. FaFactctorory y asassesembmbleled d memetatal pl pananelels.s.
3.3. PrPrececasast ct cononcrcretete e papanenelsls..
4.4. MaMasosonrnry wy walalls (ls (papart rt or or fufull hll heieighght)t)..
AA particular wall system may be particular wall system may be selected over others selected over others for for 
one or more specific reasons including:one or more specific reasons including:
11.. CCoosstt..
22.. AAppppeeaarraannccee..
33.. EEaasse e oof f eerreecctitioonn..
44.. SSppeeeed od of ef erreecctitioonn..
5.5. InInsusulalatiting ng prpropoperertitieses..
6.6. FiFirre ce cononsisidederratatioionns.s.
7.7. AcAcououststicical cal cononsisidederaratitionons.s.
8.8. EaEase se of of mamainintetenanancnce/e/clecleananining.g.
9.9. EaEase se of of fufututure re exexpapansnsioion.n.
1010.. DurDurababiliility oty of ff fininisish.h.
1111.. MaiMaintentenannance ce conconsidsideraerationtions.s.
Some of these factors will be discussed in the followingSome of these factors will be discussed in the following
sections on specific systems. Other factors are not discussedsections on specific systems. Other factors are not discussed
and require evaluation on a case-by-case basis.and require evaluation on a case-by-case basis.
6.6.11 FiFieleld-d-AsAsssememblbled Ped Pananelelss
Field assembled panels consist of an outer skin element,Field assembled panels consist of an outer skin element,
insulation, and in some cases an inner insulation, and in some cases an inner liner panel. liner panel. The pan-The pan-
els vary in material thickness and are normally galvanized,els vary in material thickness and are normally galvanized,galvanized prime painted suitable for field painting, or pre-galvanized prime painted suitable for field painting, or pre-
finished galvanized. Corrugated aluminum liners are alsofinished galvanized. Corrugated aluminum liners are also
used. used. When aluminum materials When aluminum materials are used are used their compatibil-their compatibil-
ity with steel supports should be verified with the manufac-ity with steel supports should be verified with the manufac-
turer since aluminum may cause corrosion of steel. Whenturer since aluminum may cause corrosion of steel. When
an inner liner is used, some form of hat section interior sub-an inner liner is used, some form of hat section interior sub-
girts are generally provided for stiffness. The insulation isgirts are generally provided for stiffness. The insulation is
typically fiberglass or typically fiberglass or foam. foam. If the inner liner If the inner liner sheet is usedsheet is used
as the vapor barrier all joints and edges should be sealed.as the vapor barrier all joints and edges should be sealed.
Specific advantages of field assembled wall panelsSpecific advantages of field assembled wall panels
include:include:
1.1. RaRapipid d ererecectition on of of papanenelsls..
2.2. GooGood cod cost cst compompetitetitionion, wit, with a h a larlarge nge numbumber oer of maf manu-nu-
facturers and contractors being capable of erectingfacturers and contractors being capable of erecting
 panels. panels.
3.3. QuicQuick ank and ed easy asy panpanel rel repleplaceacemenment in t in the the eveevent ont of f 
 panel damage. panel damage.
4.4. OpeOpeninnings fgs for or doodoors rs and and windwindows ows that that can can be cbe creareatedted
quickly and quickly and easily.easily.
5.5. PanPanels els thathat art are lige lightwehtweighight, st, so tho that hat heaveavy eqy equipuipmenment ist isnot required for not required for erection. erection. Also large foundAlso large foundations andations and
heavy spandrels are not required.heavy spandrels are not required.
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 1515
  
 Fig. 6.1.1 W Fig. 6.1.1 Wall Thermal Break Detail all Thermal Break Detail 
    
6.6. AcoAcoustustic sic surfurface ace tretreatmatment ent thathat cat can be n be addadded eed easiasily toly to
interior panel wall at reasonable cost.interior panel wall at reasonable cost.
AA disadvantage of disadvantage of field assembled panels field assembled panels in high humid-in high humid-
ity environments can be the ity environments can be the formation of frost or condensa-formation of frost or condensa-
tion on the inner liner when insulation is placed onlytion on the inner liner when insulation is placed only
 between the  between the subgirt lines. subgirt lines. The metal-to-metal The metal-to-metal contact (out-contact (out-
side sheet-subgirt-inside sheet) should be broken to reduceside sheet-subgirt-inside sheet) should be broken to reduce
thermal brthermal bridging. idging. AA detail that detail that has has been been used sused successfullyuccessfully
is shown in Figure 6.1.1. is shown in Figure 6.1.1. Another option may be to provideAnother option may be to provide
rigid insulation between the rigid insulation between the girt and liner girt and liner on one side. on one side. InIn
any event, the wall should be evaluated for thermal trans-any event, the wall should be evaluated for thermal trans-
mittance in mittance in accordance accordance with (ASHRAE, with (ASHRAE, 1989).1989).
6.6.22 FaFactctorory-y-AsAssesembmbleled d PaPanenelsls
Factory assembled panels generally consist of interior liner Factory assembled panels generally consist of interior liner 
 panels, exterior metal panels and insulation.  panels, exterior metal panels and insulation. Panels provid-Panels provid-
ing various insulating values are available from severaling various insulating values are available from several
manufacturers. manufacturers. These These systems systems are are generally generally proprietaryproprietary
and must be designed according to manufacturer’s recom-and must be designed according to manufacturer’s recom-
mendations.mendations.
The particular advantages of these factory-assembledThe particular advantages of these factory-assembled
 panels are: panels are:
1.1. PanPanels aels are lire lightwghtweigeight anht and red requirquire no he no heaveavy cry craneanes fos for r 
erection, no large foundations or heavy spandrels.erection, no large foundations or heavy spandrels.
2.2. PanPanels els can can havhave a e a harhard sud surfarface ce inteinteriorior lir linerner..
3.3. PanPanel sel side lide lap fap fastasteneeners ars are nre normormally ally conconceacealed led propro--
ducing a “clean” appearance.ducing a “clean” appearance.
4.4. DocDocumeumentented pand panel peel perforformarmance cnce charharactacterierististics decs deterter--
mined by test or experience may be available frommined by test or experience may be available from
manufacturers.manufacturers.
Disadvantages offactory-assembled panels include:Disadvantages of factory-assembled panels include:
1.1. OncOnce a ce a choihoice oce of paf panel nel has has beebeen man made, de, futfuture ure expexpan-an-
sions may effectively require use of the same panel tosions may effectively require use of the same panel to
match color and profile, thus competition is essentiallymatch color and profile, thus competition is essentially
eliminated.eliminated.
2.2. EreErectiction pon procroceduedures res usuusually ally reqrequiruire ste startarting ing in oin onene
corner of a structure and proceeding to tcorner of a structure and proceeding to the next corner.he next corner.
Due to the interlocking nature of the panels it may beDue to the interlocking nature of the panels it may be
difficult to add openings in the wall.difficult to add openings in the wall.
3.3. ClosClose ate attententiotion to cn to cooroordindinatiation oon of def detailtails ans and told toler-er-
ances with collateral materials is required.ances with collateral materials is required.
4.4. TheThermarmal chl changanges ies in pan panel snel shahape mape may be my be more ore appappararentent..
6.6.33 PrPrececasast t WWalall l PaPanenelsls
Precast wall panels for industrial buildings could utilize onePrecast wall panels for industrial buildings could utilize one
or more of a variety of panel types including:or more of a variety of panel types including:
11.. HHoolllloow cw coorre se slalabbss..
22.. DDoouubbllee--TT sseeccttiioonnss..
3.3. SiSite te cacast st titiltlt-u-up p papanenelsls..
4.4. FaFactctorory y ccasast t papanenelsls..
Panels can be either load bearing or nonload bearing andPanels can be either load bearing or nonload bearing and
can be obtained in a wide variety of finishes, textures andcan be obtained in a wide variety of finishes, textures and
colors. colors. Also, panels may Also, panels may be of be of sandwich construction andsandwich construction and
contain rigid insulation between two layers of concrete.contain rigid insulation between two layers of concrete.
Such insulated panels can be composite or noncomposite.Such insulated panels can be composite or noncomposite.
Composite panels normally have a positive concrete con-Composite panels normally have a positive concrete con-
nection between nection between inner and inner and outer concreouter concrete layers. te layers. TheseThese
 panels  panels are are structurally structurally stiff and stiff and are are good good from from an an erectionerection
 point  point of of view view but but the the “positive” “positive” connection between connection between inner inner 
and outer layers may lead and outer layers may lead to exterior surface cracking whento exterior surface cracking when
the panels are the panels are subjected to a subjected to a temperature diffetemperature differential. rential. TheThe
direct connection can also provide a path for thermal bridg-direct connection can also provide a path for thermal bridg-
ing.ing.
True sandwich panels connect inner and outer concreteTrue sandwich panels connect inner and outer concrete
layers with flexible layers with flexible metal ties. metal ties. Insulation is expoInsulation is exposed at allsed at all
 panel edges.  panel edges. These panels are These panels are more difficult to more difficult to handle andhandle and
erect, but normally perform well.erect, but normally perform well.
Precast panels have advantages for use in industrialPrecast panels have advantages for use in industrial
 buildings: buildings:
1.1. AA hahard rd susurfrfacace ie is ps prorovidvided ed insinside ide anand od out.ut.
2.2. ThesThese pe paneanels ls proproducduce ae an an archrchitecitecturaturally lly “cle“clean”an”
appearance.appearance.
3.3. PanPanels hels have ave inhinhereerent fint fire rre resiesistastance nce chacharacracterteristiistics.cs.
4.4. IntIntermermediediate ate girgirts ts are are usuusuallally ny not ot reqrequiruired.ed.
5.5. Use Use of lof load oad beabearinring pag panelnels cas can eln eliminiminate ate extexterierior or 
framing and reduce cost.framing and reduce cost.
6.6. PanPanels els proprovidvide ae an en excexcellenllent st sounound bd barrarrierier..
Disadvantages of precast wall panel systems include:Disadvantages of precast wall panel systems include:
1.1. MatMatchiching cng coloolors ors of paf panelnels in s in futfuture ure expexpansansion ion may may bebe
difficult.difficult.
2.2. ComComposposite ite sansandwicdwich ph paneanels hls have ave “co“cold sld spotpots” s” withwith
 potential condensation problems  potential condensation problems at panel edges.at panel edges.
3.3. AdAddinding wag wall oll opepeniningngs cas can be n be difdiffificucult.lt.
4.4. PanPanels els havhave poe poor sor sounound abd absorsorptiption con charharactacterierististics.cs.
1616 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
    
5.5. FouFoundandatiotions ans and gnd gradrade bee beams ams may may be hbe heaveavier ier thathan fon for r 
other panel systems.other panel systems.
6.6. HeaHeavievier ear eave sve strutruts arts are ree requiquired red for for stesteel frel frame same strutruc-c-
tures than for other systems.tures than for other systems.
7.7. HeaHeavy vy cracranes nes are are reqrequiruired ed for for panpanel eel erecrectiontion..
8.8. If pIf paneanels arls are use used aed as los load bad bearearing eing elemlementents, exs, expanpansiosionn
in the future could present problems.in the future could present problems.
9.9. ClosClose ate attentention tion to toto tolerlerancances aes and dnd detaetails tils to coo coordordinainatete
divergent trades are required.divergent trades are required.
10.10. Added Added dead dead weight weight of walof walls can ls can affeaffect seisct seismic demic design.sign.
66..44 MMaassoonnrry y WWaallllss
Use of masonry walls in industrial buildings is common.Use of masonry walls in industrial buildings is common.
Walls can be load bearing or non-load bearing.Walls can be load bearing or non-load bearing.
Some advantages of the use of masonry construction are:Some advantages of the use of masonry construction are:
1.1. AA hahard rd susurfrfacace is e is prprovovidided ed ininsiside de anand od outut..
2.2. MasMasonronry way walls hlls have ave inhinhereerent fint fire rre resiesistastance nce chacharacracterter--
istics.istics.
3.3. IntIntermermediediate ate girgirts ts are are usuusually ally not not reqrequiruired.ed.
4.4. Use Use of lof load oad beabearinring wag walls lls can can elimeliminainate ete extexteriorior frr fram-am-
ing and reduce cost.ing and reduce cost.
5.5. MasMasonronry wy walls alls can can serserve ve as as sheshear ar walwalls tls to bro braceace
columns and resist lateral loads.columns and resist lateral loads.
6.6. WWalls alls proproducduce a fle a flat fiat finisnish, reh, resulsultinting in an eg in an ease oase of bof bothth
maintenance and dust control considerations.maintenance and dust control considerations.
Disadvantages of masonry include:Disadvantages of masonry include:
1.1. MasMasonronry hy has as comcomparparativatively ely low low matemateriarial bl bendendinging
resistance. resistance. WWalls are normally aalls are normally adequate to resist nordequate to resist nor--
mal wind loads, but interior impact loads can causemal wind loads, but interior impact loads can cause
damage.damage.
2.2. FouFoundandatiotions mns may bay be hee heaviavier ter than han for for metmetal waal wall pall panelnel
construction.construction.
3.3. SpeSpeciacial col consinsiderderatioation is n is reqrequiruired in ed in the the use use of mof masoasonrynry
ties, depending on whether the masonry is erectedties, depending on whether the masonry is erected
 before or after the  before or after the steel frame.steel frame.
4.4. BuilBuildingdings in ss in seiseismic rmic regiegions ons may rmayrequequire ire spespeciacial reil rein-n-
forcing and added dead weight may increase seismicforcing and added dead weight may increase seismic
forces.forces.
66..55 GGiirrttss
Typical girts for industrial buildings are hot rolled channelTypical girts for industrial buildings are hot rolled channel
sections or cold-formed light gage sections or cold-formed light gage C or Z sections. C or Z sections. In someIn some
instances HSS are used to eliminate the need for compres-instances HSS are used to eliminate the need for compres-
sion flange bracing. In recent years, cold-formed sectionssion flange bracing. In recent years, cold-formed sections
have gained popularity because of their low cost. As men-have gained popularity because of their low cost. As men-
tioned earlier, cold-formed Z sections can be easily lappedtioned earlier, cold-formed Z sections can be easily lapped
to achieve continuity resulting in further weight savings andto achieve continuity resulting in further weight savings and
reduced deflections, Z sections also ship economically.reduced deflections, Z sections also ship economically.
Additional advantages of cold-formed sections comparedAdditional advantages of cold-formed sections compared
with rolled girt shapes are:with rolled girt shapes are:
1.1. MetMetal wal wall pall paneanels cls can ban be ate attactached hed to cto coldold-fo-formermed gid girtsrts
quickly and inexpensively using self-drilling fasteners.quickly and inexpensively using self-drilling fasteners.
2.2. ThThe use use oe of saf sag rg rodods is s is ofofteten non not ret reququirireded..
Hot-rolled girts are often used when:Hot-rolled girts are often used when:
1.1. CorCorrosrosive eive envinvironronmenments dts dictaictate thte the use use of e of thicthicker ker secsec--
tions.tions.
2.2. ComCommon mon colcold-fd-formormed sed sectectionions do s do not not havhave se sufufficficienientt
strength for a given span or load condition.strength for a given span or load condition.
3.3. GirGirts wits will rll receeceive sive subsubstantantial tial abuabuse fse from rom opeoperatrationions.s.
4.4. DesDesignigners ers are are unfunfamiamiliar liar with with the the avaavailabilabilitility ay andnd
 properties of cold-formed sections. properties of cold-formed sections.
Both hot-rolled and cold-formed girts subjected to pres-Both hot-rolled and cold-formed girts subjected to pres-
sure loads are normally considered laterally braced by thesure loads are normally considered laterally braced by the
wall sheathing. Negative moment regions in continuouswall sheathing. Negative moment regions in continuous
cold-formed girt systems are typically considered laterallycold-formed girt systems are typically considered laterally
 braced  braced at at inflection inflection points points and and at at girt girt to to column column connec-connec-
tions. Continuous systems have been analyzed by assum-tions. Continuous systems have been analyzed by assum-
ing:ing:
1.1. AA sisingngle le prprisismamatic tic sesectctioion n thrthrououghghouout.t.
2.2. AA dodoububle le momomement nt of of ineinertrtia ia cocondnditiition on witwithin hin thethe
lapped section of the cold-formed girt.lapped section of the cold-formed girt.
Research indicates that an analytical model assuming aResearch indicates that an analytical model assuming a
single prismatic section is closer to experimentally deter-single prismatic section is closer to experimentally deter-
mined behavior (Robertson, 1986).mined behavior (Robertson, 1986).
The use of sag rods is generally The use of sag rods is generally required to maintain hor-required to maintain hor-
izontal alignment of hot-rolled sections. The sag rods areizontal alignment of hot-rolled sections. The sag rods are
often assumed to provide lateral restraint against bucklingoften assumed to provide lateral restraint against buckling
for suction loads. for suction loads. When used as braWhen used as bracing, the sag rods mustcing, the sag rods must
 be  be designed designed to to take take tension tension in in either either the the upward or upward or down-down-
ward direction. ward direction. The paneling is The paneling is assumed to proassumed to provide lateralvide lateral
support for support for pressure pressure loads. loads. Lateral stability fLateral stability for the or the girtgirt
 based on this assumption is  based on this assumption is checked using Chapter F of thechecked using Chapter F of the
AISCAISC SpecificationSpecification..
The typical design procedure for hot-rolled girts is as fol-The typical design procedure for hot-rolled girts is as fol-
lows:lows:
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 1717
    
1.1. SeleSelect thct the gire girt sizt size bae based sed on pon presressursure loae loads, ds, assassuminumingg
full flange lateral support.full flange lateral support.
2.2. CheCheck thck the see seleclected ted girgirt fot for sar sag rog rod red requiquiremrementents bas basedsed
on deflections and bending stresses about the weak on deflections and bending stresses about the weak 
axis of the girt.axis of the girt.
3.3. CheCheck tck the ghe girt firt for sor suctuction ion loaloads uds usinsing Chg Chaptapter F er F of tof thehe
AISC Specification.AISC Specification.
4.4. If tIf the ghe girt iirt is ins inadeadequaquate, te, incincrearease ise its sts size ize or aor add sdd sagag
rods.rods.
5.5. CheCheck ck the the girgirt ft for or serservicviceabeabilitility ry requequireiremenments.ts.
6.6. CheCheck tck the she sag rag rods ods for for thetheir air abilibility to ty to resresist ist the the twistwistt
of the girt due to the of the girt due to the suction loads. suction loads. The sag rod andThe sag rod and
siding act to provide the torsional brace.siding act to provide the torsional brace.
Cold-formed girts should be designed in accordance withCold-formed girts should be designed in accordance with
the provisions of the American Iron and Steel Institutethe provisions of the American Iron and Steel Institute
 North  North American American Specification Specification for for the the Design Design of of Cold-Cold-
 Formed  Formed Steel Steel Structural Structural MembersMembers (AISI, 2001). Many(AISI, 2001). Many
manufacturers of cold-formed girts provide design assis-manufacturers of cold-formed girts provide design assis-
tance, and offer load span tables to aid design.tance, and offer load span tables to aid design.
Section C3.1.2 “Lateral Buckling Strength” of the AISISection C3.1.2 “Lateral Buckling Strength” of the AISI
SpecificationSpecification  provides  provides a a means means for for determinindetermining g cold-cold-
formed girt strength when the compression flange of the girtformed girt strength when the compression flange of the girt
is attached to sheeting (fully braced) or when discrete pointis attached to sheeting (fully braced) or when discrete point
 braces (sag rods) are used.  braces (sag rods) are used. For lapped systems, For lapped systems, the sum of the sum of 
the moment capacities of the two lapped girts is normallythe moment capacities of the two lapped girts is normally
assumed to resist the negative moment over the support.assumed to resist the negative moment over the support.
For full continuity to exist, a lap length on each side of theFor full continuity to exist, a lap length on each side of the
column support should be equal to at least 1.5 times the girtcolumn support should be equal to at least 1.5 times the girt
depth (Robertson, depth (Robertson, 1986). 1986). Additional provisions aAdditional provisions are givenre given
in Section C3 for strength considerations relative to shear,in Section C3 for strength considerations relative to shear,
web crippling, and combined bending and shear.web crippling, and combined bending and shear.Section C3.1.3 “Beams with One FlangeAttached toSection C3.1.3 “Beams with One Flange Attached to
Deck or Sheathing” provides a simple procedure to designDeck or Sheathing” provides a simple procedure to design
cold-formed girts cold-formed girts subjected to subjected to suction loading. suction loading. The basicThe basic
equation for the determination of the girt strength is:equation for the determination of the girt strength is:
 M  M nn == RS  RS ee F  F  y y
The values ofThe values of R R are shown below:are shown below:
S S ee == Elastic Elastic sectiosection modulun modulus, of ths, of the effe effective ective sectiosection,n,
calculated with the extreme compression or tensioncalculated with the extreme compression or tension
fiber atfiber at F  F  y y..
 F  F  y y == SpeSpecifcified minied minimum yiimum yield steld stresress.s.
Other restrictions relative to insulation, girt geometry,Other restrictions relative to insulation, girt geometry,
wall panels, fastening systems between wall panels andwall panels, fastening systems between wall panels and
girts, etc. are discussed in the AISI specifications.girts, etc. are discussed in the AISI specifications.
1818 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
Simple Span C- or Z-Section R Simple Span C- or Z-Section R ValuesValues
Depth Depth Range, Range, in. in. Profile Profile RR
dd ≤≤  6.5 6.5 C C or or Z Z 0.700.70
6.5 < d6.5 < d ≤≤  8.5 8.5 C C or or Z Z 0.650.65
8.5 < d8.5 < d ≤≤  11.5 11.5 Z Z 0.500.50
8.5 < d8.5 < d ≤≤  11.5 11.5 C C 0.400.40
 Fig. 6.6.1  Fig. 6.6.1 Wind Column Reaction Load TWind Column Reaction Load Transferransfer Fig. 6.6.2 Fig. 6.6.2 Wind Column Reaction Load TWind Column Reaction Load Transfer ransfer 
    
It should also be mentioned that consideration should beIt should also be mentioned that consideration should be
given to tolerance differences between erected columns andgiven to tolerance differences between erected columns and
girts. The use of slotted holes in girt to column attachmentsgirts. The use of slotted holes in girt to column attachments
is often required.is often required.
66..66 WWiinnd d CCoolluummnnss
When bay spacings exceed 30 ft additional intermediateWhen bay spacings exceed 30 ft additional intermediate
columns may be required to provide for economical girtcolumns may be required to provide for economical girt
design. design. Two Two considerations that should be emphasconsiderations that should be emphasized are:ized are:
1.1. SufSufficficienient brt braciacing ong of thf the wie wind cnd coluolumns mns to ato accoccommommo--
date wind suction loads is needed. This is normallydate wind suction loads is needed. This is normally
accomplished by bracing the interior flanges of theaccomplished by bracing the interior flanges of the
columns with angles that connect to the girts.columns with angles that connect to the girts.
2.2. ProProper per attattentention ion shoshould uld be pbe paid aid to tto the the top cop connonnectectionionss
of the of the columns. columns. For intermediate For intermediate sidewall columns,sidewall columns,
secondary roof framing members must be provided tosecondary roof framing members must be provided to
transfer the wind reaction at the top of the column intotransfer the wind reaction at the top of the column into
the roof the roof bracing sysbracing system. tem. Do not Do not rely on rely on “trickle the-“trickle the-
ory” (in ory” (in other words, other words, “a force “a force will find a will find a way toway to
trickle out trickle out of the of the structure”). structure”). AA positive and positive and calcula-calcula-
 ble  ble system system is is necessary necessary to to provide provide a a traceable traceable loadload path (in other  path (in other words, Figure 6.6.1). words, Figure 6.6.1). Bridging systemsBridging systems
or bottom chord extension on joists can be used to dis-or bottom chord extension on joists can be used to dis-
sipate these forces, but the stresses in the system mustsipate these forces, but the stresses in the system must
 be  be checked. checked. If If the the wind wind columns columns have have not not beenbeen
designed for axial load, a slip connection would bedesigned for axial load, a slip connection would be
necessary at the top of the column.necessary at the top of the column.
Small wind reactions can be transferred from the windSmall wind reactions can be transferred from the wind
columns into the roof diaphragm system as shown incolumns into the roof diaphragm system as shown in
Figure 6.6.2.Figure 6.6.2.
Allowable values for attaching metal deck to structuralAllowable values for attaching metal deck to structural
members can be obtained from screw manufacturers.members can be obtained from screw manufacturers.
Allowable stresses in welds to metal deck can be deter-Allowable stresses in welds to metal deck can be deter-
mined from tmined from the American Whe American Welding Societyelding Society Standard Speci-Standard Speci-
 fication for W fication for Welding Sheet Steeelding Sheet Steel in Structurl in Structureses, (AWS, 1998), (AWS, 1998)
or from the or from the AISI specifications (AISI, 2001). AISI specifications (AISI, 2001). In addition toIn addition to
determining the fastener requirements to transfer the con-determining the fastener requirements to transfer the con-
centrated load into the diaphragm, the designer must alsocentrated load into the diaphragm, the designer must also
check the roof diaphrcheck the roof diaphragm for its strength and stifagm for its strength and stiffness. fness. ThisThis
can be accomplished by using the procedures contained incan be accomplished by using the procedures contained in
the Steel Deck Institute’sthe Steel Deck Institute’s Diaphragm Design M Diaphragm Design Manual anual (SDI,(SDI,
2001).2001).
77.. FFRRAAMMIINNGG SSCCHHEEMMEESS
The selection of “the best” framing scheme for an industrialThe selection of “the best” framing scheme for an industrial
 building w building without ithout cranes is cranes is dependent on dependent on numerous consid-numerous consid-
erations, and often depends erations, and often depends on the owner’s on the owner’s requirements. requirements. ItIt
may not be possible to give a list of rules by which the bestmay not be possible to give a list of rules by which the best
such scheme such scheme can be assurcan be assured. ed. If “best” If “best” means low initialmeans low initial
cost, then the owner may face major expenses in the futurecost, then the owner may face major expenses in the future
for operational expenses for operational expenses or problems with expansor problems with expansion. ion. ExtraExtra
dollars invested at the outset reduce potential future costs.dollars invested at the outset reduce potential future costs.
The economy of using of long span vs. short span joistsThe economy of using of long span vs. short span joists
and purlins has been mentioned previously in this guide.and purlins has been mentioned previously in this guide.
This section expands on the selection of the main framingThis section expands on the selection of the main framing
system. No attempt has been made to evaluate foundationsystem. No attempt has been made to evaluate foundation
costs. costs. In general, if a deeIn general, if a deep foundation system (for p foundation system (for example,example,
 piles  piles or or drilled drilled piers) piers) is is required, required, longer longer bay bay spacings spacings arearenormally more economical.normally more economical.
The consideration of bay sizes must include not only roof The consideration of bay sizes must include not only roof 
and frame factors but also the wall system. The cost of largeand frame factors but also the wall system. The cost of large
girts and thick wall panels may cancel the savings antici-girts and thick wall panels may cancel the savingsantici-
 pated if the  pated if the roof system alone is roof system alone is considered.considered.
Additional aids in the design of efficient framing detailsAdditional aids in the design of efficient framing details
can be found incan be found in  Detailing  Detailing for for Steel Steel ConstructionConstruction (AISC,(AISC,
2002).2002).
7.7.11 BrBracaced ed FrFramames es vsvs. R. Rigigid id FrFramameses
The design of rigid frames is explained in numerous text-The design of rigid frames is explained in numerous text-
 books  books and and professional professional journals journals and and will will not not be be coveredcovered
here; however, a few concepts will here; however, a few concepts will be presented concerningbe presented concerning
the selection of a braced versus a rigid the selection of a braced versus a rigid frame structural sys-frame structural sys-
tem. tem. There are There are several situations for several situations for which a rigid fwhich a rigid framerame
system is likely to be superior.system is likely to be superior.
1.1. BraBraced ced fraframes mes may may reqrequiruire bre braciacing ing in bon both tth the whe wallsalls
and rand roof. oof. Bracing Bracing frequently frequently interferes interferes with plantwith plant
operations and operations and future expansion. future expansion. If either If either considera-considera-
tion is important, a rigid frame structure may be thetion is important, a rigid frame structure may be the
answer.answer.
2.2. The The brabracincing of g of a ra roof oof syssystem tem can can be be accaccompomplishlisheded
through X-bracing or a rthrough X-bracing or a roof diaphragm. oof diaphragm. In either caseIn either case
the roof becomes a large horizontal beam spanningthe roof becomes a large horizontal beam spanning
 between the  between the walls or walls or bracing which bracing which must transmit must transmit thethe
lateral loads lateral loads to the to the foundations. foundations. For large For large span tospan to
width ratios (greater than 3:1) the bracing require-width ratios (greater than 3:1) the bracing require-
ments bments become ecome excessive. excessive. AA building with building with dimensionsdimensions
of 100 ft by 300 ft with potential future expansion inof 100 ft by 300 ft with potential future expansion in
the long direction may best be suited for rigid framesthe long direction may best be suited for rigid frames
to minimize or eliminate bracing that would interfereto minimize or eliminate bracing that would interfere
with future changes.with future changes.
Use of a metal building system requires a strong interac-Use of a metal building system requires a strong interac-
tion between the designer and the metal building manufac-tion between the designer and the metal building manufac-
turer. That’s because of much of the detailing processturer. That’s because of much of the detailing process
related to design is provided by the manufacturer, and therelated to design is provided by the manufacturer, and the
options open to the buyer may reflect the limits of the man-options open to the buyer may reflect the limits of the man-
ufacturer’s standard product line and details.ufacturer’s standard product line and details.
Experience has shown that there are occasions whenExperience has shown that there are occasions when
 braced frame construction  braced frame construction may prove tmay prove to be o be more economi-more economi-
cal than either standard metal building systems or specialcal than either standard metal building systems or special
rigid frame construction when certain sacrifices on flexibil-rigid frame construction when certain sacrifices on flexibil-
ity are accepted.ity are accepted.
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 1919
    
77..22 HHSSS CS Coolluummnns vs vss.. WW ShapesShapes
The design of columns in industrial buildings includes con-The design of columns in industrial buildings includes con-
siderations that do not apply to other types of structures.siderations that do not apply to other types of structures.
Interior columns can normally be braced only at the top andInterior columns can normally be braced only at the top and
 bottom, thus square HSS columns are desirable due t bottom, thus square HSS columns are desirable due to their o their 
equal stiffness equal stiffness about both principal axes. about both principal axes. Difficult connec-Difficult connec-
tions with HSS members can be eliminated in single-storytions with HSS members can be eliminated in single-story
frames by placing the beams over the tops frames by placing the beams over the tops of the HSS. of the HSS. ThusThus
a simple to fabricate cap plate detail with bearing stiffenersa simple to fabricate cap plate detail with bearing stiffeners
on the girder web may be designed. Other advantages of on the girder web may be designed. Other advantages of 
HSS columns include the fact that they require less paintHSS columns include the fact that they require less paint
than equivalentthan equivalent WW shapes, and they are pleasing aestheti-shapes, and they are pleasing aestheti-
cally.cally.
WW shapes may be more economical than HSS for exterior shapes may be more economical than HSS for exterior 
columns for the following reasons:columns for the following reasons:
1.1. The The walwall syl systestem (gm (girtirts) ms) may bay be use used ted to bro brace ace the the weaweak k 
axis of the column. axis of the column. It should be noted It should be noted that a stiffener that a stiffener 
or brace may be required for the column if the insideor brace may be required for the column if the inside
column flange is in compression and the girt connec-column flange is in compression and the girt connec-
tion is assumed to provide a braced point in design.tion is assumed to provide a braced point in design.
2.2. BenBendinding mg momeoments nts due due to to wind wind loaloads ds prepredomidominatnatee
about one axis.about one axis.
3.3. It is eIt is easiasier to er to fraframe gime girt cort connennectioctions to ns to a Wa W shashape thpe thanan
to a HSS section. to a HSS section. Because HSS have Because HSS have no flanges, extrano flanges, extra
clip angles are required to connect girts.clip angles are required to connect girts.
7.3 7.3 Mezzanine Mezzanine and and Platform Platform FramingFraming
Mezzanines and platforms are often required in industrialMezzanines and platforms are often required in industrial
 buildings. The type of usage dictates design considerations. buildings. The type of usage dictates design considerations.
For proper design the designer needs to consider the fol-For proper design the designer needs to consider the fol-
lowing design parameters:lowing design parameters:
11.. OOccccuuppaannccy y oor r UUssee..
2.2. DeDesisign Logn Loadads (Us (Unifnifororm and Cm and Cononcecentntrarateted)d)..
3.3. DeDeflflecectitioon n CrCrititereriaia..
44.. SSuurrffaacce e TTyyppee..
a.a. RaiRaised sed patpattertern n plaplate.te.
 b. b. Smooth plate.Smooth plate.
c.c. ConConcrecrete cte compomposiosite ste slablab..
d.d. ConConcrecrete non-te non-comcomposposite slabite slab..
e.e. Hollow Hollow core core slabs slabs (toppe(topped or d or untoppuntopped).ed).
ff.. PPlylywowooodd..
5.5. GuaGuard rard rail reqil requiruiremeementsnts, incl, includiuding reng removmovabable secle sectiotions.ns.
66.. FFuuttuurre Ee Exxppaannssiioonn..
7.7. VVibibraratitioon n CoContntrrolol..
8.8. LaLateteraral l StStababiliility ty ReReququiriremeementsnts..
7.4 7.4 Economic Economic ConsiderationsConsiderations
As previously mentioned, bay sizes and column spacing areAs previously mentioned, bay sizes and column spacing are
often dictated by the function of the building. Economics,often dictated by the function of the building. Economics,
however, shouldalso be considered. In general, as bay sizeshowever, should also be considered. In general, as bay sizes
increase, the weight of the horizontal framing increases.increase, the weight of the horizontal framing increases.
This will mean additional cost unless offset by savings inThis will mean additional cost unless offset by savings in
foundations or erfoundations or erection. ection. Studies have Studies have indicated that squareindicated that square
or slightly rectangular bays usually result in more econom-or slightly rectangular bays usually result in more econom-
ical structures.ical structures.
In order to evaluate various framing schemes, a prototypeIn order to evaluate various framing schemes, a prototype
general merchandise structure was analyzed using variousgeneral merchandise structure was analyzed using various
spans and component structural elements. The structure wasspans and component structural elements. The structure was
a 240-fta 240-ft ×× 240-ft building with a 25-ft eave height. The t240-ft building with a 25-ft eave height. The totalotal
2020 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
    
roof load was 48 psf, and beams withroof load was 48 psf, and beams with F  F  y y = 50 ksi were used.= 50 ksi were used.
Plastic analysis and design was used. Columns were HSSPlastic analysis and design was used. Columns were HSS
with a yield strength of 46 ksi.with a yield strength of 46 ksi.
Variables in the analysis were:Variables in the analysis were:
1.1. JoJoisist st spapansns: : 2525, 3, 30, 0, 4040, 5, 50 0 anand d 60 60 ftft..
22.. GGiirrddeer r ssppaannss,, WW sections: sections: 25, 30, 425, 30, 40, 48 an0, 48 and 60 fd 60 ft.t.
Cost data were determined from several fabricators. TheCost data were determined from several fabricators. The
data did not include sales tax or shipping costs. The studydata did not include sales tax or shipping costs. The study
yielded several interesting conclusions for engineersyielded several interesting conclusions for engineers
involved in industrial building design.involved in industrial building design.
An examination of the tabular data shows that the mostAn examination of the tabular data shows that the most
economical framing scheme was the one with beams span-economical framing scheme was the one with beams span-
ning 30 ft and joists spanning 40 ft.ning 30 ft and joists spanning 40 ft.
Another factor that may be important is that Another factor that may be important is that for the larger for the larger 
 bays (greater  bays (greater than than 30 ft) 30 ft) normal girt normal girt construction becomesconstruction becomes
less efficient using C or Z sections without intermediateless efficient using C or Z sections without intermediate
“wind columns” being added. For the “wind columns” being added. For the 240-ft240-ft ×× 240-ft build-240-ft build-
ing being considered, wind columns could add $0.10 per ing being considered, wind columns could add $0.10 per 
square ft of roof to the cost. Interestingly, if the buildingsquare ft of roof to the cost. Interestingly, if the building
were 120 ftwere 120 ft ×× 120 ft, the addition of intermediate wind120 ft, the addition of intermediate wind
columns would add $0.20 per ftcolumns would add $0.20 per ft
22
 because the smaller build- because the smaller build-ing has twice the perimeter to area ratio as the larger structure.ing has twice the perimeter to area ratio as the larger structure.
Additional economic and design considerations are asAdditional economic and design considerations are as
follows:follows:
1.1. WheWhen stn steel jeel joisoists arts are use used in ed in the rthe roof oof fraframing ming it is git is gen-en-
erally more economical to span the joists in the longerally more economical to span the joists in the long
direction of the bay.direction of the bay.
2.2. K seK serieries jos joists ists are are mormore ee econconomicomical tal than han LH jLH joisoists;ts;
thus an attempt should be made to limit spans to thosethus an attempt should be made to limit spans to those
suitable for K joists.suitable for K joists.
3.3. For 3For 30-f0-ft to 40t to 40-ft -ft baybays, efs, efficficienient frt framinaming mag may cony consissistt
of continuous or double-cantilevered girders sup-of continuous or double-cantilevered girders sup-
 ported by columns in  ported by columns in one direction and joists sone direction and joists spanningpanning
the other direction.the other direction.
4.4. If tIf the ghe girdirders ers are are concontinutinuousous, pl, plastastic dic desiesign ign is ofs oftenten
used. used. Connection costs foConnection costs for continuous memberr continuous members mays may
 be higher  be higher than for than for cantilever design; cantilever design; however, a plas-however, a plas-
tically designed continuous system will have superior tically designed continuous system will have superior 
 behavior  behavior when when subjected subjected to to unexpected unexpected load load cases.cases.
All flat roof systems must All flat roof systems must be checked to prevent pond-be checked to prevent pond-
ing problems. ing problems. See SecSee Section 4.5.tion 4.5.
5.5. SimpSimple-le-spaspan ron rollelled bed beams ams are are oftoften sen subsubstitutituted ted for for 
continuous or double-cantilevered girders where spanscontinuous or double-cantilevered girders where spans
are short. are short. The simple span The simple span beams often have beams often have adequateadequate
moment capacity. moment capacity. The connections are simple, and theThe connections are simple, and the
savings from easier erection of such systems maysavings from easier erection of such systems may
overcome the cost of any additional weight.overcome the cost of any additional weight.
6.6. For For larlarge bge bay day dimenimensiosions ins in bon both dth direirectictionsons, a p, a popuopular lar 
system consists of cold-formed or hot-rolled steelsystem consists of cold-formed or hot-rolled steel
 purlins  purlins or or joists joists spanning spanning 20 20 ft ft to to 30 30 ft ft to to secondarysecondary
trusses spanning trusses spanning to the primary trusto the primary trusses. ses. This framingThis framing
system is particularly useful when heavily loadedsystem is particularly useful when heavily loaded
monorails must be hung monorails must be hung from the structure. from the structure. The sec-The sec-
ondary trusses in conjunction with the main trussesondary trusses in conjunction with the main trusses
 provide excellent support for  provide excellent support for the monorails.the monorails.
7.7. ConConsidsideraeration tion musmust bt be ge giveiven tn to fo futuuture re expexpansansionion
and/or modification, where columns are either movedand/or modification, where columns are either moved
or eliminated. or eliminated. Such changes Such changes can generally be can generally be accom-accom-
 plished  plished with with greater greater ease ease where where simple simple span span condi-condi-
tions exist.tions exist.
88.. BBRRAACCIINNGG SSYYSSTTEEMMSS
8.8.11 RiRiggid id FrFramame e SySyststememss
There are many considerations involved in providing lateralThere are many considerations involved in providing lateral
stability to industrial structures. stability to industrial structures. If a rigid frIf a rigid frame is used, lat-ame is used, lat-
eral stability parallel to the frame is provided by the frame.eral stability parallel to the frame is provided by the frame.
However, for loads perpendicular to the main frames andHowever, for loads perpendicular to the main frames and
for wall bearing and “post and beam” construction, lateralfor wall bearing and “post and beam” construction, lateral
 bracing is  bracing is not inherent not inherent and must and must be provided. be provided. It is It is impor-impor-
tant to re-emphasizethat future expansion may dictate thetant to re-emphasize that future expansion may dictate the
use of a rigid frame or a flexible (movable) bracing scheme.use of a rigid frame or a flexible (movable) bracing scheme.
Since industrial structures are normally light and gener-Since industrial structures are normally light and gener-
ally low in profile, wind and seismic forces may be rela-ally low in profile, wind and seismic forces may be rela-
tively lowtively low. . Rigid frame Rigid frame action can action can be easily be easily and safelyand safely
achieved by providing a properly designed member at a achieved by providing a properly designed member at a col-col-
umn line. umn line. If joists are useIf joists are used as a pard as a part of the rigid frt of the rigid frame theame the
designer is cautioned on the following points:designer is cautioned on the following points:
1.1. The The desdesign ign loaloads (ds (winwind, sd, seiseismic, mic, and and concontinutinuity) ity) musmustt
 be given on the structural plans so that the joist  be given on the structural plans so that the joist manu-manu-
facturer can prfacturer can provide the proper dovide the proper design. esign. The procedureThe procedure
must be used with conscious engineering judgmentmust be used with conscious engineering judgment
and full recognition that standard steel joists areand full recognition that standard steel joists are
designed as simple span members subject to distrib-designed as simple span members subject to distrib-
uted loads. uted loads. (See the (See the Steel Joist Steel Joist Institute’s Institute’s StandardStandard
Specifications for Standard Steel Joists and Long SpanSpecifications for Standard Steel Joists and Long Span
Joists (SJI, 200Joists (SJI, 2002). 2). Bottom chords arBottom chords are normally sizede normally sized
for tension onlyfor tension only. . The simple attachment of the boThe simple attachment of the bottomttom
chord to a column to provide lateral stability willchord to a column to provide lateral stability will
cause gravity load end moments that cannot because gravity load end moments that cannot be
ignored. ignored. The designer should nThe designer should not try to select member ot try to select member 
sizes for these bottom chords since each manufac-sizes for these bottom chords since each manufac-
turer’s design is unique and proprietary.turer’s design is unique and proprietary.
2.2. It iIt is nes necescessarsary foy for thr the dee desigsigner ner to pto provrovide ide a wea well-ll-
designed connection to both the top and bottom chordsdesigned connection to both the top and bottom chords
to develop the induced moments without causingto develop the induced moments without causing
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 2121
    
excessive secondary bending moments in the joistexcessive secondary bending moments in the joist
chords.chords.
3.3. The The syssystem tem musmust hat have ave adeqdequatuate ste stiffiffnesness to s to preprevenventt
drift related problems such as cracked walls and parti-drift related problems such as cracked walls and parti-
tions, broken glass, leaking walls and roofs, and mal-tions, broken glass, leaking walls and roofs, and mal-
functioning or inoperable overhead doors.functioning or inoperable overhead doors.
88..22 BBrraacceed d SSyysstteemmss
Roof DiaphragmsRoof Diaphragms
The most economical roof bracing system is achieved byThe most economical roof bracing system is achieved by
use of a steel deck diaphragm. The deck is provided as theuse of a steel deck diaphragm. The deck is provided as the
roofing element and the effective diaphragm is obtained atroofing element and the effective diaphragm is obtained at
little additional cost (folittle additional cost (for extra der extra deck connections). ck connections). AA roof roof 
diaphragm used in conjunction with wall X-bracing or adiaphragm used in conjunction with wall X-bracing or a
wall diaphragm system is probably the most economicalwall diaphragm system is probably the most economical
 bracing system that can be achieved.  bracing system that can be achieved. Diaphragms are mostDiaphragms are most
efficient in relatively square buildings; however, an aspectefficient in relatively square buildings; however, an aspect
ratio up to three can be accommodated.ratio up to three can be accommodated.
AA cold-formed steel cold-formed steel diaphragm is analogoudiaphragm is analogous to the s to the webweb
of a plate girderof a plate girder. . That is, its main function is to resist shear That is, its main function is to resist shear 
forces. forces. The perimeter members oThe perimeter members of the diaphragm serve f the diaphragm serve asas
the “flanges.”the “flanges.”
The design procedure is quite simple. The basic parame-The design procedure is quite simple. The basic parame-
ters that control the strength and stiffness of the diaphragmters that control the strength and stiffness of the diaphragm
are:are:
11.. PPrrooffiille e sshhaappee..
2.2. DeDeck ck mamateteririal al ththicicknknesess.s.
33.. SSppaan n lleennggtthh..
4.4. The The typtype ane and spd spaciacing ong of thf the fae fastesteninning of g of the the decdeck tok to
the structural members.the structural members.
5.5. The The typtype ae and nd spaspacincing og of tf the he sidside lae lap cp connonnectectorsors..
The profile, thickness, and span of the deck are typicallyThe profile, thickness, and span of the deck are typically
 based on  based on gravity load gravity load requirements. requirements. The type The type of fasteningof fastening
(i.e., welding, screws, and power driven pins) is often (i.e., welding, screws, and power driven pins) is often basedbased
on the designer’s or contractor’s preference. Thus the mainon the designer’s or contractor’s preference. Thus the main
design variable is the spacing of the fdesign variable is the spacing of the fasteners. asteners. The designer The designer 
calculates the maximum shear per ft of diaphragm and thencalculates the maximum shear per ft of diaphragm and then
selects the fastener spacing from the load tables. Loadselects the fastener spacing from the load tables. Load
tables are most often based on the requirements set forth intables are most often based on the requirements set forth in
the Department of Army, Navy and Air Force TM 5-80-10,the Department of Army, Navy and Air Force TM 5-80-10,
Seismic Design for BuildingsSeismic Design for Buildings (Department of Army, 1992),(Department of Army, 1992),
and the Steel Deck Institute’sand the Steel Deck Institute’s  Diaphragm Design  Diaphragm Design Manual Manual 
(SDI, 1987).(SDI, 1987).
Deflections are calculated and compared with service-Deflections are calculated and compared with service-
ability requirements.ability requirements.
The calculation of flexural deformations is handled in aThe calculation of flexural deformations is handled in a
conventional manner. Shear deformations can be obtainedconventional manner. Shear deformations can be obtained
mathematically, using shear deflection equations, if themathematically, using shear deflection equations, if the
shear modulus of the formed deck material making up theshear modulus of the formed deck material making up the
diaphragm is known. Deflections can also be obtained usingdiaphragm is known. Deflections can also be obtained using
empirical equations such as those found in (Department of empirical equations such as those found in (Department of 
Army, 1992) and (SDI, 1987). In addition, most metal deck Army, 1992) and (SDI, 1987). In addition, most metal deck 
manufacturers publish tables in which strength and stiffnessmanufacturers publish tables in which strength and stiffness
(or flexibility) information is presented. In order to illus-(or flexibility) information is presented. Inorder to illus-
trate the diaphragm design procedure a design example istrate the diaphragm design procedure a design example is
 presented  presented below. The below. The calculations calculations presented presented are are based based onon
the Steel Deck Institute’s procedure (SDI, 1987)the Steel Deck Institute’s procedure (SDI, 1987)
EXAMPLE 8.2.1EXAMPLE 8.2.1
Diaphragm Design (ASD)Diaphragm Design (ASD)
Design the roof diaphragm for the structure shown in FigureDesign the roof diaphragm for the structure shown in Figure
8.2.1. 8.2.1. The eave wind The eave wind loads are shown loads are shown in the figure.in the figure.
2222 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
208'208'
96'96'
Plan Of Roof Plan Of Roof 
250 plf 250 plf 
VVVV NN
 Fig. 8.2.1  Fig. 8.2.1 ExampleExample
92'92'
Welds 36/4Welds 36/4
1 - s.l.s.1 - s.l.s.
Plan of Roof Plan of Roof 
Load DiagramLoad Diagram
Welds 36/4Welds 36/4
2 - s.l.s.2 - s.l.s.
271 plf 271 plf 
240 plf 240 plf 
 Fig. 8.2.1.1 Fig. 8.2.1.1
    
 Note that the length  Note that the length to width ratio of the to width ratio of the diaphragm doesdiaphragm does
not exceed 3, which is the generally accepted maximum for not exceed 3, which is the generally accepted maximum for 
diaphragms.diaphragms.
Assume that a 0.0358 in. thick intermediate rib deck Assume that a 0.0358 in. thick intermediate rib deck 
spanning 5 in-6 in is uspanning 5 in-6 in is used to support the gravity sed to support the gravity loads. loads. SteelSteel
 joists  joists span span in in the the north-south dinorth-south direction. rection. Use Use welds welds to to con-con-
nect the deck to the structural members and #10 screws for nect the deck to the structural members and #10 screws for 
the side laps.the side laps.
Solution:Solution:
1.1. CaCalculculatlate the the mae maximximum dum diapiaphrhragagm shem shearar..
2.2. ObtaObtain tin the she sheahear car capacpacity ity of tof the dhe deck eck frofrom thm the SDe SDII
 Diaphragm Design Manual  Diaphragm Design Manual (SDI, 1987).(SDI, 1987).
For a 20-gage (0.0358 in. thickness) deck, spanning 5For a 20-gage (0.0358 in. thickness) deck, spanning 5ft-6 in. the allowable shear is:ft-6 in. the allowable shear is:
a.a. 240 lb/f240 lb/ft with a 3t with a 36/4 we6/4 weld patteld pattern anrn and one sd one side lapide lap
screw.screw.
 b. b. 285 lb/ft 285 lb/ft with with a 36/4 a 36/4 weld pattern weld pattern and two and two sidelapsidelap
screws.screws.
c.c. 300 lb/f300 lb/ft with a 36t with a 36/5 weld /5 weld patterpattern and on and one sidene sidelaplap
screw.screw.
Use patterns a. and b. as shown in Figure 8.2.1.1:Use patterns a. and b. as shown in Figure 8.2.1.1:
3.3. CompCompute ute the the latelateral ral defdefleclection tion of of the the diadiaphrphragmagm..
For simplicity assume one sidelap screw for the entireFor simplicity assume one sidelap screw for the entire
roof.roof.
The deflection equations are:The deflection equations are:
a.a. FoFor ber bendndining:g:
 b. b. For shear:For shear:
wherewhere
ww == ththe ee eavave fe fororce ce (k(kipips/s/ftft))
 L L == ththe die diapaphrhragagm lem lengngth (th (ftft))
 D D == ththe de diaiaphphraragm gm dedeptpth (h (ftft))
GG′′ ==
From the SDI tables:From the SDI tables:
 K  K 22 == 11005566
 D D xx xx ==  D Dir ir = 909 (intermediate rib)= 909 (intermediate rib)
 K  K 11 == 00..556611
 K  K 11 == 0.0.50509 c9 cororrerespspononds ds to to 2222-g-gagage de dececk.k.
The moment of inertia,The moment of inertia,  I  I , can be based on an assumed, can be based on an assumed
area of the perimeter memberarea of the perimeter member. . Assuming the edge member Assuming the edge member 
has an area of 3.0 in.has an area of 3.0 in.22, the moment of inertia equals:, the moment of inertia equals:
 I  I = 2= 2 Ad  Ad 22 = (2)(3.0)(48= (2)(3.0)(48××12)12)22 = 1.99= 1.99××101066 in.in.44
The bending deflection equals:The bending deflection equals:
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 2323
(250)(208)(250)(208)
  = = = = 2266,,00000 0 llbb
22 22
WLWL
V V     ≅≅
26,00026,000
  = = = = 22771 1 llbb//fftt
9966 9966
V V 
vv    ≅≅
44
55
384384
bb wLwL
 EI  EI 
∆ ∆ ==
22
88
 s s
wLwL
 DG DG
∆ ∆ ==
′′
22
0.30.3
33..7788 33(( 11))(( )) xx xx
 K  K 
 D D
 K  K spanspan
 span span
    
+ + ++        
10561056
16.916.9
3.78 3.78 0.30.3(90(909)9) // 5.5 5.5 3(03(0.56.5611)5.)5.55
GG∴ ∴ = = ==′′
+ + ++
44
66
(5)(0.25)(208(5)(0.25)(208) ) ((1728)1728)
0.18 in.0.18 in.
(384)(29000)((384)(29000)(1.99x10 1.99x10 ))
bb
∆ ∆ = = ==
  
 Fig. 8.2.2  Fig. 8.2.2 Eave AngleEave Angle
 Fig. 8.2.3  Fig. 8.2.3 Shear Collector Shear Collector 
    
The shear deflection equals:The shear deflection equals:
The total deflection equals:The total deflection equals:
∆∆ == ∆∆bb ++ ∆∆ s s = 0.18 + 0.83 = 1.01 in.= 0.18 + 0.83 = 1.01 in.
To transfer the shear forces into the east and west wallsTo transfer the shear forces into the east and west walls
of the structure the deck can be welded directly to theof the structure the deck can be welded directly to the
 perimeter  perimeter beams. beams. The The deck deck must must be be connected connected to to thethe
 perimeter  perimeter beams beams with with the the same same number number of of fasteners fasteners asas
required required in the in the field of field of the the diaphragm. diaphragm. Thus,Thus, 55//88 in.in.
diaphragm arc spot welds 9 in. on center should be speci-diaphragm arc spot welds 9 in. on center should be speci-
fied at the east and west walls.fied at the east and west walls.
The reader is cautioned regarding connecting steel deck The reader is cautioned regarding connecting steel deck 
to the end walls of buildings. to the end walls of buildings. If the deck is to be If the deck is to be connectedconnected
to a shear wall and a joist is placed next to the wall,to a shear wall and a joist is placed next to the wall,
allowance must be made for the camber in the edge joist inallowance must be made for the camber in the edge joist in
order to order to connect the connect the deck to deck to the wall system. the wall system. If proper If proper 
details are not provided, diaphragm connection may not bedetails are not provided, diaphragm connection may not be
 possible, and field adjustments may be  possible, and field adjustments may be required. required. Where theWhere the
edge joist is eliminated near the endwall, the deck can oftenedge joist is eliminated near the endwall, the deck can often
 be pushed down flat on an  be pushed down flat on an endwall support. endwall support. If the joist hasIf the joist has
significant camber, it may be necessary to provide simplesignificant camber, it may be necessary to provide simple
span pieces of span pieces of deck between the wall andeck between the wall and the first joist. d the first joist. AA
heavier deck thickness may be required due to the loss inheavier deck thickness may be required due to the loss in
continuity. continuity. The edge should be The edge should be covered with a sheet metalcovered with a sheet metal
cap to protect the roofing materials. This can present ancap to protect the roofing materials. This can present an
additional problem since the sharp edge of the deck willadditional problem since the sharp edge of the deck will
stick up and possibly damage the roofing.stick up and possibly damage the roofing.
Along the north and south walls, a diaphragm chord canAlong the north and south walls, a diaphragm chord can
 be provided by attaching  be provided by attaching an angle to tan angle to the top of the he top of the joists asjoists as
shown in Figure 8.2.2. The angle also stiffens the deck edgeshown in Figure 8.2.2. The angle also stiffens thedeck edge
and prevents tearing of roofing materials along the edgeand prevents tearing of roofing materials along the edge
where no pawhere no parapet is provided rapet is provided under foot trafunder foot traffic. fic. In someIn some
designs an edge angle may also be required for the side lapdesigns an edge angle may also be required for the side lap
connections for wind forces in the east-west direction.connections for wind forces in the east-west direction.
Also, shear connectors may be required to transfer theseAlso, shear connectors may be required to transfer these
forces into the forces into the perimeter beam. perimeter beam. Shown in Figure 8Shown in Figure 8.2.3 is a.2.3 is a
typical shear collector.typical shear collector.
 Roof X-Bracing  Roof X-Bracing 
An alternative to the roof diaphragm is to use X-bracing toAn alternative to the roof diaphragm is to use X-bracing to
develop a horizontal truss system. As with the metal deck develop a horizontal truss system. As with the metal deck 
diaphragm, as the length to width ratio of the buildingdiaphragm, as the length to width ratio of the building
 becomes larger  becomes larger than 3 than 3 to to 1 t1 the diagonal he diagonal forces in forces in the the trusstruss
members may require consideration of an alternate bracingmembers may require consideration of an alternate bracing
method.method.
An especially effective way to develop an X-braced roof An especially effective way to develop an X-braced roof 
is to utilize flat bar is to utilize flat bar stock resting on the stock resting on the roof joists. roof joists. The useThe use
of ¼ in. bar stock does not usually interfere with deck of ¼ in. bar stock does not usually interfere with deck  placement and facilitates  placement and facilitates erection.erection.
Vertical Bracing Vertical Bracing 
In braced buildings the roof diaphragm loads or the roof X-In braced buildings the roof diaphragm loads or the roof X-
 bracing  bracing loads loads are are transferred transferred to to a a vertical vertical braced braced frame,frame,
which in turn transfers which in turn transfers the loads to the foundation the loads to the foundation level. level. InIn
most cases the vertical bracing is located at the perimeter of most cases the vertical bracing is located at the perimeter of 
the structure so as the structure so as not interfere with plant opernot interfere with plant operations. ations. TheThe
vertical bracing configuration most frequently used is an x-vertical bracing configuration most frequently used is an x-
 braced system  braced system using angles using angles or rods or rods designed only designed only to to func-func-
tion as tension members. However, in areas of hightion as tension members. However, in areas of high
seismicity, a vertical bracing system that incorporates ten-seismicity, a vertical bracing system that incorporates ten-
sion/compression members is often required. In sion/compression members is often required. In these cases,these cases,
other bracing forms may be used, such as, chevron bracingother bracing forms may be used, such as, chevron bracing
or eccentrically braced frames.or eccentrically braced frames.
In buildings with large aspect ratios, bracing may beIn buildings with large aspect ratios, bracing may be
required in internal bays irequired in internal bays in order to reduce the brace forces,n order to reduce the brace forces,
and to reduce foundation-overturning forces.and to reduce foundation-overturning forces.
88.3.3 TTeempmpoorraarry Bry Braacciinngg
Proper temporary bracing is essential for the timely and safeProper temporary bracing is essential for the timely and safe
erection and support of the structural framework until theerection and support of the structural framework until the
 permanent bracing system is in place.  permanent bracing system is in place. The need for tempo-The need for tempo-
rary bracing is recognized in Section M4.2 of the AISCrary bracing is recognized in Section M4.2 of the AISC
specifications (AISC, 1989), (AISC, 1999), and in Sectionspecifications (AISC, 1989), (AISC, 1999), and in Section
7.10 of the AISC7.10 of the AISC Code of Standard PracticeCode of Standard Practice (AISC, 2000).(AISC, 2000).
TheThe Code of Standard PracticeCode of Standard Practice places the  places the responsibilityresponsibility
for temporary bracing solely with the erectorfor temporary bracing solely with the erector. . This is appro-This is appro-
 priate  priate since since temporary temporary bracing bracing is is an an essential essential part part of of thethe
work of erecting the steel framework.work of erecting the steel framework.
While the general requirements of theWhile the general requirements of the Code of Standard Code of Standard 
 Practice Practice are appropriate in establishing the responsibilityare appropriate in establishing the responsibility
for temporary erection bracing, two major issues have thefor temporary erection bracing, two major issues have the
 potential to  potential to be overlooked in tbe overlooked in the process.he process.
First, it is difficult to judge the adequacy of temporaryFirst, it is difficult to judge the adequacy of temporary
 bracing  bracing in in any any particular particular situation situation using using only only the the generalgeneral
requirements as a guide. There is no “codified” standardrequirements as a guide. There is no “codified” standard
that can be applied in judging whether or not a minimumthat can be applied in judging whether or not a minimum
level of conformity has been met. However, ASCE 37-02,level of conformity has been met. However, ASCE 37-02,
 Design Loads  Design Loads on Structures During Constructionon Structures During Construction, (ASCE,, (ASCE,
2002) and AISC Design Guide 10,2002) and AISC Design Guide 10,  Erection  Erection Bracing Bracing of of 
 Low-Rise  Low-Rise Structural Structural Steel Steel FramesFrames (AISC, 1997) can be use-(AISC, 1997) can be use-
ful in making evaluations of the adequacy of proposed tem-ful in making evaluations of the adequacy of proposed tem-
 porary  porary bracing bracing and and in in establishing establishing the the need need for for suchsuch
 bracing. bracing.
Secondly, theSecondly, the Code of Standard PracticeCode of Standard Practice does notdoes not
emphasize that the process of erection can induce forcesemphasize that the process of erection can induce forces
and stresses into components and systems such as footingsand stresses into components and systems such as footings
and piers that are not part of the structural steel framework.and piers that are not part of the structural steel framework.
Unless otherwise specified in the contract documents, it isUnless otherwise specified in the contract documents, it is
the practice of architects and engineers to design the ele-the practice of architects and engineers to design the ele-
ments and systems in a building for the forces acting uponments and systems in a building for the forces acting upon
the completed structure only. An exception to this is thethe completed structure only. An exception to this is the
requirement in OSHA, Subpart R (OSHA, 2001) that col-requirement in OSHA, Subpart R (OSHA, 2001) that col-
2424 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
22(0.25)(208)(0.25)(208)
0.83 in.0.83 in.
(8)(96)(16.9)(8)(96)(16.9)
 s s∆ ∆ = = ==
    
umn bases be designed to resist a 300-lb downward loadumn bases be designed to resist a 300-lb downward load
acting at 18 in. from the faces of columns.acting at 18 in. from the faces of columns.
Without a detailed erection bracing plan it is difficult for Without a detailed erection bracing plan it is difficult for 
anyone in the design/construction process to evaluate theanyone in the design/construction process to evaluate the
 performance  performanceof of the the erector erector relative relative to to bracing bracing withoutwithout
 becoming involved in the process itself.  becoming involved in the process itself. This is inconsistentThis is inconsistent
with maintaining the determination of temporary bracing aswith maintaining the determination of temporary bracing as
the sole responsibility of the erector. The lack of emphasisthe sole responsibility of the erector. The lack of emphasison the necessity that the erector must check the effect of on the necessity that the erector must check the effect of 
erection induced forces on other elements has at timeserection induced forces on other elements has at times
allowed erection problems to be erroneously interpreted asallowed erection problems to be erroneously interpreted as
having been caused by other reasons. This is most obvioushaving been caused by other reasons. This is most obvious
in the erection of steel columns.in the erection of steel columns.
To begin and pursue the erection of a steel framework itTo begin and pursue the erection of a steel framework it
is necessary to eris necessary to erect columns first. ect columns first. This means that at oneThis means that at one
time or another each building column is time or another each building column is set in place withoutset in place without
stabilizing framing attached to it in two perpendicular stabilizing framing attached to it in two perpendicular 
directions. directions. Without sucWithout such framing the h framing the columns must cacolumns must can-n-
tilever for a time from the supporting footing or pier unlesstilever for a time from the supporting footing or pier unless
adequate guys brace them or unless the coladequate guys brace them or unless the columns and beamsumns and beams
are designed and constructed as rigid frames in both direc-are designed and constructed as rigid frames in both direc-
tions. tions. The forces induced by the caThe forces induced by the cantilevered column on thentilevered column on the
 pier or footing  pier or footing may not have may not have been considered by tbeen considered by the build-he build-
ing designer unless this ing designer unless this had been specifically rehad been specifically requested. quested. ItIt
is incumbent upon the steel erector to make a determinationis incumbent upon the steel erector to make a determination
of the adequacy of the foundation to support cantileveredof the adequacy of the foundation to support cantilevered
columns during erection.columns during erection.
Trial calculations suggest that large forces can beTrial calculations suggest that large forces can be
induced into anchor rods, piers and footings by relativelyinduced into anchor rods, piers and footings by relatively
small forces acting asmall forces acting at or near the t or near the tops of columns. tops of columns. AlsoAlso
wind forces can easily be significant, as can be seen in thewind forces can easily be significant, as can be seen in the
following example. Figure 8.3.1 shows a section of following example. Figure 8.3.1 shows a section of 
unbraced frame consisting of three columns and two unbraced frame consisting of three columns and two beams.beams.
The beams are takeThe beams are taken as pin ended. n as pin ended. Wind forcWind forces are actinges are acting
 perpendicular to the frame  perpendicular to the frame line.line.
Using a shape factor of 2.0 for a 40 mUsing a shape factor of 2.0 for a 40 mph wind directed atph wind directed at
the webs of thethe webs of the WW12 columns, a base moment of approxi-12 columns, a base moment of approxi-
mately 18,000 ft-lbs occurs. If a 5 in. by 5 in. placementmately 18,000 ft-lbs occurs. If a 5 in. by 5 in. placement
 pattern were  pattern were used wused with ith four anchor four anchor rods and rods and an an ungroutedungrouted
 base plate, a  base plate, a tension force tension force of approximately of approximately 21.6 kips would21.6 kips would
 be applied  be applied to the to the two two anchor rods. The anchor rods. The allowable force allowable force for for 
a ¾ in. Grade 36 anchor a ¾ in. Grade 36 anchor rod is 8.4 kips. rod is 8.4 kips. Even if the boltsEven if the bolts
were fully in the concrete, they would be severely over-were fully in the concrete, they would be severely over-
stressed and would likely fail. Four 1stressed and would likely fail. Four 111//88 in. anchor rodsin. anchor rods
would be required would be required to resist the wind foto resist the wind force. rce. Of course notOf course not
only the size of the anchor rod is affected, but the design of only the size of the anchor rod is affected, but the design of 
the base plate and its attachment to the column, the spacingthe base plate and its attachment to the column, the spacing
of the anchor rods and the design of the pier and footingof the anchor rods and the design of the pier and footing
must also be checked.must also be checked.Guying can also induce forces into the structure in theGuying can also induce forces into the structure in the
form of base shears aform of base shears and uplift forces. nd uplift forces. These forces may notThese forces may not
have been provided for in the sizing of the affected mem-have been provided for in the sizing of the affected mem-
 bers.  bers. The The erector erector must must also also check check this. this. The The placement placement of of 
material such as decking on the incomplete structure canmaterial such as decking on the incomplete structure can
induce unanticipated induce unanticipated loadings. loadings. This loading This loading must also bemust also be
considered explicitly. OSHA, Subpart R states that no deck-considered explicitly. OSHA, Subpart R states that no deck-
ing bundles may be placed on the frame until a qualifieding bundles may be placed on the frame until a qualified
 person has  person has documented that documented that a a structure or structure or portion portion is is capa-capa-
 ble of supporting  ble of supporting the load.the load.
Erection bracing involves Erection bracing involves other issues as other issues as well. well. First, theFirst, the
Code of Standard PracticeCode of Standard Practice distinguishes between frames indistinguishes between frames in
which the frame is stabilized by construction in the controlwhich the frame is stabilized by construction in the control
of the Erector versus those frames in of the Erector versus those frames in which other non-struc-which other non-struc-
tural steel elements are required for the stability of thetural steel elements are required for the stability of the
frame. The distinction is drawn because the timing of theframe. The distinction is drawn because the timing of the
removal of bracing is removal of bracing is affected. affected. In a structural steel In a structural steel frame,frame,
where lateral stability is achieved in the design and detail-where lateral stability is achieved in the design and detail-
ing of the framework itself, the bracing can be removeding of the framework itself, the bracing can be removed
when the erector’s work is complete. when the erector’s work is complete. AA steel framework thatsteel framework that
relies on elements other than the structural steel to providerelies on elements other than the structural steel to provide
lateral stability should have the necessary elements provid-lateral stability should have the necessary elements provid-
ing the stability identified in the contract documents alonging the stability identified in the contract documents along
with the schedule of with the schedule of their completion. their completion. The coordination of The coordination of 
the installation of such elements is a matter that must bethe installation of such elements is a matter that must be
addressed by the General Contractor.addressed by the General Contractor.
Temporary support beyond the requirements discussedTemporary support beyondthe requirements discussed
above would be the responsibility of the owner according toabove would be the responsibility of the owner according to
thethe Code of Standard PracticeCode of Standard Practice. For example, if the steel. For example, if the steel
frame and its temporary bracing are to support other non-frame and its temporary bracing are to support other non-
structural elements, the responsibility for this must bestructural elements, the responsibility for this must be
clearly identified and the reactions from the elements are toclearly identified and the reactions from the elements are to
 be provided  be provided to the to the erector. Otherwise the erector. Otherwise the responsibility for responsibility for 
this falls to others, not the erector.this falls to others, not the erector.
The timing of column base grouting affects the perform-The timing of column base grouting affects the perform-
ance of column bases during erection. Theance of column bases during erection. The Code of Stan-Code of Stan-
dard Practicedard Practice establishes the timing of grouting and establishes the timing of grouting and assignsassigns
the responsibility for grouting to the owner. The erector the responsibility for grouting to the owner. The erector 
should be aware of the schedule for this work.should be aware of the schedule for this work.
All of the foregoing points to the need for care, attentionAll of the foregoing points to the need for care, attention
and thoroughness on the part of tand thoroughness on the part of the erector in preparing andhe erector in preparing and
following a temporary bracing and erection scheme.following a temporary bracing and erection scheme.
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 2525
4400'' 4400''
WW2244 WW2244
WW1122 2244''
 Fig.  Fig. 8.3.1 8.3.1 Erection Bracing ExampleErection Bracing Example
    
99.. CCOOLLUUMMN N AANNCCHHOORRAAGGEE
Building columns must be anchored to the foundation sys-Building columns must be anchored to the foundation sys-
tem to transfer tension forces, shear forces, and overturningtem to transfer tension forces, shear forces, and overturning
moments. This discussion will be limited to the design of moments. This discussion will be limited to the design of 
column anchorages for shear and tension forces. The prin-column anchorages for shear and tension forces. The prin-
ciples discussed here can be applied to the design of anchor-ciples discussed here can be applied to the design of anchor-
ages for overturning moments.ages for overturning moments.
Tension forces are typically transferred to the Tension forces are typically transferred to the foundationfoundation
system with anchor rods. system with anchor rods. Shear forces can be traShear forces can be transferred tonsferred tothe foundation system through bearing, friction, or shear the foundation system through bearing, friction, or shear 
friction. The principal means of shear transfer considered infriction. The principal means of shear transfer considered in
this section is through bearing of the anchor rods andthis section is through bearing of the anchor rods and
through bearing of embedded components of the column.through bearing of embedded components of the column.
Friction should not be considered if seismic conditionsFriction should not be considered if seismic conditions
exist. Design for these various anchorage methods isexist. Design for these various anchorage methods is
addressed in the following text.addressed in the following text.
Improper design, detailing and installation of anchor rodsImproper design, detailing and installation of anchor rods
have caused numerous structural problems in industrialhave caused numerous structural problems in industrial
 buildings.  buildings. These problems include:These problems include:
1.1. InInadadeqequauate ste sizizining of g of ththe ane anchchor ror rodods,s,
2.2. InaInadeqdequatuate dee develvelopmopment ent of tof the ahe anchnchor ror rods ods for for tenten--
sion,sion,
3.3. InaInadeqdequatuate dee desigsign or n or detdetailailing ing of tof the fhe founoundatdation ion for for 
forces from the anchor rods,forces from the anchor rods,
4.4. InInadadeqequauate te babase se plaplate te ththicicknknesess,s,
5.5. InaInadeqdequatuate dee desigsign ann and/or d/or detadetailiniling of g of the athe anchnchor ror rod -od -
 base plate interface, base plate interface,
6.6. MisMisaligalignmenment ont or mir misplsplaceacemenment of t of the the ancanchor hor rodrods dus dur-r-
ing installation, anding installation, and
77.. FFaattiigguuee..
The readeThe reader should be familr should be familiar with the OSHAiar with the OSHA requirrequire-e-
ments contained inments contained in Safety and Health Standards for theSafety and Health Standards for the
Construction IndustryConstruction Industry, 29 CFR 1926, 29 CFR 1926  Part  Part R R Safety Safety Stan-Stan-
dards for Steel Erectiondards for Steel Erection, (OSHA, 2001). This document, (OSHA, 2001). This document
was partially produced to prevent construction accidentswas partially produced to prevent construction accidents
associated with column base plates. For example, OSHAassociated with column base plates. For example, OSHA
requires that all column based have four anchor rods.requires that all column based have four anchor rods.
The following discussion presents methods of designingThe following discussion presents methods of designing
and detailing column bases.and detailing column bases.
9.19.1 ReResisiststining Tg Tenensision Fon Fororceces wis with th AnAnchchoror RoRodsds
The design of anchor rods for tension consists The design of anchor rods for tension consists of four steps:of four steps:
1.1. DeteDeterminrmine te the he maxmaximuimum nem net ut uplifplift fot for tr the he colcolumnumn..
2.2. SelSelect ect the the ancanchor hor rod rod matmaterierial aal and nnd numbumber er and and sizsize of e of 
anchor rods to accommodate this upliftanchor rods to accommodate this uplift
3.3. DeteDeterminrmine the the ape appropropripriate ate basbase ple plate ate sizsize, the, thickicknesnesss
and welding to transfer the uplift forces. Refer toand welding to transfer the uplift forces. Refer to
AISC Design Guide 1 (AISC, 1990).AISC Design Guide 1 (AISC, 1990).
4.4. DeteDeterminrmine the the mee methothod fod for dr deveevelopiloping tng the ahe anchnchor or rodrod
in the concrete (i.e. transferring the tin the concrete (i.e. transferring the tension force fromension force from
the anchor rod to the concrete foundation).the anchor rod to the concrete foundation).
Step 1Step 1
The maximum net uplift for the column The maximum net uplift for the column is obtained from theis obtained from the
structural analysis of the building for the prescribed build-structural analysis of the building for the prescribed build-
ing loads. The use of light metal roofs on industrial build-ing loads. The use of light metal roofs on industrial build-
ings is very popular. As a result of this, the uplift due toings is very popular. As a result of this, the uplift due to
wind often exceeds the dead load; thus the supportingwind often exceeds the dead load; thus the supporting
columns are subjected to net uplift forces. In addition,columns are subjected to net uplift forces. In addition,
columns in rigid bents or braced bays may be subjected tocolumns in rigid bents or braced bays may be subjected to
net uplift forces due to overturning.net uplift forces due to overturning.
Step 2Step 2
Anchor rods should be specified to conform to ASTMAnchor rods should be specified to conform to ASTM
F1554. Grades 36, 55 and 105 are available in this specifi-F1554. Grades 36, 55 and 105 are available in this specifi-
cation where the grade number represents the yield stress of cation where the grade number represents the yieldstress of 
the anchor. Unless otherwise specified, the end of anchor the anchor. Unless otherwise specified, the end of anchor 
will be color coded to identify its grade. Welding is permit-will be color coded to identify its grade. Welding is permit-
ted to the Grade 36 and also to the Grade 55 if it conformsted to the Grade 36 and also to the Grade 55 if it conforms
to the S1 supplement.to the S1 supplement.
Anchor rods should no longer be specified to A307 evenAnchor rods should no longer be specified to A307 even
if the intent is to use the A307 Grade C anchor that con-if the intent is to use the A307 Grade C anchor that con-
forms to A36 properties. Anchor rods conforming to theforms to A36 properties. Anchor rods conforming to the
ASTM specifications listing of Anchor Rods and ThreadedASTM specifications listing of Anchor Rods and Threaded
Bolts in the 1999 AISCBolts in the 1999 AISC LRFD Specifica LRFD Specificationtion can be used ascan be used as
well as 304 and 316 stainless steels.well as 304 and 316 stainless steels.
The number of anchor rods required is a function of theThe number of anchor rods required is a function of the
maximum net uplift on the column and the allowable tensilemaximum net uplift on the column and the allowable tensile
load per rod for the anchor rod material chosen. Pryingload per rod for the anchor rod material chosen. Prying
forces in anchor rods are typically neglected. This is usuallyforces in anchor rods are typically neglected. This is usually
 justified when the  justified when the base plate thickness is calculated base plate thickness is calculated assum-assum-ing cantilever bending about the web and/or flange of theing cantilever bending about the web and/or flange of the
2626 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
Table 9.1.1 Table 9.1.1 Allowable BoAllowable Bolt Fatigue Strelt Fatigue Stressss
Number ofNumber of
Loading CyclesLoading Cycles
aa
  
Allowable TensileAllowable Tensile
Stress (psi)Stress (psi)
20,000 to 100,00020,000 to 100,000
100,000 to 500,000100,000 to 500,000
500,000 to 2,000,000500,000 to 2,000,000
Over 2,000,000Over 2,000,000
40,00040,000
25,00025,000
15,00015,000
10,00010,000
aa
 – – These categories correspond to the loadingThese categories correspond to the loading
conditions indicated in Appendix K of conditions indicated in Appendix K of the AISCthe AISC
Specification.Specification.  
    
column section (as described in Step 3 below). However,column section (as described in Step 3 below). However,
calculations have shown that prying forces may calculations have shown that prying forces may not be neg-not be neg-
ligible when the rods are positioned ligible when the rods are positioned outside the column pro-outside the column pro-
file and the file and the rod forces rod forces are large. are large. AA conservative estimate fconservative estimate for or 
these prying forces can be obtained using a method similar these prying forces can be obtained using a method similar 
to that described for hanger connections in the AISCto that described for hanger connections in the AISC  Man- Man-
ual of Steel Constructionual of Steel Construction..
Another consideration in selection and sizing of anchor Another consideration in selection and sizing of anchor rods is fatigue. rods is fatigue. For most building applications, where For most building applications, where upliftuplift
loads are generated from wind and seismic forces, fatigueloads are generated from wind and seismic forces, fatigue
can be neglected because the maximum design wind andcan be neglected because the maximum design wind and
seismic loads occur infrequentlyseismic loads occur infrequently. . However, for aHowever, for anchor rodsnchor rods
used to anchor machinery or equipment where the fullused to anchor machinery or equipment where the full
design loads may occur more often, fatigue should be con-design loads may occur more often, fatigue should be con-
sidered. sidered. In addition, in In addition, in buildings where buildings where crane load crane load cyclescycles
are significant, are significant, fatigue should fatigue should also be also be considered. considered. AISEAISE
Technical Report No. 13 for the design of steel mill build-Technical Report No. 13 for the design of steel mill build-
ings recommends that 50 percent of the maximings recommends that 50 percent of the maximum crane lat-um crane lat-
eral loads or side thrust be used for fatigue considerations.eral loads or side thrust be used for fatigue considerations.
In the past, attempts have been made tIn the past, attempts have been made to pretension or pre-o pretension or pre-
load anchor rods in the concrete to prevent fluctuation of load anchor rods in the concrete to prevent fluctuation of 
the tensile stress in anchor rods and, therefore, eliminatethe tensile stress in anchor rods and, therefore, eliminate
fatigue confatigue concerns. cerns. This is This is not recommended, not recommended, unless theunless the
anchor rods are re-tensioned to accommodate creep in theanchor rods are re-tensioned to accommodate creep in the
supporting concrete foundation. If setting nuts aresupporting concrete foundation. If setting nuts are
employed below the base plate, pretensioning can beemployed below the base plate, pretensioning can be
employed to provide a tight connection between the baseemployed to provide a tight connection between the base
 plate and the  plate and the anchors.anchors.
Table 9.1.1 shows recommended allowable fatigueTable 9.1.1 shows recommended allowable fatigue
stresses for stresses for non-pretensioned steel bolts. non-pretensioned steel bolts. These values areThese values are
 based on  based on S-N (stress S-N (stress verse number verse number of cycles) of cycles) data for data for a vari-a vari-
ety of difety of different types oferent types of bolts. f bolts. (These data wer(These data were obtainede obtained
from correspondence with Professor W. H. Munse of thefrom correspondence with Professor W. H. Munse of the
University of Illinois and are based on results from a num-University of Illinois and are based on results from a num-
 ber  ber of of test test studies.) studies.) By By examining examining these these values, values, it it can can bebe
ascertained that, for the AISE loading condition fatigue wiascertained that, for the AISE loading condition fatigue willll
not govern when ASTM 1554 Grade 36 anchor rods arenot govern when ASTM 1554 Grade 36 anchor rods are
used. However, fatigue can govern the design of higher used. However, fatigue can govern the design of higher 
strength anchor rods for this load case.strength anchor rods for this load case.
Step 3Step 3
Base plate thickness may be governed by bending associ-Base plate thickness may be governed by bending associ-
ated with compressive ated with compressive loads or tensile loads or tensile loads. loads. For compres-For compres-
sive loads, the design procedure illustrated in the “Columnsive loads, the design procedure illustrated in the “Column
Base Plates” section of Part 3 of Base Plates” section of Part 3 of the AISC 9th Editionthe AISC 9th Edition Man- Man-
ual of Steel Constructionual of Steel Construction, and Part 14 of the Third Edition, and Part 14 of the Third Edition
of theof the  LRFD  LRFD Manual Manual of of Steel Steel ConstructionConstruction, may be fol-, may be fol-
lowed. lowed. However, However, for lightly loaded for lightly loaded base plates base plates where thewhere the
dimensions “m” and “n” (as defined in this procedure) aredimensions “m” and “n” (as defined in this procedure) are
small, thinner base plate thickness can be obtained usingsmall, thinner base plate thickness can be obtained using
yield line theory.yield line theory.
For tensile loads, a simple approach is to assume theFor tensile loads, asimple approach is to assume the
anchor rod loads generate bending moments in the baseanchor rod loads generate bending moments in the base
 plate  plate consistent consistent with with cantilever cantilever action action about about the the web web or or 
flanges of flanges of the column the column section (one-way section (one-way bending). bending). If theIf the
web is taking the anchor load from the base plate, the webweb is taking the anchor load from the base plate, the web
and its attachment to the and its attachment to the base plate should bbase plate should be checked. e checked. AA
more refined analysis for anchor rods positioned inside themore refined analysis for anchor rods positioned inside the
column flanges would consider bending about both the webcolumn flanges would consider bending about both the web
and the column and the column flanges (two-way flanges (two-way bending). bending). For the two-For the two-
way bending approach, the derived bending momentsway bending approach, the derived bending momentsshould be consistent with compatibility requirements for should be consistent with compatibility requirements for 
deformations in the basdeformations in the base plate. e plate. In either case, In either case, the effectivethe effective
 bending  bending width width for for the the base base plate plate can can be be conservativelyconservatively
approximated using a 45° distribution from the approximated using a 45° distribution from the centerline of centerline of 
the anchor rod to the the anchor rod to the face of the column fface of the column flange or web. lange or web. Cal-Cal-
culations for required base plate thickness for uplift (ten-culations for required base plate thickness for uplift (ten-
sile) loads are illustrated in Examples 9.4.1 and 9.4.2.sile) loads are illustrated in Examples 9.4.1 and 9.4.2.
Step 4Step 4
Appendix D of ACI 318-02 (ACI Appendix D of ACI 318-02 (ACI 2002) and Appendix B of 2002) and Appendix B of 
ACI 349-01 (ACI 2001) both address the anchoring to con-ACI 349-01 (ACI 2001) both address the anchoring to con-
crete of cast-in or post-installed expansion or undercutcrete of cast-in or post-installed expansion or undercut
anchors. These appendices do not cover adhesive anchorsanchors. These appendices do not cover adhesive anchors
and grouted anchors. and grouted anchors. The provisions in both appendices areThe provisions in both appendices are
 based  based on on the the Concrete Concrete Capacity Capacity Design Design (CCD) (CCD) Method.Method.
The current ACI 349-01 Appendix B provisions represent aThe current ACI 349-01 Appendix B provisions represent a
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 2727
hh
ef ef 
TT
11
1.51.5
uu
f =f =ttf f tt Tensile stressTensile stress
in concrete alongin concrete along
surface of stress cone.surface of stress cone.
 A A AA
3h3h
ef ef 
3h3h
ef ef 
View A - AView A - A
 Fig. 9.1.1  Fig. 9.1.1 Full Breakout Cone in TFull Breakout Cone in Tension per ACI 318-02ension per ACI 318-02
    
significant change to the previous (ACI 349-97) criteria for significant change to the previous (ACI 349-97) criteria for 
anchoring.anchoring.
In the CCD method tIn the CCD method the concrete cone is considered to behe concrete cone is considered to be
formed at an angle of approximately 34 degrees (1 to 1.5formed at an angle of approximately 34 degrees (1 to 1.5
slope) rather slope) rather than the previously than the previously assumed 45. assumed 45. For simplifi-For simplifi-
cation of application, the cone is considered to be squarecation of application, the cone is considered to be square
rather than rorather than round in plan. und in plan. See Figure 9.1.1.See Figure 9.1.1.
The concrete breakout stress (The concrete breakout stress ( f  f t t  in Figure 9.1.1) in thein Figure 9.1.1) in theCCD method is considered to decrease with increase in sizeCCD method is considered to decrease with increase in size
of the breakout surface. Consequently, the increase inof the breakout surface. Consequently, the increase in
strength of the breakout in the CCD method is proportionalstrength of the breakout in the CCD method is proportional
to the embedment depth to the power of 1.5 (or to the power to the embedment depth to the power of 1.5 (or to the power 
ofof 55//33 for deeper embedments). With a constant breakoutfor deeper embedments). With a constant breakout
stress on the failure surface, as was considered in ACI 349-stress on the failure surface, as was considered in ACI 349-
97, the breakout strength is proportional to 97, the breakout strength is proportional to the square of thethe square of the
embedment depth.embedment depth.
Appendix D of ACI 318-02 permits non-ductile designAppendix D of ACI 318-02 permits non-ductile design
except for anchor rods used in regions of moderate or highexcept for anchor rods used in regions of moderate or high
seismic risk. seismic risk. In AppeIn Appendix B of ndix B of ACI 349-01 three alterna-ACI 349-01 three alterna-
tive embedment design methodologies are provided:tive embedment design methodologies are provided:
1.1. The The desdesign ign conconcrecrete bte breareakoukout tet tensinsile sle stretrengtngth, sh, sideide
 blowout  blowout strength, strength, or or pullout pullout strength, strength, of of the the anchor anchor 
and 65 percent of the concrete breakout shear strengthand 65 percent of the concrete breakout shear strength
must exceed the ultimate strength of the embedmentmust exceed the ultimate strength of the embedment
steel.steel.
2.2. The The desdesign ign strstrengength oth of thf the coe concrncrete ete musmust ext exceeceed thd thee
yield strength of the anchor by 33 percent.yield strength of the anchor by 33 percent.
3.3. NonNon-du-ductictile ale anchnchor dor desiesign ign is pes permitrmitted ted proprovidevided thad thatt
the design strength of the concrete is lthe design strength of the concrete is limited to 60 per-imited to 60 per-
cent of the design strength.cent of the design strength.
AISC in Section J10. (AISC, 1999) defers anchor designAISC in Section J10. (AISC, 1999) defers anchor design
to ACI 318. Section 15.8.3.3 of ACI 318-02 requires thatto ACI 318. Section 15.8.3.3 of ACI 318-02 requires that
anchor rods and mechanical connections reach their designanchor rods and mechanical connections reach their design
strength before anchorage failure or failure of the strength before anchorage failure or failure of the surround-surround-
ing concrete. ing concrete. It is suggested It is suggested in this design in this design guide that theguide that the
design generally follow the second and third approachesdesign generally follow the second and third approaches
given above. For strength design, it is presumed that ASCE-7given above. For strength design, it is presumed that ASCE-7
load factors are employed. Thus, theload factors are employed. Thus, the φφ factors used in thisfactors used in this
document will didocument will differ from those used in Appendix D of ACIffer from those used in Appendix D of ACI
349-01. 349-01. ACI 349-01 uses ACI 349-01 uses load factors of load factors of 1.4D and 1.7L,1.4D and 1.7L,
and f factors that conform in general to those in Appendixand f factors that conform in general to those in Appendix
C of C of ACI 318-02. ACI 318-02. TheThe φφ factors used herein correspond tofactors used herein correspond to
those in D4.4 of Appendix D and 9.3 of ACI 318-02.those in D4.4 of Appendix D and 9.3 of ACI 318-02.
If an anchor is designed to lap with reinforcement, theIf an anchor is designed to lap with reinforcement, the
anchor capacity can be taken asanchor capacity can be taken as φφ A A se se F  F  y y as the lap spliceas the lap splice
length will ensure that ductillength will ensure that ductile behavior will occur.e behavior will occur.  AA se se is theis the
effective cross-sectional area that is the tensile stress areaeffective cross-sectional area that is the tensile stress area
for threaded rods.for threaded rods. φφ equals 0.9 as prescribed in Chapter 9equals 0.9 as prescribed in Chapter 9
of of ACI 318-02. ACI 318-02. If the anchor is If the anchor is resisted solely by concrete,resisted solely by concrete,
one needs to have the concrete designed with additionalone needs to have the concrete designed with additional
capacity in order to insure capacity in order to insure ductility in the connection. ductility in the connection. ACIACI
318 in Section 15.8.3.3 does not define what is meant by318 in Section 15.8.3.3 does not define what is meant by
achieving anchor rod (and mechanical connection) designachieving anchor rod (and mechanical connection) design
strength before ancstrength before anchorage or conchorage or concrete failure. rete failure. In order toIn order to
achieve this, it is proposed to have the concrete reach aachieve this, it is proposed to have the concrete reach a
capacity of 1.25 (capacity of 1.25 (φφ A A se se F  F  y y). ). This is baThis is based on sed on the requirementthe requirement
in ACI 318 Section 12.14.3.2 that a full mechanical splicein ACI 318 Section 12.14.3.2 that a full mechanical splice
shall develop 1.25shall develop 1.25 F  F  y y. . Alternately, the Alternately, the author suggests lim-author suggests lim-iting the non-ductile anchorage capacity to iting the non-ductile anchorage capacity to 70 percent of the70 percent of the
typical design strength, which is somewhat less restrictivetypical design strength, which is somewhat less restrictive
than the 60 percent reduction used in Appendix B of ACIthan the 60 percent reduction used in Appendix B of ACI
349-01.349-01.
Hooked anchor rods usually fail by straightening andHooked anchor rods usually fail by straightening and
 pulling out of the concrete.  pulling out of the concrete. This failure is precipitated by aThis failure is precipitated by a
localized bearing failure in the concrete above the hook.localized bearing failure in the concrete above the hook.
Calculation of the development load provided by a hook isCalculation of the development load provided by a hook is
illustrated in Example 9.4.1. illustrated in Example 9.4.1. As indicated in Example 9.4.1,As indicated in Example 9.4.1,
a hook is generally not capable of developing the recom-a hook is generally not capable of developing the recom-
mended tensile capacity mentioned in the previous para-mended tensile capacity mentioned in the previous para-
graph. graph. Therefore, hooks shoTherefore, hooks should only be used when uld only be used when tensiontension
in the anchor rod is small.in the anchor rod is small.
Appendix D of ACI 318-02 has a pullout capacity for aAppendix D of ACI 318-02 has a pullout capacity for a
hooked anchor ofhooked anchor of φψ φψ 44(0.9(0.9  f  f ′′cceehhd d oo) which is based on an) which is based on an
anchor with diameteranchor with diameter d d oo bearing against the hook extension bearing against the hook extension
ofof eehh.. φφ is taken as 0.70. The hook extension is limited to ais taken as 0.70. The hook extension is limited to a
maximum of 4.5maximum of 4.5d d oo.. ψ ψ 44 equals 1.0 if the anchor is locatedequals 1.0 if the anchor is located
2828 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
TTuu
aa
hh
ef ef 
hh
xx
x = a - x = a - 3(h-h 3(h-h ))ef ef 
bb
y = b - y = b - 3(h-h 3(h-h ))
yy
hh
uuTT
hh
ef ef 
uuTT
ef ef 
uuTT
 Fig. 9.1.2  Fig. 9.1.2 Breakout Cone for Group Breakout Cone for Group Anchors in Thin SlabAnchors in Thin Slab
    
where the concrete is cracked at service load, orwhere the concrete is cracked at service load, or ψ ψ 44 equalsequals
1.4 if it is not cracked.1.4 if it is not cracked.
Tests have shown that a heavy bolt head, or a heavy hexTests have shown that a heavy bolt head, or a heavy hex
nut on a threaded rod, will develop the full tensile capacitynut on a threaded rod, will develop the full tensile capacity
of normal strength anchor rods when properly embeddedof normal strength anchor rods when properly embedded
and confined in concrete. With high strength anchor rods,and confined in concrete. With high strength anchor rods,
washer plates may be necessary to obtain the full capacitywasher plates may be necessary to obtain the full capacity
of the anchors. Therefore, the design for development for of the anchors. Therefore, the design for development for headed anchor rods (typically threaded rods with headed anchor rods (typically threaded rods with heavy hexheavy hex
nuts) is a matter of determining the required embedmentnuts) is a matter of determining the required embedment
depths, edge distances and/or steel reinforcement to preventdepths, edge distances and/or steel reinforcement to prevent
concrete breakout failure prior to the development of theconcrete breakout failure prior to the development of the
recommended tensile capacity for the rod.recommended tensile capacity for the rod.
As presented in Appendix B of ACI 349-01, failureAs presented in Appendix B of ACI 349-01, failure
occurs in the concrete when tensile stresses along the sur-occurs in the concrete when tensile stresses along the sur-
face of a stress cone surrounding the anchor rod exceed theface of a stress cone surrounding the anchor rod exceed the
tensile strength of the concrete. The extent of this stresstensile strength of the concrete. The extent of this stress
cone is a function of the embedment depth, the thickness of cone is a function of the embedment depth, the thickness of 
the concrete, the spacing between adjacent anchors and thethe concrete, the spacing between adjacent anchors and the
location of adjacent free edges in the concrete. The shapeslocation of adjacent free edges in the concrete. The shapes
of these stress cones for a variety of situations are illustratedof these stress cones for a variety of situations are illustrated
in Figures 9.1.1, 9.1.2 and 9.1.3.in Figures 9.1.1, 9.1.2 and 9.1.3.
The stress cone checks rely upon the strength of plainThe stress cone checks rely upon the strength of plain
concrete for developing the anchor rods and typically applyconcrete for developing the anchor rods and typically apply
when columns are supported directly on spread footings,when columns are supported directly on spread footings,
concrete mats or concrete mats or pile caps. pile caps. However, in However, in some instances thesome instances the
 projected  projected area area of of the the stress stress cones cones or or overlapping overlapping stressstress
cones is extremely cones is extremely limited due to edge conlimited due to edge constraints. straints. Conse-Conse-quently the tensile strength of the anchor rods cannot bequently the tensile strength of the anchor rods cannot be
fully developed with plain concrete. This is often the casefully developed with plain concrete. This is often the case
with concrete piers. with concrete piers. In these instancesIn these instances, steel reinforcement, steel reinforcement
in the concrete is used to carry the force from the anchor in the concrete is used to carry the force from the anchor 
rods. This reinforcement often doubles as the reinforcementrods. This reinforcement often doubles as the reinforcement
required to accommodate the tension and/or bending forcesrequired to accommodate the tension and/or bending forces
in the pier. The reinforcement must be sized and developedin the pier. The reinforcement must be sized and developed
for the required tensile capacity of the anchor rods on bothfor the required tensile capacity of the anchor rods on both
sides of the potential failure plane described in Figure 9.1.4.sides of the potential failure plane described in Figure 9.1.4.
The anchor rod embedmentlengths are determined fromThe anchor rod embedment lengths are determined from
the required development lengths for this reinforcing steel.the required development lengths for this reinforcing steel.
Hooks or bends can be added to this reinforcement to min-Hooks or bends can be added to this reinforcement to min-
imize development length in the breakout cone.imize development length in the breakout cone.
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 2929
 Fig. 9.1.3  Fig. 9.1.3 Breakout Cone in TBreakout Cone in Tension Near an Edgeension Near an Edge
hh
ef ef 
TTuu
 A A AA
1.5h1.5hef ef 
1.5h1.5h
ef ef 
View A - AView A - A
1.51.5
11
cc
1.5h1.5h
ef ef 
11
cc
11
Edge of Edge of 
ConcreteConcrete
hh
ef ef 
 Anchor  Anchor 
RodRod
Hooked Bar Hooked Bar 
If RequiredIf Required Top Of Top Of 
ConcreteConcrete
PotentialPotential
Failure PlaneFailure Plane
Reinforcing steel to beReinforcing steel to be
sized and developedsized and developed
for the recommendedfor the recommended
tensile capacity of thetensile capacity of the
anchor rods on bothanchor rods on both
sides of the potentialsides of the potential
failure plane.failure plane.
TT
11
1.51.5
gg
uu
   1   1
   1   1
   /   /   2   2
   "   "
 Fig. 9.1.4  Fig. 9.1.4 The Use of Steel Reinforcement for Developing Anchor RodsThe Use of Steel Reinforcement for Developing Anchor Rods
NNsbsb
cc
11
HH
H = LateralH = Lateral
Bursting ForceBursting Force
f f tt
f f tt
 Fig. 9.1.5  Fig. 9.1.5 Lateral Bursting Forces for Anchor RodsLateral Bursting Forces for Anchor Rods
in Tension Near an Edgein Tension Near an Edge
    
Appendix D of ACI 318-02 also lists criteria for anchor Appendix D of ACI 318-02 also lists criteria for anchor 
rods to prevent “failure due to lateral bursting forces at therods to prevent “failure due to lateral bursting forces at the
anchor head.” These lateral bursting forces are associatedanchor head.” These lateral bursting forces are associated
with tension in the anchor rods. The failure plane or surfacewith tension in the anchor rods. The failure plane or surface
in this case is assumed to in this case is assumed to be cone shaped and radiating frombe cone shaped and radiating from
the anchor head to the adjacent free edge or side of the con-the anchor head to the adjacent free edge or side of the con-
crete structurecrete structure. . This is This is illustrated in illustrated in Figure 9.1.5. Figure 9.1.5. It is It is rec-rec-
ommended to use a minimum side coverommended to use a minimum side cover cc11 of 6 anchor of 6 anchor diameters for anchor rods conforming to ASTM F1554diameters for anchor rods conforming to ASTM F1554
Grade 36 to avoid problems with side face breakout. AsGrade 36 to avoid problems with side face breakout. As
with the pullout stress cones, overlapping of the stresswith the pullout stress cones, overlapping of the stress
cones associated with these lateral bursting forces is con-cones associated with these lateral bursting forces is con-
sidered in Appendix D. Use of washer plates can be benefi-sidered in Appendix D. Use of washer plates can be benefi-
cial by increasing the bearing area that increases the side-cial by increasing the bearing area that increases the side-
face blowout strength.face blowout strength.
For the common case of four anchor rods in tension in aFor the common case of four anchor rods in tension in a
footing, a mat, or a wide pier, where a full breakout conefooting, a mat, or a wide pier, where a full breakout cone
can be achieved, Figure 9.1.6 provides a means of deter-can be achieved, Figure 9.1.6 provides a means of deter-
mining the anchor size, and then determining the neededmining the anchor size, and then determining the needed
anchor depth following the proposed limit states describedanchor depth following the proposed limit states describedearlier. The concrete breakout capacities assume the con-earlier. The concrete breakout capacities assume the con-
crete to be uncracked. The designer should refer to ACIcrete to be uncracked. The designer should refer to ACI
318-02 to determine if the concrete should be taken as318-02 to determine if the concrete should be taken as
cracked or uncracked. If the concrete is considered cracked,cracked or uncracked. If the concrete is considered cracked,
3030 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
00 22 44 66 88 1100 1122 1144 1166 1188 2200 2222 2244
1010
2020
3030
4040
5050
6060
7070
8080
9090
100100
110110
120120
130130
140140
150150
160160
170170
5/8"5/8"
Dia.Dia.
3/4"3/4"
Dia.Dia.
7/8"7/8"
Dia.Dia.
1" Dia.1" Dia.
1 1/8"1 1/8"
Dia.Dia.
1 1/4"1 1/4"
Dia.Dia.
Steel: 1.25Steel: 1.25φφ A  A FF
withwith φφ=0.9=0.9
Concrete:Concrete: φφN N as as given given in in Example Example 9.4.19.4.1
Concrete Uncracked (Concrete Uncracked (ψ ψ    = = 1.25)1.25)
Concrete Strength f' = 4000 psiConcrete Strength f' = 4000 psi
   Concrete Concrete BreakoutBreakout
   70% 70% Concrete Concrete BreakoutBreakout
 Anchor Rods F  Anchor Rods F = 36ksi= 36ksi
33
cc
S xS = 4x4S xS = 4x4
S xS = 6x6 and 4x8S xS = 6x6 and 4x8
S xS = 8x8S xS = 8x8
and 6x10and 6x10
S xS = 8x16S xS = 8x16
S xS = 8x8 and 6x10S xS = 8x8 and 6x10
S xS = 4x4S xS = 4x4
S xS = 8x16S xS = 8x16
S xS = 6x6 and 4x8S xS = 6x6 and 4x8
hh
SS
SS
22 11
   U   U
   l   l   t   t   i   i  m  m
  a  a
   t   t  e  e
   U   U
  p  p
   l   l   i   i   f   f   t   t
   F   F
  o  o
  r  r  c  c
  e  e
 , ,
   k   k
   i   i  p  p
  s  s
 Anchor Embedm Anchor Embedment, h ent, h , inche, inchessef ef 
ef ef 
yy
1 1 22
    
1 1 22
1 1 22
1 1 22
1 1 22
1 1 22
1 1 22
1 1 22
se se yy
cbgcbg
 Fig. 9.1.6  Fig. 9.1.6 Capacity of 4-Anchor Rods Without Edge Distance ReductionCapacity of 4-Anchor Rods Without Edge Distance Reduction
    
such thatsuch that ψ ψ 33 equals 1.0, then eighty percent of the concreteequals 1.0, then eighty percent of the concrete
capacity values should bcapacity values should be used. e used. Application of this FigureApplication of this Figure
is illustrated in Example 9.4.1.is illustrated in Example 9.4.1.
9.9.22 ReResisiststining Shg Sheaearr FoForrceces Uss Usining Ag Ancnchohorr RoRodsds
Appendix B of ACI 349-85 (ACI, 1985) and ACI 349-97Appendix B of ACI 349-85 (ACI, 1985) and ACI 349-97
(ACI, 1997) used ‘she(ACI, 1997) used ‘shear-ar-frictifriction’on’ for transffor transferrinerring shear g shear 
from the anchor from the anchor rods to the concrete. rods to the concrete. This procedure wasThis procedure was
used in the previous veused in the previous version of this design guide. rsion of this design guide. AppendixAppendix
B of ACI 349-01 and Appendix D of ACI 318-02 bothB of ACI 349-01 and Appendix D of ACI 318-02 both
employ the CCD method to evaluate the concrete breakoutemploy the CCD method to evaluate the concrete breakout
capacity from shear forces resisted by anchor rods. For thecapacity from shear forces resisted by anchor rods. For the
typical cast-in-place anchor group used in building con-typical cast-in-place anchor group used in building con-
struction the shear capacity determined by concrete break-struction the shear capacity determined by concrete break-
out as illustrated in Figure 9.2.1 is evaluated asout as illustrated in Figure 9.2.1 is evaluated as
wherewhere
cc11 = the edge distance in the direction of load as illus-= the edge distance in the direction of load as illus-
trated in Figure 9.2.1.trated in Figure 9.2.1.
 = the embedment depth.= the embedment depth.
d d oo = the bar diameter.= the bar diameter.
TypicallyTypically //d d oo becomes 8 since the  becomes 8 since the load bearingload bearing
length is limited to 8length is limited to 8d d oo..
φφ == 0.0.7070
ψ ψ 55 == 1.0 (all anchors1.0 (all anchors at same load).at same load).
ψ ψ 77 == 1.4 (uncracked or 1.4 (uncracked or with adequate supplementarywith adequate supplementary
reinforcement).reinforcement).
 A Avovo == 4.4.55cc11
22 (the area of the full shear cone for a single(the area of the full shear cone for a single
anchor as shown in Vanchor as shown in View A-Aiew A-A of Figure 9.2.1).of Figure 9.2.1).
 A Avv == the total breakout shear area the total breakout shear area for a single anchor for a single anchor or or a group of anchors.a group of anchors.
ψ ψ 66 == a modifier to ra modifier to reflecting the capacity eflecting the capacity reductionreduction
when side cover limits the size of the breakoutwhen side cover limits the size of the breakout
cone.cone.
It is recommended that the bar diameter,It is recommended that the bar diameter, d d oo, used in the, used in the
square root term of thesquare root term of the V V bb expression, be limited to a maxi-expression, be limited to a maxi-
mum of 1.25 in. mum of 1.25 in. based on recent research results. If the edgebased on recent research results. If the edge
distancedistance cc11 is large enough, then the anchor rod shear capac-is large enough, then the anchor rod shear capac-
ity will govern. This capacity is given asity will govern. This capacity is given as φφnn0.60.6 A A se se f  f ut ut  ==
0.390.39nAnA se se f  f ut ut  withwith φφ = 0.65 where= 0.65 where  f  f ut ut  is the specified tensileis the specified tensile
strength of the anchor steel, andstrength of the anchor steel, and nn is the number of anchors.is the number of anchors.
Where anchors are used with a built-up grout pad, theWhere anchors are used with a built-up grout pad, the
anchor capacity should be multiplied by 0.8 anchor capacity should be multiplied by 0.8 which results inwhich results in
an anchor shear capacity of 0.31an anchor shear capacity of 0.31nAnA se se f  f ut ut . . Appendix B of Appendix B of ACIACI
349-01 does permit the sharing of the anchor shear integrity349-01 does permit the sharing of the anchor shear integrity
with the friction developed from factored axial and flexuralwith the friction developed from factored axial and flexural
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 3131
0.20.2
1.51.5
1177bb oo cc
oo
V V d d f f cc
d d 
    
==    ′′        
ll
1.51.5
6 6 111100..44 vv
ccbbgg oo cc
vovo
 A A
V V d d f f cc
 A A
φ φ = = ψ ψ     ′′
 Anchor Rod Anchor RodFree Edge Of Free Edge Of 
ConcreteConcrete
VVStress Half-ConeStress Half-Cone
CC11
Top Of Top Of 
ConcreteConcrete
11..55CC 11..55CC11 11
1.5C1.5C
11
11
1.51.5
View A-AView A-A
 A A
 A A
 Fig 9.2.1  Fig 9.2.1 Concrete Breakout Cone for Shear Concrete Breakout Cone for Shear 
SS
CC SS
11
BB
BB
ii
S/SS/S
C C /S /S For For 
B B To To ControlControl
11
oo
11
11 11
oo
00..55 > > 11..5599
22//33 > > 11..5566
11..00 > > 11..5500
11..55 > > 11..4400
22..00 > > 11..3300
11
11..55 11..55
11
 Fig. 9.2.2  Fig. 9.2.2 Concrete Breakout Surfaces for GroConcrete Breakout Surfaces for Group Anchorsup Anchors
 Fig. 9.2.3  Fig. 9.2.3 Concrete Reinforcement to ImprConcrete Reinforcement to Improve Shearove Shear
Capacity Where Edge Distance is Limited Capacity Where Edge Distance is Limited 
5 5 6 6 77
vv
ccbbgg bb
vovo
 A A
V V V V 
 A A
φ φ = = φ φ ψ ψ ψ ψ ψ  ψ  
    
load. load. AA coefficient coefficient of of friction of friction of 0.4 is 0.4 is used. used. ACI 318-ACI 318-0202
Appendix D does not recognize the benefit of the friction.Appendix D does not recognize the benefit of the friction.
In evaluating the concrete breakout, one In evaluating the concrete breakout, one should check theshould check the
 breakout either from the  breakout either from the most deeply embedded anchors or most deeply embedded anchors or 
 breakout on the anchors closer to the edge.  breakout on the anchors closer to the edge. When breakoutWhen breakout
is being determined on the inner two anchors, the outer twois being determined on the inner two anchors, the outer two
anchors should be considered to caranchors should be considered to carry the same load. ry the same load. WhenWhen
the concrete breakout is considered from the outer twothe concrete breakout is considered from the outer two
anchors, all of shear is to be taken by the outer anchors.anchors, all of shear is to be taken by the outer anchors.
Shown in Figure 9.2.2 are the two potential breakout sur-Shown in Figure 9.2.2 are the two potential breakout sur-
faces and an indication of which will control, based onfaces and an indication of which will control, based on
anchor location relative to the edge distance.anchor location relative to the edge distance.
To ensure that shear yield of the anchor will control,To ensure that shear yield of the anchor will control,
design the concrete breakout shear capacity to meet or design the concrete breakout shear capacity to meet or 
exceed the minimum of 1.25exceed the minimum of 1.25φφV V  y y usingusing φφ = 0.9 to obtain= 0.9 to obtain
1.25(0.9)(0.61.25(0.9)(0.6 A A se se F  F  y y) = 0.675) = 0.675  A A se se F  F  y y. . An An appreciable appreciable edgeedge
distance is required to achieve a ductile shear failure. For distance is required to achieve a ductile shear failure. For 
example, with 4 anchor rods, withexample, with 4 anchor rods, with F  F  y y = 36 ksi, with a 4 in.= 36 ksi, with a 4 in.
 by 4 in. patter by 4 in. pattern and a 4 in. edge distann and a 4 in. edge distance (ce (cc11 in Figure 9.2.2),in Figure 9.2.2),
full anchor shear capacity can be reached for ½ in. diame-full anchor shear capacity can be reached for ½ in. diame-
ter anchors provided that no benefit exists from the fric-ter anchors provided that no benefit exists from the fric-
tional shear resistance. For full shear capacity oftional shear resistance. For full shear capacity of 55//88 in.in.
diameter (diameter ( F  F  y y = 36 ksi) anchors a 5 in. edge distance is= 36 ksi) anchors a 5 in. edge distance is
required while a 7 in. edge distance is required for ¾ in.required while a 7 in. edge distance is required for ¾ in.
diameter anchors with no frictional benefit.diameter anchors with no frictional benefit.
In many cases it is necessary to use reinforcement toIn many cases it is necessary to use reinforcement to
anchor the breakout cone in order to achieve the shear anchor the breakout cone in order to achieve the shear 
capacity as well as the dcapacity as well as the ductility desired. uctility desired. An example of thisAn example of this
is illustrated in Figure is illustrated in Figure 9.2.3. 9.2.3. The ties placed The ties placed atop piers asatop piers as
required in Section 7.10.5.6 of ACI 318-02 and illustratedrequired in Section 7.10.5.6 of ACI 318-02 and illustrated
in Example 9.4.2 can also be used structurally to transfer in Example 9.4.2 can also be used structurally to transfer 
the shear from the anchorthe shear from the anchors to the piers. s to the piers. If the shear is small,If the shear is small,
the best approach is to simply design for the non-ductilethe best approach is to simply design for the non-ductile
concrete breakout using the 70 percent factor noted earlier.concrete breakout using the 70 percent factor noted earlier.
Careful consideration should be given to the size of theCareful consideration should be given to the size of the
anchor rod holes in the base plate, when transferring shear anchor rod holes in the base plate, when transferring shear 
forces from the column base plate to the anchor rods. Theforces from the column base plate to the anchor rods. The
designer should use the recommended anchor rod holedesigner should use the recommended anchor rod hole
diameters and minimum washer diameters, which can bediameters and minimum washer diameters, which can be
found on page14-27 of the AISC 3rd editionfound on page 14-27 of the AISC 3rd edition  LRFD Man- LRFD Man-
ual of Steel Constructionual of Steel Construction (AISC, 2001). These recom-(AISC, 2001). These recom-
mended hole sizes vary with rod diameter, and aremended hole sizes vary with rod diameter, and are
considerably largeconsiderably larger than normal r than normal bolt hole sizes. bolt hole sizes. If slip of If slip of 
the column base, before bearing, against the anchor rods isthe column base, before bearing, against the anchor rods is
of concern, then the designer should consider using plateof concern, then the designer should consider using plate
washers between the base plate and the anchor rod nut.washers between the base plate and the anchor rod nut.
Plate washers, with holesPlate washers, with holes 11//1616 in. larger than the anchor rods,in. larger than the anchor rods,
can be welded to the base plate so that minimal slip wouldcan be welded to the base plate so that minimal slip would
occur. Alternatively, a setting plate could be used, and theoccur. Alternatively, a setting plate could be used, and the
 base  base plate plate of of the the column column welded welded to to the the setting setting plate. plate. TheThe
setting plate thickness must be determined for proper bear-setting plate thickness must be determined for proper bear-
ing against the anchor rods.ing against the anchor rods.
9.9.33 ReResisiststining Sg Shehearar FoForrceces s ThThrrouough gh BeBeararining ag andnd
with Reinforcing Barswith Reinforcing Bars
Shear forces can be transferred in bearing by the use of Shear forces can be transferred in bearing by the use of 
shear lugs or by embedding the column in the foundation.shear lugs or by embedding the column in the foundation.
These methods are illustrated in Figure 9.3.1.These methods are illustrated in Figure 9.3.1.
Appendix B of ACI 349-01 does permit the use of con-Appendix B of ACI 349-01 does permit the use of con-
finement and of shear friction in combination with bearingfinement and of shear friction in combination with bearing
for transferring shear from anchor rods into the concrete.for transferring shear from anchor rods into the concrete.
The commentary to ACI 349-02 suggests that this mecha-The commentary to ACI 349-02 suggests that this mecha-
nism is developed as follows:nism is developed as follows:
1.1. SheShear is ar is iniinitialtially trly transansferferred tred throhrough tugh the anhe anchochor ror rods tods to
the grout or concrete by bearing augmented by shear the grout or concrete by bearing augmented by shear 
resistance from confinement effects associated withresistance from confinement effects associated with
tension anchors and external concurrent axial load.tension anchors and external concurrent axial load.
2.2. SheShear tar then hen proprogregressesses ins into a sto a sheahear-r-frifrictiction moon mode.de.
The recommended bearing limitThe recommended bearing limit φφ P  P urbg urbg   per  per SectionSection
B.4.5.2 of ACI 349-01 Appendix B isB.4.5.2 of ACI 349-01 Appendix B is φφ1.31.3 f  f ′′cc A A . . Using Using aa φφ
consistent with ASCE-7 load factors useconsistent with ASCE-7 load factors use φφ P  P urbg urbg = 0.80= 0.80 f  f ′′cc A A
for shear lugs.for shear lugs.
 A A = embedded area of the shear lug (this does not= embedded area of the shear lug (this does not
include the portion of the lug in contact with the groutinclude the portion of the lug in contact with the grout
above the pier).above the pier).
For bearing against an embedded base plate or columnFor bearing against an embedded base plate or column
section where the bearing area is adjacent to the concretesection where the bearing area is adjacent to the concrete
surface it is recommended thatsurface it is recommended that φφ P  P ubrg ubrg  = 0.55= 0.55 f  f ′′cc A Abrg brg consis-consis-
tent with ACI 318-02.tent with ACI 318-02.
According to the Commentary of Appendix B of ACIAccording to the Commentary of Appendix B of ACI
349-01, the anchorage shear strength due to confinement349-01, the anchorage shear strength due to confinement
can be taken ascan be taken as φφ K  K cc(( N  N  y y − − P  P aa), with), with φφ equal to 0.75, whereequal to 0.75, where N  N  y y
3232 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
 Fig. 9.3.1  Fig. 9.3.1 Transfer of Base Shears ThrouTransfer of Base Shears Through Bearing gh Bearing 
    
is the yield strength of the tension anchors equal tois the yield strength of the tension anchors equal to nAnA se se F  F  y y,,
andand P  P aa is the factored external axial load on the anchorage.is the factored external axial load on the anchorage.
(( P  P aa is positive for tension and negative for compression).is positive for tension and negative for compression).
This shear strength due to confinement considers the effectThis shear strength due to confinement considers the effect
of the tension anchors and external loads acting across theof the tension anchors and external loads acting across the
initial shear initial shear fracture planes. fracture planes. WhenWhen P  P aa is negative, one mustis negative, one must
 be  be assured assured that that thethe  P  P aa will actually be present while thewill actually be present while the
shear force is occurring. Based on ACI 349-01 Commentaryshear force is occurring. Based on ACI 349-01 Commentary
useuse Kc Kc = 1.6.= 1.6.
In summary the lateral resistance can be expressed as:In summary the lateral resistance can be expressed as:
φφ P  P nn =0.80=0.80 f  f ′′cc A A + 1.2(+ 1.2( N  N  y y − − P  P aa) for shear lugs and) for shear lugs and
φφ P  P nn =0.55=0.55 f  f ′′cc A Abrg brg + 1.2(+ 1.2( N  N  y y − − P  P aa) for bearing on a column) for bearing on a column
or the side of a base plate.or the side of a base plate.
If the designer wishes to use shear-friction capacity asIf the designer wishes to use shear-friction capacity as
well, the provisions of ACI 349-01 can be followed.well, the provisions of ACI 349-01 can be followed.
Additional comments related to the use of shear lugs areAdditional comments related to the use of shear lugs are
 provided below: provided below:
1.1. For For sheshear lar lugs ugs or cor coluolumn emn embembedmedments nts beabearinring in g in thethe
direction of a free edge of the direction of a free edge of the concrete, Appendix B of concrete, Appendix B of 
ACI 349-01 states that in addition to considering bear-ACI 349-01 states that in addition to considering bear-
ing failure in the concrete, “the concrete design shear ing failure in the concrete, “the concrete design shear 
strength for the lug shall be determined based on a uni-strength for the lug shall be determined based on a uni-
form form tensile tensile stress stress of of acting acting on on an an effectiveeffective
stress area defined by projecting a 45° plane from thestress area defined by projecting a 45° plane from the
 bearing edge of the shear lug to the free surfa bearing edge of the shear lug to the free surface.” ce.” TheThe
 bearing area  bearing area of the of the shear lug shear lug (or column (or column embedment)embedment)
is to be excluded from the projected area. Use ais to be excluded from the projected area. Use a φφ
equal to 0.75. This criterion may control or limit theequal to 0.75. This criterion may control or limit the
shear capacity of the shear lug or column embedmentshear capacity of the shear lug or column embedment
details in concrete piers.details in concrete piers.
2.2. ConConsidsideraeration tion shoshould uld be gbe giveiven to n to benbendinding in g in the the basbasee
 plate resulting  plate resulting from forces from forces in the in the shear lug. shear lug. This canThis can
 be  be of of special special concern concern when when the the base base shears shears (most(most
likely due to bracingforces) are large and bendinglikely due to bracing forces) are large and bending
from the force on the shear lug is about the weak axisfrom the force on the shear lug is about the weak axis
of the column. of the column. As a rule of As a rule of thumb, the author gener-thumb, the author gener-
ally requires the base plate to be of equal or greater ally requires the base plate to be of equal or greater 
thickness than the shear lug.thickness than the shear lug.
3.3. MulMultipltiple she shear ear luglugs mas may be y be useused to d to resresist ist larlarge sge sheahear r 
forces. forces. Appendix B of Appendix B of ACI 349-01 prACI 349-01 provides criteriaovides criteria
for the design and spacing of multiple shear lugs.for the design and spacing of multiple shear lugs.
AA typical design for a typical design for a shear lug is illustrated in shear lug is illustrated in ExampleExample
9.4.3. 9.4.3. The designer The designer may want to cmay want to consider resisting shonsider resisting shear ear 
forces with the shear lugs welded to a setting template. Theforces with the shear lugs welded to a setting template. The
setting templates are cast with the anchor rods. Thesetting templates are cast with the anchor rods. The
columns are then set with conventional shim stacks. Tocolumns are then set with conventional shim stacks. To
complete the shear transfer, shear transfer bars are weldedcomplete the shear transfer, shear transfer bars are welded
to the base plate and to the setting template. The settingto the base plate and to the setting template. The setting
template has grout holes and thus allows good consolida-template has grout holes and thus allows good consolida-
tion of the concrete around the shear lugs.tion of the concrete around the shear lugs.
To complete the discussion on anchorage design, transfer To complete the discussion on anchorage design, transfer 
of shear forces to reinforcement using hairpins or tie rodsof shear forces to reinforcement using hairpins or tie rods
will be addressed. will be addressed. Hairpins are typically Hairpins are typically used to transfused to transfer er 
load to the floor sload to the floor slab. lab. The friction between the The friction between the floor slabfloor slab
and the subgrade is used in resisting the column base shear and the subgrade is used in resisting the column base shear 
when individual footings are not capable of resisting hori-when individual footings are not capable of resisting hori-
zontal forces. zontal forces. The column base shears The column base shears are transferred frare transferred fromomthe anchor rods to the hairpin (as shown in Figure 9.3.2)the anchor rods to the hairpin (as shown in Figure 9.3.2)
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 3333
44 cc f   f  φφ    ′′
  
 Fig. 9.3.2  Fig. 9.3.2 Typical Detail Using Hairpin Bars.Typical Detail Using Hairpin Bars.
 Fig. 9.3.3  Fig. 9.3.3 Alternate Hairpin DetailAlternate Hairpin Detail Fig. 9.4.1 Fig. 9.4.1 Example 9.4.1Example 9.4.1
Large Spread FootingLarge Spread Footing
f' f' For For ConcreteConcrete
= 4000 psi= 4000 psi
cc
P P = = 56k56k
(Due To WL)(Due To WL)
P = 22kP = 22k
DLDL
UPLIFTUPLIFT
    
through bearing. through bearing. Problems have Problems have occurred with occurred with the eccen-the eccen-
tricity between the base plate and the hairpin due to bend-tricity between the base plate and the hairpin due to bend-
ing in the anchor rods after the friction capacity ising in the anchor rods after the friction capacity is
exceeded. exceeded. This problem can be This problem can be avoided as shown avoided as shown in Figurein Figure
9.3.3 or 9.3.3 or by providing by providing shear lugs. shear lugs. Because hairpins Because hairpins relyrely
upon the frictional restraint provided by the floor slab, spe-upon the frictional restraint provided by the floor slab, spe-
cial consideration should be given to the location and typecial consideration should be given to the location and type
of control and construction joints used in the floor slab toof control and construction joints used in the floor slab to
assure no interruption in load transfer, yet still allowing theassure no interruption in load transfer, yet still allowing the
slab to move.slab to move.
Tie rods are typically used to counteract large shear Tie rods are typically used to counteract large shear 
forces associated with gravity loads on rigid frame struc-forces associated with gravity loads on rigid frame struc-
tures. tures. When using When using tie rods tie rods with large with large clear span clear span rigidrigid
frames, consideration should be given to elongation of theframes, consideration should be given to elongation of the
tie rods and to the impact of these elongations on the frametie rods and to the impact of these elongations on the frame
analysis and design. analysis and design. In addition significant amounts of In addition significant amounts of sag-sag-
ging or bowing should be removed before tie rods areging or bowing should be removed before tie rods are
encased or covered, since the tie rod will tend to straightenencased or covered, since the tie rod will tend to straighten
when tensioned.when tensioned.
9.4 9.4 Column Column Anchorage Examples Anchorage Examples (Pinned Base)(Pinned Base)
EXAMPLE 9.4.1:EXAMPLE 9.4.1:
Column Anchorage Column Anchorage forfor TTensile Loads (LRFD)ensile Loads (LRFD)
Design a base plate and anchorage for aDesign a base plate and anchorage for a WW1010××45 column45 column
subjected to a net uplift as a result of the loadings shown insubjected to a net uplift as a result of the loadings shown in
Figure 9.4.1:Figure 9.4.1:
 Procedur Procedure:e:
1.1. DeDeterterminmine the the dee desisign ugn uplplifift on tt on the che cololumumn.n.
2.2. SeSelelect tct the the typype ane and nud numbmber oer of anf anchchor ror rodods.s.
3.3. DeteDetermirmine tne the ahe apprppropropriate iate basbase ple plate ate thithicknckness ess andand
welding to transfer the uplift forces from the columnwelding to transfer the uplift forces from the column
to the anchor rods.to the anchor rods.
4.4. DeteDetermirmine tne the mhe methethod fod for dor deveeveloploping ting the ahe anchnchor ror rodsods
in the concrete in the spread footing.in the concrete in the spread footing.
5.5. Re-Re-evaevalualuate thte the ane anchochoragrage if te if the che coluolumn is mn is on a on a 20 in20 in..
 by 20 in.  by 20 in. pier.pier.
Solution:Solution:
1.1. FacFactortored ed upluplift ift = 1= 1.6(.6(56)56)-0.-0.9(29(22) 2) = = 69.8 69.8 kipkipss
2.2. UsUse fe fouour ar ancnchohor rr rodods (s (minminimuimum pm per er OSOSHAHA rereququirire-e-
ments).ments).
T/Rod T/Rod = 69.8/4 = 17.45 kips.= 69.8/4 = 17.45 kips.
Using an ASTM F1554 Grade 36 material, select aUsing an ASTM F1554 Grade 36 material, select a
77//88 in. diameter rod.in. diameter rod.
The design strength is the lower value of:The design strength is the lower value of:
φφ F  F  y y A Aqq = (0.9)(36)(0.60) = 19.44 kips= (0.9)(36)(0.60) = 19.44 kips
oror φφ F  F uu A Aee = (0.75)(58)(0= (0.75)(58)(0.462) = .462) = 20.10 kips 20.10 kips o.k.o.k.
 Note:  Note: The The anchor anchor rods rods are are positioned positioned inside inside the the col-col-
umn profile and rod forces are not extremely large;umn profile and rod forces are not extremely large;
therefore, prying forces are negligible.therefore, prying forces are negligible.
3.3. The The rodrods ars are poe positisitioneoned ind insidside the the coe column lumn proprofilfile wite withh
a 4 in. square pattern. To simplify the analysis, con-a 4 in. square pattern. To simplify the analysis, con-servatively assume the tensile loads in servatively assume the tensile loads in the anchor rodsthe anchor rods
generate one-way bending in the base plate about thegenerate one-way bending in the baseplate about the
web of web of the column. the column. This assumption is This assumption is illustrated byillustrated by
the rod load distributions shown in Figure 9.4.2.the rod load distributions shown in Figure 9.4.2.
 M  M  y y in the base plate equals the rod force times tin the base plate equals the rod force times the lever he lever 
arm to the column web face.arm to the column web face.
The effective width of base plate for resistingThe effective width of base plate for resisting M  M  y y at theat the
face of web =face of web = bbeff eff ..
Using a 45° distribution for the rod loads,Using a 45° distribution for the rod loads,
 F  F  y y = 36 ksi= 36 ksi
3434 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
4"4"
4"4"
 Fig. 9.4.2  Fig. 9.4.2 Rod Load DistributionRod Load Distribution
0.3500.350
1177..4455 22 3311..885 5 iinn..--kkiippss
22
 y y M  M 
       = = − − ==        
( ( ))..
0.3500.350
22 22 33..665 5 iinn..
22
eff eff bb
       = = − − ==        
22
44
eff eff 
 y y
b b t t 
 Z  Z     ==
( ( ))
( ( ))' ' ..
44 y y
req d req d 
eefff f yy
 M  M 
t t 
b b F F 
==
φφ
    
Use a 1Use a 111//88 in. thick plate (in. thick plate ( Fy Fy = 36 ksi).= 36 ksi).
For welding of the column to the base plate:For welding of the column to the base plate:
Maximum weld load =Maximum weld load =
Minimum weld for a 1Minimum weld for a 111//88 in. thick base plate =in. thick base plate = 55//1616 in.in.
(T(Table J2.4 able J2.4 ofof LRFD Specificat LRFD Specificationion).).
Design weld load per in. for aDesign weld load per in. for a 55//1616 in. fillet weld within. fillet weld with
E70 electrode:E70 electrode:
= (5/16)(0.707)(0.75)(70) = 11.6 k/in.= (5/16)(0.707)(0.75)(70) = 11.6 k/in.
4.78 < 11.604.78 < 11.60
Check web:Check web:
φφ P  P nn ==    φφbbeff eff (2)(2) F  F  y yt t ww
== (0.(0.9)(9)(3.63.65)(5)(2)(2)(36)36)(0.(0.35)35)
== 8822..8 8 kkiippss
82.8 82.8 > > (4)(17.5) (4)(17.5) o.k.o.k.
4.4. As nAs noteoted ead earlierlier, r, this this colcolumn umn is ais anchnchoreored in d in the the middmiddlele
of a large of a large spread footing. spread footing. Consequently, Consequently, there are nothere are no
edge constraints on the concrete tensile cones andedge constraints on the concrete tensile cones and
there is no concern regarding edge distance to preventthere is no concern regarding edge distance to prevent
lateral breakout of the concrete.lateral breakout of the concrete.
To ensure a ductile failure in the case of overload,To ensure a ductile failure in the case of overload,
design the embedment of the anchor rods to yielddesign the embedment of the anchor rods to yield
some prior to concrete breakout. Forsome prior to concrete breakout. For 77//88 in. diameter in. diameter 
F1554 Grade 36 rods, this is equal toF1554 Grade 36 rods, this is equal to
(1.25)(0.9)(0.462)(36) = 18.7 kips/rod.(1.25)(0.9)(0.462)(36) = 18.7 kips/rod.
Try using a 3.5 in. hook on the embedded end of theTry using a 3.5 in. hook on the embedded end of the
anchor rod to develop the rod.anchor rod to develop the rod.
Based on uniform bearing on the hook, the hook bear-Based on uniform bearing on the hook, the hook bear-
ing capacity per ACI 318-02 Appendix Ding capacity per ACI 318-02 Appendix D
== φφ (0.9)((0.9)( f f ′′cc)()(d d oo)()(eehh)()(ψ ψ 44))
wherewhere
φφ == 00..7700
 f f ′′cc == conconcrecrete te comcomprepressissive ve strstrengengthth
d d oo == hhooook dk diiaammeetteer r  
eehh == hohook pok prrojojeectctioionn
ψ ψ 44 == cracrackicking ng facfactor tor (1.(1.0 f0 for or cracrackecked, d, 1.4 1.4 forfor
uncracked concrete)uncracked concrete)
HooHook beark bearing caping capaciacityty == 0.70.70(00(0.9).9)(40(4000)00)(7/(7/8)8)
(3.5-0.875)(1.4)(3.5-0.875)(1.4)
== 8811000 0 llbb
== 8.18.10 kip0 kips < 18s < 18.7 ki.7 kips N.ps N.GG..
Thus a 3.5 in. hook is not capable of developing theThus a 3.5 in. hook is not capable of developing the
required tensile required tensile force in force in the rod. the rod. Therefore, use Therefore, use aa
heavy hex nut to develop the anchor rod.heavy hex nut to develop the anchor rod.
To achieve a concrete breakout strength,To achieve a concrete breakout strength, φφ N  N cbg cbg , that, that
exceeds the desired 4(18.7) = 74.8 kip steel capacity,exceeds the desired 4(18.7) = 74.8 kip steel capacity,
the embedment depth must be at least 13 in. deter-the embedment depth must be at least 13 in. deter-
mined by trial and mined by trial and error or error or from Figure from Figure 9.1.6.9.1.6.
Per ACI 318-02 Appendix D, the concrete breakoutPer ACI 318-02 Appendix D, the concrete breakout
strengthstrength
andand
wherewhere
φφ == 00..7700
ψ ψ 33 == 1.21.25 con5 considsideriering the cng the conconcretrete to be une to be uncracrackeckedd
hhef ef  == 113 3 iinn..
 A A N  N  == conconcrecrete bte breareakoukout cot cone ane area rea for for grogroupup
== (3(3(1(13) 3) + 4+ 4)()(3(3(1313) + ) + 4) 4) = 1= 1848499
 A A No No == conconcrecrete brte breakeakout cout cone aone area frea for sior singlngle ance anchor hor 
= 9(13)= 9(13)22 = 1521= 1521
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 3535
( )( )
( ) ( )( ) ( )' ' ..
3311..99 44
1.04 in.1.04 in.
33..6655 00..99 3366
req d req d t t     = = ==
// 1177..55
4.78k/in.4.78k/in.3.653.65eff eff 
T T BBoolt lt  
bb = = ==
1.51.5
33= = 224 4 ffoor 1r 11 1 iinn.. N  N 
ccbbgg cc eeff eef  f  
 No No
 A A
 N  N f f h h hh
 A A
φ φ φφψ ψ ≤≤′′
5/5/ 33
33= = 116 6 ffoorr N  N 
ccbbgg cc eeff eef  f  
 No No
 A A
 N  N f f h h hh
 A A
φ φ φψ φψ     ′′ > 11 in.> 11 in.
5/5/ 33 18491849
   = = 0.700.70((1.251.25)()(16)16) 0.000.004(134(13))
15211521
77.4 kips77.4 kips
cbg cbg  N  N 
       
φφ            
==
11
1.51.5
PotentialPotential
Failure PlaneFailure Plane
 Anchor  Anchor RodRod
#6 Bar #6 Bar 
g = 7.9"g = 7.9"
L = 17.4"L = 17.4"
1 1/2" Cover 1 1/2" Cover 
ee hh
ef ef 
hh
ef ef ee
= L = L + cover + + cover + g/1.5g/1.5
= 17.4 + 1.5 + 7.9/1.5= 17.4 + 1.5 + 7.9/1.5
 Fig. 9.4.3  Fig. 9.4.3 Embedment Depth for Transfer to Reinforcing BarsEmbedment Depth for Transfer to Reinforcing Bars
    
From Figure 9.1.6 for a 4 in. by 4 in. spacing of From Figure 9.1.6 for a 4 in. by 4 in. spacing of 
anchors, with the ultimate tension of 69.8 kips, ananchors, with the ultimate tension of 69.8 kips, an
anchor embedment of 15.5 in. would be required toanchor embedment of 15.5 in. would be required to
achieve the 70 percent breakout capacity in achieve the 70 percent breakout capacity in which casewhich case
a ductile ana ductile anchor failure chor failure would not be would not be required. required. ThisThis
embedment would be satisfactory if the anchors wereembedment would be satisfactory if the anchors were
1 in. diameter F1554 1 in. diameter F1554 Grade 36 or larger. WGrade 36 or larger. With theith the 77//88 in.in.
diameter anchors a 13 in. embedment is adequate todiameter anchors a 13 in. embedment is adequate to
achieve the anchor capacity considering the full break-achieve the anchor capacity considering the full break-
out capacity shown as dashed lines in Figure 9.1.6.out capacity shown as dashed lines in Figure 9.1.6.
5.5. If tIf the ahe anchnchors ors werwere inse installtalled in ed in a 20 a 20 in. sin. squaquare pre pier ier thethe
concrete breakout strength would be limited by theconcrete breakout strength would be limited by the
 pier  pier cross cross section. section. With an With an 8 8 in. in. maximum maximum edge edge dis-dis-
tance the effectivetance the effective hhef ef need be only 8/1.5 = 5.33 in. toneed be only 8/1.5 = 5.33 in. to
have the breakout cone area equal this pier cross sec-have the breakout cone area equal this piercross sec-
tional area. This leads to ational area. This leads to a
Therefore the uplift strength is 0.7(27.4) = 19.2 kipsTherefore the uplift strength is 0.7(27.4) = 19.2 kips
 based  based on on the the concrete concrete only. only. Thus, Thus, it it is is necessary necessary toto
transfer the anchor load to the vertitransfer the anchor load to the vertical reinforcing steelcal reinforcing steel
in the pier. The requiredin the pier. The required
The minimum 4-#7 bars required per ACI 318-02 inThe minimum 4-#7 bars required per ACI 318-02 in
the pier are adequate to take this tension. the pier are adequate to take this tension. With the barsWith the bars
located in the corners of the piers use a lateral offsetlocated in the corners of the piers use a lateral offset
distancedistance g  g = [(20 in.= [(20 in.−− 4 in.)/24 in.)/2 −− 2.4 in.]2.4 in.]
Using a Class B splice factor with a 1.3 value and withUsing a Class B splice factor with a 1.3 value and with
a development length of the #7 bar equal to 24.9 in.,a development length of the #7 bar equal to 24.9 in.,
computecompute l l ee from the ratiofrom the ratio
  ee = 17.4 = 17.4 in. in. Therefore minimum Therefore minimum requiredrequired hhef ef = 17.4 += 17.4 +
1.5 + 7.9/1.5 = 24.2 in. as illustrated on Figure 9.4.3.1.5 + 7.9/1.5 = 24.2 in. as illustrated on Figure 9.4.3.
Select 25 in. embedment for anchors.Select 25 in. embedment for anchors.
EXAMPLE 9.4.2:EXAMPLE 9.4.2:
Column Anchorage fColumn Anchorage foror Combined TCombined Tension and Shearension and Shear
Loads Loads (Pinned (Pinned Base) Base) (LRFD)(LRFD)
Design a base plate and anchorage for theDesign a base plate and anchorage for the WW1010××45 column45 column
examined in Example 9.4.1, but with an additional nominalexamined in Example 9.4.1, but with an additional nominal
 base  base shear shear of of 23 23 kips kips due due to to wind. wind. Assume Assume a a 2 2 in. in. thick thick 
grout bed is used grout bed is used beneath the base plate. beneath the base plate. For this example,For this example,
the column is assumed to be supported on a 20 in. squarethe column is assumed to be supported on a 20 in. square
 pier. See Figure 9.4.4. pier. See Figure 9.4.4.
 Procedur Procedure:e:
1.1. DeteDeterminrmine te the he maxmaximum imum net net tentensiosion in in tn the he ancanchor hor 
rods. rods. Decide whether the tensDecide whether the tension can be traion can be transferred tonsferred to
the concrete or whether the anchors must be lappedthe concrete or whether the anchors must be lappedwith the vertical pier reinforcement.with the vertical pier reinforcement.
2.2. SeSelelect tct the the typype ane and nud numbember of ar of ancnchohor ror rodsds..
3.3. DeteDeterminrmine the the ape appropropripriate ate basbase ple plate ate thicthicknekness ass andnd
welding to transfer the uplift welding to transfer the uplift and shear forces from theand shear forces from the
column to the anchor rods.column to the anchor rods.
3636 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
DLDL
P = 22kP = 22k
UPLIFTUPLIFT
P P = = 56k56k
(Due To WL)(Due To WL)
V = 23kV = 23k
(Due To WL)(Due To WL)
cc
20 Inch Square20 Inch Square
Concrete Pier Concrete Pier 
(f' (f' = 4= 4000 psi)000 psi)
2 Inch2 Inch
GroutGrout
BedBed
 Fig.  Fig. 9.4.4 9.4.4 Column pier support Column pier support   Fig. 9.4.5  Fig. 9.4.5 Pier for Ex. 9.4.2 Showing Shear Breakout ConePier for Ex. 9.4.2 Showing Shear Breakout Cone
TT
VV
2 at 2"2 at 2"
8" Typ.8" Typ.
Breakout Line AtBreakout Line At
Side Of Pier Side Of Pier 
Breakout Line AtBreakout Line At
Center Of Pier Center Of Pier 
20"20"
20"20"5"5"
5"5"
VV
2 - #4 Ties2 - #4 Ties
22
1.51.5
22
2020
0.750.75((1.251.25)(24)(24)) 0.000.004(5.33)4(5.33)
9(5.33)9(5.33)
27.4 kips27.4 kips
cbcb N  N 
    
φ φ ==        
    
==
2269.8 kips69.8 kips
1.29 in.1.29 in.
0.9(60)0.9(60)
 s s A A    = = ==
22 77..9 9 iinn..==
1.31.3 1.3(24.9)1.3(24.9)
6699..88 44((00..66))((00..99))((6600))
ee d d 
 s s yynA nA F F 
= = ==
φφ
l l ll
    
4.4. DeteDeterminrmine whe whethether ter the she sheahear car can be n be tratransfnsferrerreded
directly to the concrete, or whether the shear must bedirectly to the concrete, or whether the shear must be
transferred to ties.transferred to ties.
Solution:Solution:
1.1. As dAs deteetermirmined ned in Ein Examxample ple 9.49.4.1, .1, the the net net upluplift ift on ton thehe
column = 69.8 kips, and as determined from the lastcolumn = 69.8 kips, and as determined from the last part  part of of Example Example 9.4.1, 9.4.1, it it is is necessary necessary to to transfer transfer thethe
tensile loading to the tensile loading to the pier vertical reinfopier vertical reinforcement. rcement. TheThe
vertical reinforcement in the pier will be larger in thisvertical reinforcement in the pier will be larger in this
case due to the moment introduced into the pier fromcase due to the moment introduced into the pier from
the applied shear.the applied shear.
2.2. AA tottotal al of of fofour ur ananchchor or rorods ds arare te to bo be ue usesed. d. ThThe se samamee
fourfour 77//88 in. diameter rods used in Example 9.4.1 couldin. diameter rods used in Example 9.4.1 could
 be used here as  be used here as well, provided twell, provided thehe
However, 1However, 111//88 in. diameter F1554 Grade 36 anchors arein. diameter F1554 Grade 36 anchors are
required in this case.required in this case.
= = 28.94 28.94 ksi ksi o.k.o.k.
3.3. PosPositioition thn the roe rods wds withiithin thn the pre profiofile ole of thf the coe column lumn withwith
a 5 in. sa 5 in. square pattern. quare pattern. Conservatively assume Conservatively assume the ten-the ten-
sile loads in the anchor rods generate one-way bend-sile loads in the anchor rods generate one-way bend-
ing in the base plate about the web of the column or ing in the base plate about the web of the column or 
assume that two way bending occurs by consideringassume that two way bending occurs by considering
 bending of the  bending of the base plate between base plate between flanges.flanges.
4.4. The The sheshear bar breareakoukout cot cone ane as vis vieweewed frd from thom the toe top of p of thethe pier  pier is is shown shown in in the the Figure Figure 9.4.5.The 9.4.5.The shear shear breakoutbreakout
force is based on all shear on the back anchors.force is based on all shear on the back anchors.
< 1.6(23)< 1.6(23)
The maximum shear of concrete pier without stirrupsThe maximum shear of concrete pier without stirrups
 per ACI 318-02 is per ACI 318-02 is
From this calculation it is obvious that the appliedFrom this calculation it is obvious that the applied
shear of 23 kips must be transferred to tie reinforce-shear of 23 kips must be transferred to tie reinforce-
ment at the top of the pier and then transferred downment at the top of the pier and then transferred down
the pier with the aid of tie reinforcement, since thethe pier with the aid of tie reinforcement, since the
shear is greater than that which can be taken by con-shear is greater than that which can be taken by con-
crete alone.crete alone.
ACI 318-02 in section 7.10.5.6 requires the use of ACI 318-02 in section 7.10.5.6 requires the use of 
either 2-#4 or 3-#3 ties as lateral reinforcement withineither 2-#4 or 3-#3 ties as lateral reinforcement within
the top 5 in. of the pier.the top 5 in. of the pier.
Per Section 12.13.2.1 of ACI 318-02, the #4 bar can bePer Section 12.13.2.1 of ACI 318-02, the #4 bar can be
developed by hooking developed by hooking around a vearound a vertical barrtical bar. . There-There-
fore 4-#4 hooks can develop 4(0.20)(60)(0.9) = 43.2fore 4-#4 hooks can develop 4(0.20)(60)(0.9) = 43.2
kips. Sincekips. Since V V uu = 1.6 (23 kips) = 36.8 kips is less than= 1.6 (23 kips) = 36.8 kips is less than
the 43.2 kips the 2-#4 tiesat the top of the pier canthe 43.2 kips the 2-#4 ties at the top of the pier can
transfer the shear into the pitransfer the shear into the pier. Wer. With #4 ties ith #4 ties at the min-at the min-
imum required spacing in shear (use 8 in.), imum required spacing in shear (use 8 in.), thethe φφV V nn for for 
the the pier pier is is , , which which equalsequals
= 82.2 kips > 36.8 kips.= 82.2 kips > 36.8 kips.
The vertical reinforcement in the pier at 1 percentThe vertical reinforcement in the pier at 1 percent
would require the would require the use of 4-#9 use of 4-#9 bars. bars. If the provisionsIf the provisions
of ACI-318-02 Section 10.8.4 and 15.8.2.1 are appli-of ACI-318-02 Section 10.8.4 and 15.8.2.1 are appli-
cable, 0.5 percent reinforcement ratio could be usedcable, 0.5 percent reinforcement ratio could be used
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 3737
2 2 22445 5 66..225 5 ..t t t t vv f  f F F f  f  ≤ ≤ φ φ = = φ φ −−
( ) ( )( ) ( )11..66 2233 69.869.8
9.26 9.26 ksi; ksi; 17.56 17.56 ksiksi
44((00..999944)) 44((00..999944))
vv t t  f  f f  f  = = = = = = ==
( ( ))2222
0.0.75 45 75 45 6.6.25 25 9.9.2626t t  F  F φ φ = = −−
1.51.5
11
11
1010.4.4 11.1.12255 00.0.0004 4 2299.0 .0 kkipipss
with with 12 12 in.in.
bbV V cc
cc
φ φ = = ==
−−
66
7.57.5
00..77 00..33 00..8822
1.5(12.5)1.5(12.5)
    
ψ ψ = = + + ==        
( ( ))66 22
2200 11..55 1122
2299..00 00..8822 1133..221 1 kkiippss
44..55 1122
vv
ccbbgg bb
vovo
 A A
V V V V 
 A A
× × ××
∴∴φ φ = = φ ψ φ ψ = = ==
22
// 22
22
c c ww
cc
 f  f b b d d 
V V 
′′
φ φ = φ= φ
( ( ))( ( ))
00..8855 22 00..000044
2200 1177..55 1188..882 2 kkiippss
22
× × == < 1.6(23)< 1.6(23)
2 2 //c c w w v v yy f  f b b d d A A f f d d ss  φ φ ++′′  
( ( ))0.80.85 2 5 2 0.00.004(20)(04(20)(17.17.5) 5) 0.20.2(2)(6(2)(60)(0)(17.517.5)) //88++
20 Inch Square20 Inch Square
Concrete Pier Concrete Pier 
(f' (f' = = 4000 psi)4000 psi)cc
V = 23kV = 23k
(Due To WL)(Due To WL)
P P = = 56k56k
(Due To WL)(Due To WL)
UPLIFTUPLIFT
P = 22kP = 22k
DLDL
Shear Lug GroutedShear Lug Grouted
Into Keyway In Pier Into Keyway In Pier 
 Anchor  Anchor 
RodRod
2 Inch2 Inch
GroutGrout
BedBed
 Fig. 9.4.6  Fig. 9.4.6 Example 9.4.3Example 9.4.3
    
which would permit use of 4-#7 bars.which would permit use of 4-#7 bars. T T uu = 1.6(56)= 1.6(56) − −
0.9(22) = 69.8 kips which produces 17.5 kips per bar.0.9(22) = 69.8 kips which produces 17.5 kips per bar.
AA single Grsingle Grade 60 #9 baade 60 #9 bar has ar has a φφ N  N nn = 0.9(60)(1.0) == 0.9(60)(1.0) =
54.0 kips. 54.0 kips. The vertical rebar The vertical rebar selected is a fuselected is a function of nction of 
the pier height due to the tension from momentthe pier height due to the tension from moment
requirements at the base of the pier in addition to therequirements at the base of the pier in addition to the
uplift tension. uplift tension. Since there is a Since there is a significant shear in significant shear in thisthis
example, it may be prudent to place hooks at the top of example, it may be prudent to place hooks at the top of 
the vertical reinforcing bars as illustrated in Figure 9.1.4.the vertical reinforcing bars as illustrated in Figure 9.1.4.
EXAMPLE 9.4.3:EXAMPLE 9.4.3:
Design Design forfor ShearShear Lugs Lugs (Pinne(Pinned Basd Base)e)
Design a shear lug detail for theDesign a shear lug detail for the WW1010××45 column consid-45 column consid-
ered in ered in Example 9.4.2. Example 9.4.2. See Figure See Figure 9.4.6.9.4.6.
The anchor rods in this example will be designed only toThe anchor rods in this example will be designed only to
transfer the net uplift from the column to the pier and thetransfer the net uplift from the column to the pier and the
shear lug will be designed to transfer the entire shear loadshear lug will be designed to transfer the entire shear load
to the pier with the confinement component being ignored.to the pier with the confinement component being ignored.
The design for the anchor rods will be identical to that inThe design for the anchor rods will be identical to that in
Example 9.4.1 whereExample 9.4.1 where 77//88 in. diameter anchor rods werein. diameter anchor rods were
selected. selected. Therefore, calculations for the anchor Therefore, calculations for the anchor rods are notrods are not
included in this exaincluded in this example. mple. As shown, the anAs shown, the anchor rods achor rods arere
 positioned  positioned outside outside the the column column flanges flanges to to prevent prevent interfer-interfer-
ence with the lug detail.ence with the lug detail.
 Procedur Procedure:e:
1.1. DeteDetermirmine tne the rhe requequireired emd embedbedmenment fot for thr the lue lug ing into tto thehe
concrete pier.concrete pier.
2.2. DeteDetermirmine ne the the appappropropriariate tte thickhicknesness fs for or the the luglug..
3.3. Size Size the the welwelds bds betwetween een the the lug lug and and the the basbase ple plateate..
Solution:Solution:
1.1. TTwo cwo critriterieria ara are use used ted to deo detertermine mine the the appappropropriariatete
embedment for the embedment for the lug. lug. These criteria are These criteria are the bearingthe bearing
strength of the concrete and the shear strength of thestrength of the concrete and the shear strength of the
concrete in front oconcrete in front of the lug. f the lug. As discussed in SeAs discussed in Sectionction
9.3, the shear strength of the concrete in front of the9.3, the shear strength of the concrete in front of the
lug is evaluated (in ultimate strength terms) as a uni-lug is evaluated (in ultimate strength terms) as a uni-
form form tensile tensile stress stress of of withwith φφ = 0.75 acting on= 0.75 acting on
an effective stress area defined by projecting a 45°an effective stress area defined by projecting a 45°
 plane from the bea plane from the bearing edge of the ring edge of the shear lug to the shear lug to the freefree
surface (the face surface (the face of the pier). of the pier). The bearing area of The bearing area of thethe
lug is to be excluded lug is to be excluded from the projected arfrom the projected area. ea. BecauseBecause
this criterion is expressed in ultimate strength terms,this criterion is expressed in ultimate strength terms,
the bearing strength of the concrete is also evaluatedthe bearing strength of the concrete is also evaluated
with awith an n ultimate sultimate strength trength approach. approach. The The ultimateultimate
 bearing strength of the c bearing strength of the concrete in contact with the lugoncrete in contact with the lug
is evaluated as 0.8is evaluated as 0.8 f  f ′′cc A A   as discussed in Section 9.3.as discussed in Section 9.3.
Because the anchor rods were sized for just theBecause the anchor rods were sized for just the
required uplift tension the 1.2(required uplift tension the 1.2( N  N  y y − − P  P aa) term addressed) term addressed
in Section 9.3 will be small and thus is being ignoredin Section 9.3 will be small and thus is being ignored
in this example.in this example.
The factored shear load = (1.6)(23) = 36.8 kips.The factored shear load = (1.6)(23) = 36.8 kips.
Equating this load to the bearing capacity of the con-Equating this load to the bearing capacity of the con-
crete, the following relationship is obtained:crete, the following relationship is obtained:
(0.8)(4000)((0.8)(4000)( A A))req’d.req’d. = 36,800= 36,800
(( A A)) req’d.req’d. = 11.5 in.= 11.5 in.22
Assuming the base plate and shear lug width to be 9Assuming the base plate and shear lug width to be 9
in., the required embedded depth (in., the required embedded depth (d d ) of the lug (in the) of the lug (in the
concrete) is calculated as:concrete) is calculated as:
d d = = 115/9 115/9 = = 1.28 1.28 in. in. UseUse 1½ 1½ in.in.
See Figure 9.4.7.See Figure 9.4.7.
3838 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
44 cc f   f  φφ    ′′
    
dd
G = GroutG = Grout
ThicknessThickness
 Fig. 9.4.7  Fig. 9.4.7 Shear Lug DepthShear Lug Depth Fig. 9.4.8 Fig. 9.4.8 Lug Failure PlaneLug Failure Plane
 2 2
 0 0 " "
 9 9 " "
 " " a a " "
 " " a a " "
   2  2  0  0  "  "  
9  9  ..5  5  "  "  
bb
11
11
11
11
Shear LugShear Lug
Shaded Area RepresentsShaded Area Represents
Failure PlaneFailure Plane
1 1/2"1 1/2"
    
Using this embedment, the shear strength of the con-Using this embedment, the shear strength of the con-
crete in front of the lug is crete in front of the lug is checked. checked. The projected areaThe projected area
of the failure plane at the face of the pier is shown inof the failure plane at the face of the pier is shown in
Figure 9.4.8.Figure 9.4.8.
Assuming the lug is positioned in the middle of theAssuming the lug is positioned in the middle of the
 pier and the  pier and the lug is 1 lug is 1 in. thick,in. thick,
aa == 5.5.5 i5 in. n. in in 20 20 inin. w. widide pe pieierr
bb == 1.1.5 i5 in. n. + 9+ 9.5 .5 inin. = . = 111.1.0 i0 in.n.
The projected area of this plane (Av), excluding theThe projected area of this plane (Av), excluding the
area of the lug, is then calculated as:area of the lug, is then calculated as:
 A Avv == ((2200))((1111..00)) −−1.5(9) = 207 in.1.5(9) = 207 in.22
Using this area, the shear capacity of the concrete inUsing this area, the shear capacity of the concrete in
front of the lug (front of the lug (V V uu) is calculated as:) is calculated as:
V V uu ==
==
== 3939.2 .2 kikips ps > > 3636.8 .8 kkipipss. . o.o.k.k.
With a shear lug, the concrete is capable of resistingWith a shear lug, the concrete is capable of resisting
the shear, as compared to Example 9.4.2, where thethe shear, as compared to Example 9.4.2, where the
anchor rods needed to have their shear transferred toanchor rods needed to have their shear transferred to
the top-of-pier tie reinforcement.the top-of-pier tie reinforcement.
2.2. UsinUsing wog workirking lng loadoads as and a nd a cancantiletilever ver modmodel fel for tor thehe
lug,lug,
 M  M  == V V ((GG++d d /2)/2)
== 2323(2(2+1+1.5.5/2/2) = 6) = 63.3.3 ki3 kip inp in..
 Note: Note: GG = 2 in. = thickness of grout bed.= 2 in. = thickness of grout bed.
For A36 steelFor A36 steel
 F  F bb == 00..7755((3366) ) = = 227 7 kkssii
 M  M  == 2277((99t t 22/6) = 40.5/6) = 40.5t t 22
Req’dReq’d t t = 1.25 in.= 1.25 in.
Use a Use a 1¼ in. thick 1¼ in. thick lug lug (( F  F  y y = 36 ksi)= 36 ksi)
Based on the discussion in Section 9.3 it is recom-Based on the discussion in Section 9.3 it is recom-
mended to use base plate of 1¼ in. minimum thick-mended to use base plate of 1¼ in. minimum thick-
ness with this shear lug.ness with this shear lug.
3.3. MosMost stt steel eel fabfabricricatoators wrs woulould rad rathether usr use hee heavy avy fillfilletet
welds than partial or full penetration welds to attachwelds than partial or full penetration welds to attach
the lug to the base plate. the lug to the base plate. The forces on the The forces on the welds arewelds are
as shown in Figure 9.4.9.as shown in Figure 9.4.9.
ConsiderConsider 55//1616 in. fillet welds,in. fillet welds,
 s s == 1.25 + 0.31.25 + 0.3125(1125(1/3)(2) /3)(2) = 1.46 in.= 1.46 in.
The resultant weld load (The resultant weld load ( f  f r r ) is calculated as:) is calculated as:
For aFor a 55//1616 in. fillet weld using E70 electrode, the allow-in. fillet weld using E70 electrode, the allow-
able loadable load (f (f allowallow..) is calculated as:) is calculated as:
 f  f allow.allow. == 00.3.312125(5(0.0.70707)7)(2(21)1)
== 4.4.64 k64 kipips/s/inin. < 4.. < 4.99 k99 kipips/s/inin..
UseUse 33//88 in. fillet weldsin. fillet welds
99..55 PPaarrttiiaal Bl Baasse Fe Fiixxiittyy
In some cases the designer may want to consider designingIn some cases the designer may want to consider designing
a column base that is neither pinned nor fixed. These maya column base that is neither pinned nor fixed. These may
 be cases  be cases where full where full fixity cannot fixity cannot be obtained, be obtained, or where tor where thehe
designer wants to know the designer wants to know the effect of partial fixity. The treat-effect of partial fixity. The treat-
ment of partial fixity is beyond the scope of this designment of partial fixity is beyond the scope of this design
guide; however, an excellent treatment of partial fixity canguide; however, an excellent treatment of partial fixity can
 be  be found found in in the the paper,paper, Stiffness Design of Column BasesStiffness Design of Column Bases
(Wald, 1998).(Wald, 1998).
10. SERVICEAB10. SERVICEABILITYILITY CRITERCRITERIAIA
The design of the lateral load envelope (in other words, theThe design of the lateral load envelope (in other words, the
roof bracing and wall support system) must provide for theroof bracing and wall support system) must provide for the
code-imposed loads, which establish the required strengthcode-imposed loads, which establish the required strength
of the of the structure. structure. AA second second category category of cof criteria establishesriteria establishes
the serviceability limits of the design. These limits arethe serviceability limits of the design. These limits are
rarely codified and are often selectively applied project byrarely codified and are often selectively applied project by
 project based on t project based on the experience of the he experience of the parties involved.parties involved.
In AISC Design Guide 3 (Fisher, 2003) several criteriaIn AISC Design Guide 3 (Fisher, 2003) several criteria
are given for the control of building drift and wall deflec-are given for the control of building drift and wall deflec-
tion. tion. These criteria, when These criteria, when used, should be used, should be presented to presented to thethe
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 3939
 Fig. 9.4.9  Fig. 9.4.9 Forces on Shear Lug WForces on Shear Lug Weldselds
44 c c vv f  f AAφφ    ′′
4(04(0.75.75) ) 4004000(207)0(207) /100/10000
f f vvvvf f 
ss
ccf f ccf f 
( ( ))
22    22
4.4.82 82 ((1.1.2828) ) 4.4.99 99 kikipsps/i/in.n.r r  f   f     = = + + ==
( ( ))( ( ))
( )( )( )( )
63.363.3
4.82 kips/in.4.82 kips/in.
11..4466 99
2323
1.28 kips/in.1.28 kips/in.
99 22
cc
vv
 f   f  
 f   f  
= = ==
= = ==
    
 building  building owner owner as as they they help help establish establish the the quality quality of of thethe
completed building.completed building.
To be useful, a serviceability criterion must set forthTo be useful, a serviceability criterion must set forth
three items:three items:
a. loading,a. loading,
 b. performance limit,  b. performance limit, andand
c. an analysis approach.c. an analysis approach.
Concerning lateral forces, the loading recommended byConcerning lateral forces, the loading recommended by
Design Guide 3 is the pressure due to wind speeds associ-Design Guide 3 is the pressure due to wind speeds associ-
ated with a 10-year recurreated with a 10-year recurrence interval. nce interval. These pressures areThese pressures are
approximately 75 percent of the pressures for strengthapproximately 75 percent of the pressures for strength
design criteria, based on a 50-year return period. The estab-design criteria, based on a 50-year return period. The estab-
lishment of deflection limits is explained below, with crite-lishment of deflection limits is explained below, with crite-
ria given for each of the wall types previously presented.ria given for each of the wall types previously presented.
The author recommends that frame drift be calculated usingThe author recommends that framedrift be calculated using
the bare the bare steel frame steel frame only. only. Likewise the Likewise the calculations for calculations for 
deflection of girts would be made using the bare steel sec-deflection of girts would be made using the bare steel sec-
tion. The contribution of non-structural components actingtion. The contribution of non-structural components acting
compositely with the structure to limit deflection is oftencompositely with the structure to limit deflection is often
difficult to quantify. Thus the direct approach (neglectingdifficult to quantify. Thus the direct approach (neglectingnon-structural contribution) is recommended and the loadsnon-structural contribution) is recommended and the loads
and limits are calibrated to this analysis approach. Theand limits are calibrated to this analysis approach. The
deflection limits for the various roof and wall systems aredeflection limits for the various roof and wall systems are
as follows.as follows.
1010.1.1 SeServrviciceaeabilbilitity y CrCrititereria ia foforr RoRoof of DeDesisigngn
In addition to meeting strength criteria in the design of theIn addition to meeting strength criteria in the design of the
roof structure, it is also necessary to provide for the proper roof structure, it is also necessary to provide for the proper 
 performance of  performance of elements and elements and systems attached systems attached to to the roof,the roof,
such as roofing, ceilings, hanging equipment, etc. Thissuch as roofing, ceilings, hanging equipment, etc. This
requires the control of deflections in the roof structure. requires the control of deflections in the roof structure. VVar-ar-
ious criteria have been published by various organizations.ious criteria have been published by various organizations.
These limits are:These limits are:
1.1. AmeAmericrican an InsInstitutitute ote of Sf Steeteel Col Constnstrucructiotion (An (AISCISC,,
1989):1989):
a.a. Depth of Depth of fully sfully stresstressed rooed roof purlinf purlins shouls should not bed not be
less than approximately span/20.less than approximately span/20.
2.2. StSteeeel Dl Dececk Ik Insnstittitutute (e (SDSDI, I, 20200000):):
a.a. MaximuMaximum deflem deflection oction of deck f deck due to udue to uniforniformly dis-mly dis-
tributed live load: span over 240.tributed live load: span over 240.
 b. b. Maximum deflection Maximum deflection of deck of deck due to due to a 200-lb a 200-lb con-con-
centrated load at midspan on a one-foot section of centrated load at midspan on a one-foot section of 
deck: span over 240.deck: span over 240.
3.3. StSteeeel Jl Joisoist It Insnstittitutute (e (SJSJI, I, 20200202):):
a.a. MaximuMaximum deflem deflection oction of joistf joists supps supporting orting plasteplaster r 
ceiling due to design live load: span over 360.ceiling due to design live load: span over 360.
 b. b. Maximum Maximum deflection deflection of of joists joists supporting supporting ceilingsceilings
other than plaster ceilings due to design live load:other than plaster ceilings due to design live load:
span over 240.span over 240.
4.4. NatiNationaonal Rl Roofoofing ing ConContratractoctors rs AssAssociociatioation (n (NRCNRCAA
2001):2001):
a.a. MaximuMaximum deck dm deck defleceflection dution due to full ue to full uniform niform load:load:
span over 240.span over 240.
 b. b. Maximum Maximum deck deck deflection deflection due due to to 300-lb 300-lb load load atat
midspan: span over 240.midspan: span over 240.
c.c. MaximuMaximum roof m roof strucstructure deture deflectflection due ion due to totalto total
load: span over 240.load: span over 240.
5.5. FaFactctorory My Mututuaual (l (FMFM, 2, 200000)0)::
a.a. MaximuMaximum deck dm deck defleceflection due tion due to a 300to a 300-lb con-lb concen-cen-
trated load at midspan: span over 200.trated load at midspan: span over 200.
AISC Design Guide 3 also presents deflection limits for AISC Design Guide 3 also presents deflection limits for 
 purlins  purlins supporting supporting structural structural steel steel roofs (both roofs (both through through fas-fas-
tener types and standing seam types). First, a limitingtener types and standing seam types). First, a limiting
deflection of span over 150 for snow loading is recom-deflection of span over 150 for snow loading is recom-
mended. mended. SecondlySecondly, attention is drawn , attention is drawn to conditions whereto conditions where
a flexible purlin parallels nonyielding construction such asa flexible purlin parallels nonyielding construction such as
at the building eave. at the building eave. In this case In this case deflection should be cdeflection should be con-on-
trolled to maintain positive rootrolled to maintain positive roof drainage. f drainage. The appropriateThe appropriate
design load is suggested as dead load plus 50 percent of design load is suggested as dead load plus 50 percent of 
snow load or dead load plus 5 psf live load to check for pos-snow load or dead load plus 5 psf live load to check for pos-
itive drainage under load.itive drainage under load.
Mechanical equipment, hanging conveyors, and other Mechanical equipment, hanging conveyors, and other 
roof supported equipment has been found to perform ade-roof supported equipment has been found to perform ade-
quately on roofs designed with deflection limits in the rangequately on roofs designed with deflection limits in the range
of span over 150 to span over 240 but these criteria shouldof span over 150 to span over 240 but these criteria should
 be  be verified verified with with the the equipment equipment manufacturer and manufacturer and buildingbuilding
owner. owner. Consideration should also Consideration should also be given to be given to differentialdifferential
deflections and localized loading conditions.deflections and localized loading conditions.
1100.2.2 MMeettaal Wl Waalll Pl Paanneelsls
Relative to serviceability metal wall panels have two desir-Relative to serviceability metal wall panels have two desir-
able attributes: 1) Their corrugated profiles make themable attributes: 1) Their corrugated profiles make them
fairly limber for out of fairly limber for out of plane distortions and 2) plane distortions and 2) their mate-their mate-
rial and fastening scheme are ductile (i.e., distortions andrial and fastening scheme are ductile (i.e., distortions and
 possible yielding do not produce  possible yielding do not produce fractures). fractures). Also, the mate-Also, the mate-
rial for edge and corner flashing and trim generally allowsrial for edge and corner flashing and trim generally allows
moment and distortion moment and distortion without failure. without failure. Because of Because of this thethis the
deflection limits associated with metal panel buildings aredeflection limits associated with metal panel buildings are
relatively generourelatively generous. s. They They are:are:
1.1. FraFrame deme defleflectiction (on (dridrift) pft) perperpendendicuicular tlar to the o the wall wall sursur--
face of frame: eave height divided by 60 to 100.face of frame: eave height divided by 60 to 100.
2.2. The The defdefleclection tion of of girgirts ats and nd winwind cd columolumns ns shoshould uld bebe
limited to span over 120, unless wall details and wall-limited to span over 120, unless wall details and wall-
supported equipment require stricter limits.supported equipment require stricter limits.
1010.3.3 PrPrececasast t WWaall ll PaPanenelsls
 Non-load bearing  Non-load bearing precast wall precast wall panels frequently span panels frequently span fromfrom
grade to eave as simple span membergrade to eave as simple span members. s. Therefore drift doesTherefore drift does
4040 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
,,
    
not change the not change the statics of the panstatics of the panel. el.The limitation on driftThe limitation on drift
in the building frame is established to control the amount of in the building frame is established to control the amount of 
movement in the joint at the base of the panel as the framemovement in the joint at the base of the panel as the frame
drifts. drifts. This limit has been pThis limit has been proposed to be roposed to be eave height over eave height over 
100. 100. AA special case special case exists when exists when precast panels precast panels are set are set atopatop
the perimeter the perimeter foundations to foundations to eliminate a grade eliminate a grade wall. wall. TheThe
foundation anchorage, the embedment of the panel in thefoundation anchorage, the embedment of the panel in the
soil and the potential of the floor slab to act as a fulcrumsoil and the potential of the floor slab to act as a fulcrum
mean that the frame deflections must be analyzed for com-mean that the frame deflections must be analyzed for com-
 patibility wit patibility with the panel h the panel design. It idesign. It is possible to s possible to tune frametune frame
drift with panel stresses but this requires interactiondrift with panel stresses but this requires interaction
 between  between frame frame designer designer and and panel panel designer. designer. Usually Usually thethe
design of the frame predesign of the frame precedes that of the panel. cedes that of the panel. In this caseIn this case
the frame behavior and panel design criteria should be care-the frame behavior and panel design criteria should be care-
fully specified in the construction documents.fully specified in the construction documents.
1100..44 MMaassoonnrry Wy Waallllss
Masonry walls may be hollow, grouted, solid, or groutedMasonry walls may be hollow, grouted, solid, or grouted
and and reinforced. reinforced. Masonry Masonry itself is itself is a ba brittle, non-ductilerittle, non-ductile
material. material. Masonry Masonry with steel with steel reinforcement reinforcement has has ductileductile
 behavior overall  behavior overall but but will will show show evidence of evidence of cracking whencracking when
subjected to loads which stress the masonry in tension.subjected to loads which stress the masonry in tension.When masonry is attached to a When masonry is attached to a supporting steel framework,supporting steel framework,
deflection of the supports may induce stresses in thedeflection of the supports may induce stresses in the
masonrymasonry. . It is rarely It is rarely feasible to provide feasible to provide sufficient steelsufficient steel
(stiffness) to keep the masonry stresses below cracking lev-(stiffness) to keep the masonry stresses below cracking lev-
els, thus flexural tension cracking in the masonry is likelyels, thus flexural tension cracking in the masonry is likely
and when properly detailed is not considered a detriment.and when properly detailed is not considered a detriment.
The correct strategy is to impose reasonable limits on theThe correct strategy is to impose reasonable limits on the
support movements and detail the masonry to minimize thesupport movements and detail the masonry to minimize the
impact of cracking.impact of cracking.
Masonry should be provided with vertical control jointsMasonry should be provided with vertical control joints
at the building at the building columns and wind columns and wind columns. columns. This preventsThis prevents
flexural stresses on the exterior face of the wall at theseflexural stresses on the exterior face of the wall at these
locations from inward wind. locations from inward wind. Because the top of Because the top of the wall isthe wall is
generally free to rotate, no special provisions are requiredgenerally free to rotate, no special provisions are required
there. there. The base of the The base of the wall joint is most difficult to address.wall joint is most difficult to address.
To carry the weight of the wall the base joint must be solid,To carry the weight of the wall the base joint must be solid,
not caulked. not caulked. Likewise, the mortar Likewise, the mortar in the joints in the joints make themake the
 base of the  base of the wall a fixed wall a fixed condition until condition until the wall cracks.the wall cracks.
Frame drift recommendations are set to limit the size of Frame drift recommendations are set to limit the size of 
the inevitable crack at the inevitable crack at the base of the base of the wall. the wall. Because rein-Because rein-
forced walls can spread the horizontal base cracks over sev-forced walls can spread the horizontal base cracks over sev-
eral joints, separate creral joints, separate criteria are given fiteria are given for them. or them. If proper If proper 
 base joints are provided, reinforce base joints are provided, reinforced walls can be consideredd walls can be considered
as having the behavior of precast walls; in as having the behavior of precast walls; in other words, sim-other words, sim-
 ple span element ple span elements with s with pinned bases. pinned bases. In that In that case the limcase the limitit
for precast for precast wall panels would wall panels would be applicable. be applicable. Where wain-Where wain-
scot walls are used, consideration must be given to the jointscot walls are used, consideration must be given to the joint
 between metal wall panel and masonry wainscot.  between metal wall panel and masonry wainscot. The rela-The rela-
tive movements of the two systems in response to windtive movements of the two systems in response to wind
must be controlled to maintain the integrity of the jointmust be controlled to maintain the integrity of the joint
 between the two  between the two materials.materials.
The recommended limits for the deflection of elementsThe recommended limits for the deflection of elements
supporting masonry are:supporting masonry are:
1.1. FraFrame deme defleflectioction (dn (drifrift) pet) perperpendindiculcular tar to an uo an unrenrein-in-forced wall should allow no more than aforced wall should allow no more than a 11//1616 in. crack in. crack 
to open in one joint at the base to open in one joint at the base of the wall. of the wall. The driftThe drift
allowed by this criterion can be conservatively calcu-allowed by this criterion can be conservatively calcu-
lated by relating the wall thickness to the eave heightlated by relating the wall thickness to the eave height
and taking the crack width at the wall face asand taking the crack width at the wall face as 11//1616 in.in.
and zero at the opposite face.and zero at the opposite face.
2.2. FraFrame deme defleflectioction (dn (drifrift) pt) perperpendendicuicular lar to a rto a reineinforforcedced
wall is recommended to be eave height over 100.wall is recommended to be eave height over 100.
3.3. The The defdefleclection tion of of wind wind colcolumnumns as and nd girgirts sts shouhould bld bee
limited to span over 240 but not greater than 1.5 in.limited to span over 240 but not greater than 1.5 in.
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 4141
,,
    
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS—ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION // 4343
11. INTRODUCTION11. INTRODUCTION
This section of the guide deals with crane buildings, andThis section of the guide deals with crane buildings, and
will include coverage of those aspects of industrial build-will include coverage of those aspects of industrial build-
ings peculiar to the existence of overhead and underhungings peculiar to the existence of overhead and underhung
cranes. cranes. In that context, the major difIn that context, the major difference between craneference between crane
 buildings and other industrial buildings is the  buildings and other industrial buildings is the frequency offrequency of 
loading caused by the cranes. loading caused by the cranes. Thus, crane buildings shouThus, crane buildings shouldld
 be classif be classified for ied for design purposes design purposes according to according to the frequencythe frequency
of loading.of loading.
Crane building classifications have been established inCrane building classifications have been established in
the AISE Technical Report No. 13 (AISE, 2003) as classesthe AISE Technical Report No. 13 (AISE, 2003) as classes
A, B, C and D. A, B, C and D. ClassificatioClassifications for cranes have been estab-ns for cranes have been estab-
lished by the lished by the Crane Manufacturers AssociatiCrane Manufacturers Association of Americaon of America
(CMAA, 2002). (CMAA, 2002). These designations sThese designations should not be confusedhould not be confused
with the building designations.with the building designations.
111.11.1 AISE AISE TTechnicechnical Repal Report ort 13 Bu13 Building ilding ClassClassifica-ifica-
tionstions
Class AClass A are those buildings in which members may experi-are those buildings in which members may experi-
ence either 500,000 to 2,000,000 repetitions or over ence either 500,000 to 2,000,000 repetitions or over 
2,000,000 repetitions in the estimated life span of the 2,000,000 repetitions in the estimated life span of the build-build-
ing of approximately 50 years. The ing of approximately 50 years. The owner must analyze theowner must analyze the
service and determinservice and determine which load condition may ape which load condition may apply. ply. ItIt
is recommended that the following building types be con-is recommended that the following building types be con-
sidered as Class A:sidered as Class A:
Batch annealing buildingsBatch annealing buildings
Scrap yardsScrap yards
Billet yardsBillet yards
Skull breakersSkull breakers
Continuous casting buildingsContinuous casting buildings
Slab yardsSlab yards
FoundriesFoundries
Soaking pit buildingsSoaking pit buildings
Mixer buildingMixer building
Steelmaking buildingsSteelmaking buildings
Mold conditioning buildingsMold conditioning buildings
Stripper buildingsStripper buildings
Scarfing yardsScarfing yards
Other buildings as based on predicted operationalOther buildings as based on predicted operational
requirementsrequirements
Class BClass B are those buildings in which members may expe-are those buildings in which members may expe-
rience a repetition from 100,000 to 500,000 cycles of a spe-rience a repetition from 100,000 to 500,000 cycles of a spe-
cific loading, or 5 to 25 repetitions of such load per day for cific loading, or 5 to 25 repetitions of such load per day for a life of approximately 50 years.a life of approximately 50 years.
Class C Class C are those buildings in which are those buildings in which members may expe-members may expe-
rience a repetition of from 20,000 to 100,000 cycles of arience a repetition of from 20,000 to 100,000 cycles of a
specific loading during the expected life of a specific loading during the expected life of a structure, or 1structure, or 1
to 5 repetitions of such load per day for a life of approxi-to 5 repetitions of such load per day for a life of approxi-
mately 50 years.mately 50 years.
Class DClass D are those buildings in which no member willare those buildings in which no member will
experience more than 20,000 repetitions of a specific load-experience more than 20,000 repetitions of a specific load-
ing during the expected life of ing during the expected life of a structure.a structure.
111.1.22 CMCMAAAA 70 C70 Crarane Cne Clalassssifificaicatitiononss
The following classifications are taken directly fromThe following classifications are taken directly from
CMACMAAA 70.70.
“10-2 CRANE CLASSIFICATIONS“10-2 CRANE CLASSIFICATIONS
2.12.1 ServService clice classes asses have behave been esten establisablished so thed so that the hat the mostmost
economical crane for the installation may be specifiedeconomical crane for the installation may be specified
in accordance with this in accordance with this specification.specification.
The crane service classification is based on the loadThe crane service classification is based on the load
spectrum reflecting the actual service conditions asspectrum reflecting the actual service conditions as
closely as possible.closely as possible.
Load spectrum is a Load spectrum is a mean effective load, which is uni-mean effective load, which is uni-
formly distributed over a probability scale and formly distributed over a probability scale and appliedapplied
to the equipment at a specified frequto the equipment at a specified frequency. ency. The selec-The selec-
tion of the properly sized crane component to performtion of the properly sized crane component to perform
a given function is determined by the varying loada given function is determined by the varying load
magnitudes and given load cycles which can bemagnitudes and given load cycles which can be
expressed in terms of expressed in terms of the mean effective load factor.the mean effective load factor.
wherewhere
W W == Load Load magnimagnitude; tude; expreexpressed assed as a rats a ratio of io of eacheach
lifted load to the ratelifted load to the rated capacityd capacity. . Operation withOperation with
no lifted load and the weight of any attachmentno lifted load and the weight of any attachment
must be included.must be included.
 P  P  == Load Load probaprobabilibility; exty; expresspressed as a ed as a ratiratio of cyco of cyclesles
under each load magnitude condition to the totalunder each load magnitude condition to the total
cycles. cycles. The sum total of the load prThe sum total of the load probabilitiesobabilities P  P 
must equal 1.0.must equal 1.0.
Part 2Part 2
INDUSTRIAL BUILDINGS—GENERALINDUSTRIAL BUILDINGS—GENERAL
3 3 3 3 3 3 3333
1 1 1 1 2 2 2 2 33    n n nn K  K W W P P W W P P W W W W P P = = + + + + ++
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS ROOFS ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 4343
    
4444 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS—ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
 K  K  == Mean efMean effectfective loaive load factod factor. (r. (Used to eUsed to estabstablishlish
crane service class only.)crane service class only.)
All classes of cranes are affected by All classes of cranes are affected by the operating condi-the operating condi-
tions, therefore, for the purpose of the classifications it istions, therefore, for the purpose of the classifications it is
assumed that the crane will be operating in assumed that the crane will be operating in normal ambientnormal ambient
temperature of 0 °F to 104 °F (-17.7 °C to 40 °C) and nor-temperature of 0 °F to 104 °F (-17.7 °C to 40 °C) and nor-
mal atmospheric conditions (free from excessive dust,mal atmospheric conditions (free from excessive dust,moisture and corrosive fumes).moisture and corrosive fumes).
The cranes can be classified into loading groups accord-The cranes can be classified into loading groups accord-
ing to the service conditions of the most severely loadeding to the service conditions of the most severely loaded
 part  part of of the the crane. crane. The The individual individual parts parts which which are are clearlyclearly
separate from the rest, or separate from the rest, or forming a self contained structuralforming a self contained structural
unit, can be classified into different loading groups if theunit, can be classified into different loading groups if the
service conditions are fully known.service conditions are fully known.
2.2.22 CCLALASSS S AA (S(STTANANDDBYBY OOR R ININFFRREEQUQUEENTNT SSEER-R-
VICE) This service class covers cranes which may beVICE) This service class covers cranes which may be
used in installations such as powerhouses, public util-used in installationssuch as powerhouses, public util-
ities, turbine rooms, motor rooms and transformer sta-ities, turbine rooms, motor rooms and transformer sta-
tions where precise handling of equipment at slowtions where precise handling of equipment at slow
speeds with long, idle period between lifts arespeeds with long, idle period between lifts are
required. required. Capacity loads Capacity loads may be handled may be handled for initialfor initial
installation of equipment and for infrequent mainte-installation of equipment and for infrequent mainte-
nance.nance.
2.32.3 CLACLASS B (SS B (LILIGHTGHT SESERRVICVICE) TE) This shis servervice cice coveoversrs
cranes which may be used in cranes which may be used in repair shops, light assem-repair shops, light assem-
 bly  bly operations, operations, service service buildings, buildings, light light warehousing,warehousing,
etc., where service requirements are light and theetc., where service requirements are light and the
speed is slowspeed is slow. . Loads may vary from Loads may vary from no load to occa-no load to occa-
sional full rated loads with two to five lifts per hour,sional full rated loads with two to five lifts per hour,
averaging 10 ft per lift.averaging 10 ft per lift.
2.42.4 CLASCLASS S C C (MOD(MODERAERATE TE SERSERVICEVICE) ) This This serviservicece
covers cranes that may be used in machine shops or covers cranes that may be used in machine shops or 
 paper mill  paper mill machine roomsmachine rooms, etc., , etc., where serviwhere service require-ce require-
ments are moderatments are moderate. e. In this type of In this type of service the craneservice the crane
will handle loads which average 50 percent of thewill handle loads which average 50 percent of the
rated capacity with 5 to rated capacity with 5 to 10 lifts per hour, averaging 1510 lifts per hour, averaging 15
ft, not more than 50 percent of the lift at rated capacity.ft, not more than 50 percent of the lift at rated capacity.
2.52.5 CLASCLASS S D D (HEA(HEAVYVY SERSERVICEVICE) ) This This serviservice ce covercoverss
cranes which may be used in heavy machine shops,cranes which may be used in heavy machine shops,
foundries, fabricating plants, steel warehouses, con-foundries, fabricating plants, steel warehouses, con-
tainer yards, lumber mills, etc., and standard dutytainer yards, lumber mills, etc., and standard duty
 bucket and  bucket and magnet operations where heavy magnet operations where heavy duty pro-duty pro-
duction is required. In this type of service, loadsduction is required. In this type of service, loads
approaching 50 percent of the rated capacity will beapproaching 50 percent of the rated capacity will behandled constanhandled constantly during tly during the working the working period. period. HighHigh
speeds are desirable for this type of service with 10 tospeeds are desirable for this type of service with 10 to
20 lifts per hour averaging 15 feet, not more than 6520 lifts per hour averaging 15 feet, not more than 65
 percent of the lifts at rated capacity percent of the lifts at rated capacity..
2.62.6 CLASCLASS E S E (SEV(SEVERE ERE SERSERVICEVICE) T) This his type type of sof servicervicee
requires a crane capable of handling loads approach-requires a crane capable of handling loads approach-
ing a rated capaciting a rated capacity throughout its ly throughout its life. ife. ApplicationsApplications
may include magnet/bucket combination cranes for may include magnet/bucket combination cranes for 
scrap yards, cement mills, lumber mills, fertilizer scrap yards, cement mills, lumber mills, fertilizer 
 plants, container  plants, container handling, etc., handling, etc., with 20 with 20 or more or more liftslifts
 per hour at or near the rated capacity. per hour at or near the rated capacity.
2.72.7 CLASCLASS S F F (CON(CONTINUTINUOUS OUS SEVSEVERE ERE SERSERVICEVICE))
This type of service requires a crane capable of han-This type of service requires a crane capable of han-dling loads approaching rated capacity continuouslydling loads approaching rated capacity continuously
under severe service conditions throughout its life.under severe service conditions throughout its life.
Applications may include custom designed specialtyApplications may include custom designed specialty
cranes essential to performing the critical work taskscranes essential to performing the critical work tasks
affecting the total production facility. These cranesaffecting the total production facility. These cranes
must provide the highest reliability with special atten-must provide the highest reliability with special atten-
tion to ease of maintenance features.”tion to ease of maintenance features.”
The class of crane, the type of crane, and loadings allThe class of crane, the type of crane, and loadings all
affect the design. affect the design. The fatigue associaThe fatigue associated with crane class isted with crane class is
especially critical for the design of crane runways and con-especially critical for the design of crane runways and con-
nections of crane runwnections of crane runway beams to columns. ay beams to columns. Classes E andClasses E and
F produce particularly sevF produce particularly severe fatigue conditions. ere fatigue conditions. The deter-The deter-
mination of fatigue stress levels and load conditions is dis-mination of fatigue stress levels and load conditions is dis-
cussed in more detail in the cussed in more detail in the next section.next section.
The CMAAThe CMAA 70 crane classifications do not re70 crane classifications do not relate directlylate directly
to the AISC loading conditions for to the AISC loading conditions for fatigue. Loading condi-fatigue. Loading condi-
Table 11.2.1 Table 11.2.1 Crane Loading Crane Loading ConditionsConditions
CMAA 70 CraneCMAA 70 Crane
ClassificationClassification
AISC LoadingAISC Loading
ConditionCondition
A, BA, B
C, DC, D
EE
FF
11
22
33
44
Table 11.2.Table 11.2.2 2 AISC LoadiAISC Loading Cyclesng Cycles
Loading Loading Condition Condition From From ToTo
1 20,0001 20,000
aa
  100,000  100,000
bb
  
2 2 100,000 100,000 500,000500,000
cc
  
3 3 500,000 500,000 2,000,0002,000,000
dd
  
44
OverOver
2,000,0002,000,000
aa
Approximately equivalent to two applications every day for Approximately equivalent to two applications every day for 25 years.25 years.
bb
Approximately equivalApproximately equivalent to 10 applications every day for ent to 10 applications every day for 25 years.25 years.
cc
ApproximateApproximately equivalent to 50 applications every day for ly equivalent to 50 applications every day for 25 years.25 years.
dd
Approximately equivaApproximately equivalent to 200 applications every day for lent to 200 applications every day for 25 years.25 years.  
4444 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS ROOFS ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
    
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS—ROOFS TO ANCHOR RODSTO ANCHOR RODS 2ND EDITION2ND EDITION // 4545
tion refers to the fatigue criteria given in Appendix K of thetion refers to the fatigue criteria given in Appendix K of the
AISC ASDAISC ASD SpecificationsSpecifications (AISC, 1989). Based on the aver-(AISC, 1989). Based on the aver-
age number of lifts for each CMAAage number of lifts for each CMAA 70 crane classification,70 crane classification,
the crane classes corresponding to the AISC ASD loadingthe crane classes corresponding to the AISC ASD loading
conditions are shown in Table 11.2.1.conditions are shown in Table 11.2.1.
The approximate number of loading cycles for The approximate number of loading cycles for each load-each load-
ing condition is given in the AISC ASD Specification Tableing condition is given in the AISC ASD Specification Table
A-K4.1. A-K4.1. The TThe Table is repeated below as Table is repeated below as Table 11.2.2.able 11.2.2.
The AISCThe AISCLRFD Specification LRFD Specification (AISC, 1999) no longer (AISC, 1999) no longer 
refers to loading conditions. Therefers to loading conditions. The LRFD Specification LRFD Specification usesuses
equations to determine an allowable stress range for a givenequations to determine an allowable stress range for a given
number of stress cycles. Thenumber of stress cycles. The LRFD  LRFD SpecificationSpecification states that,states that,
“The Engineer of Record shall provide either complete“The Engineer of Record shall provide either complete
details including weld sizes or shall specify the planneddetails including weld sizes or shall specify the planned
cycle life and the maximum range of moments, shears andcycle life and the maximum range of moments, shears and
reactions for the connections.” To use the reactions for the connections.” To use the LRFD equations,LRFD equations,
the designer must enter the value ofthe designer must enter the value of  N  N , which is the stress, which is the stress
range fluctuations in design life, into range fluctuations in design life, into the appropriate designthe appropriate design
equations provided in theequations provided in the SpecificationSpecification. . The The LRFD LRFD fatiguefatigue
 provisions are the most up to date AI provisions are the most up to date AISC provisions and areSC provisions and are
recommended for use by recommended for use by the author.the author.
12. FATIGUE12. FATIGUE
Proper functioning of the bridge cranes is dependent uponProper functioning of the bridge cranes is dependent upon
 proper crane  proper crane runway girder runway girder design and design and detailing. The run-detailing. The run-
way design must account for the fatigue effects caused byway design must account for the fatigue effects caused by
the repeated passing of the crane. Runway girders should the repeated passing of the crane. Runway girders should bebe
thought of as a part of a system comprised of the crane rails,thought of as a part of a system comprised of the crane rails,
rail attachments, electrification support, crane stops, cranerail attachments, electrification support, crane stops, crane
column attachment, tie back and the girder itself. All of column attachment, tie back and the girder itself. All of 
these items should be incorporated into the design andthese items should be incorporated into the design and
detailing of the crane runway girder system.detailing of the crane runway girder system.
Based on the author’s experience it is estimated that 90Based on the author’s experience it is estimated that 90
 percent  percent of of crane crane runway runway girder girder problems problems are are associatedassociated
with fatigue cracking.with fatigue cracking.
Engineers have designed crane runway girders that haveEngineers have designed crane runway girders that have
 performed with m performed with minimal problems winimal problems while being subjected thile being subjected too
millions of cycles of loadmillions of cycles of loading. ing. The girders that are perfoThe girders that are perform-rm-
ing successfully have been properly designed and detaileding successfully have been properly designed and detailed
to:to:
•• LimLimit it the the appapplielied sd stretress ss ranrange, ge, to to accaccepteptablable le leveevels.ls.
•• AAvoivoid ud unexnexpecpected ted resrestratraintints as at t the the attattachachmenments ts andand
supports.supports.
•• AAvoivoid sd stretress ss conconcencentratratiotions ns at at cricritictical al loclocatiationsons..
•• AAvoivoid ecd eccencentritricitcities ies due due to to rairail ml misaisaliglignmenment ont or cr cranranee
travel and other out-of plane distortions.travel and other out-of plane distortions.
•• MiMininimmizize re resesididuual al ststreressssees.s.
Even when all state of the art design provisions are fol-Even when all state of the art design provisions are fol-
lowed building owners can expect to perform periodiclowed building owners can expect to perform periodic
maintenance maintenance on runway on runway systems. systems. Runway Runway systems tsystems thathat
have performed well have been properly maintained byhave performed well have been properly maintained by
keeping the rails and girders aligned and keeping the rails and girders aligned and level.level.
Some fatigue damage should be anticipated eventuallySome fatigue damage should be anticipated eventually
even in “perfectly designed” structures since fabricationeven in “perfectly designed” structures since fabrication
and erection cannot be perfect. Fabricating, erecting, andand erection cannot be perfect. Fabricating, erecting, and
maintaining the tolerances required in the AISCmaintaining the tolerances required in the AISC Code of Code of 
Standard Practice for Steel Buildings and BridgesStandard Practice for Steel Buildings and Bridges (AISC,(AISC,
2000), the American Welding Society,2000), the American Welding Society, Structural Welding Structural Welding 
Code—Steel Code—Steel , AWS D1.1, (AWS 2002), and the AISE, AWS D1.1, (AWS 2002), and the AISE Tech-Tech-
nical Report 13, Guide for the Design and Construction of nical Report 13, Guide for the Design and Construction of 
 Mill Buil Mill Buildingsdings (AISE, 2003), should be followed in order to(AISE, 2003), should be followed in order to
 provide predicted fatigue behavior provide predicted fatigue behavior..
Fatigue provisions have a 95 percent reliability factor Fatigue provisions have a 95 percent reliability factor 
(two standard deviations below mean curve of test (two standard deviations below mean curve of test data) for data) for 
a given stress range, and expected lifa given stress range, and expected life condition. e condition. Thus, it isThus, it is
reasonable to expect that 5 percent of similar details canreasonable to expect that 5 percent of similar details can
experience fatigue failure before the expected fatigue life isexperience fatigue failure before the expected fatigue life is
expired. expired. HoweverHowever, if the designer , if the designer chooses a design lichooses a design life of fe of 
the structure to be shorter than the expected fatigue life per the structure to be shorter than the expected fatigue life per 
AISC criteria, the reliability of a critical detail should beAISC criteria, the reliability of a critical detail should be
higher than 95 percent.higher than 95 percent.
12.1 12.1 Fatigue Fatigue DamageDamage
Fatigue damage can be characterized as progressive crack Fatigue damage can be characterized as progressive crack 
growth due to flucgrowth due to fluctuating stress on ttuating stress on the memberhe member. . FatigueFatigue
cracks initiate at small defects or imperfections in the basecracks initiate at small defects or imperfections in the base
material or weld metal. The imperfections act as stress ris-material or weld metal. The imperfections act as stress ris-
ers that magnify the applied elastic stresses into smallers that magnify the applied elastic stresses into small
regions of plastic stress. As load cycles are applied, theregions of plastic stress. As load cycles are applied, the
 plastic strain in  plastic strain in the small the small plastic region plastic region advances until advances until thethe
material separates and the cracmaterial separates and the crack advances. k advances. At that point, theAt that point, the
 plastic stress region  plastic stress region moves to the moves to the new tip of new tip of the crack andthe crack and
the process repeats itself. Eventually, the crack sizethe process repeats itself. Eventually, the crack size
 becomes large  becomes large enough that the enough that the combined effecombined effect of the crack ct of the crack 
size and the applied stress exceed the toughness of thesize and the applied stress exceed the toughness of the
material and a final fracture occurs.material and a final fracture occurs.
Fatiguefailures result from repeated application of serv-Fatigue failures result from repeated application of serv-
ice loads, which cause crack initiation and propagation toice loads, which cause crack initiation and propagation to
final fracture. final fracture. The dominant varThe dominant variable is the tiable is the tensile stressensile stress
range imposed by the repeated application of the liverange imposed by the repeated application of the live
load—not the maximum stress that is imposed by live plusload—not the maximum stress that is imposed by live plus
dead load. dead load. Fatigue daFatigue damage develops mage develops in three in three stages. stages. TheseThese
are crack initiation, stable crack growth and unstable crack are crack initiation, stable crack growth and unstable crack 
growth to fracture. Of these the growth to fracture. Of these the crack initiation phase takescrack initiation phase takes
up about eighty percent of the total fatigue life; thus whenup about eighty percent of the total fatigue life; thus when
cracks are of detectible size the fatigue life cracks are of detectible size the fatigue life of a member or of a member or 
detail is virtually exhausted and prompt remedial actiondetail is virtually exhausted and prompt remedial action
should be taken. should be taken. Abrupt changes in cross sAbrupt changes in cross section, geomet-ection, geomet-
rical discontinuities such as toes of rical discontinuities such as toes of welds, unintentional dis-welds, unintentional dis-
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS ROOFS ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 4545
    
4646 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS—ROOFS TO ANCHOR RODSTO ANCHOR RODS 2ND EDITION2ND EDITION
 N  N  == NumbeNumber of str of stress rress range fange fluctluctuatiouations in dns in designesign
life,life,
== NumbeNumber of str of stress rress range fange fluctluctuatiouations per ns per dayday ××
365365 ×× years of design life.years of design life.
 F  F TH TH  == ThresThreshold fahold fatigutigue strese stress ranges range, maxi, maximum stmum stressress
range for indefinite design life.range for indefinite design life.
The standard fatigue design equation The standard fatigue design equation applies:applies:
 f  f  sr  sr  ≤ ≤ F  F SRSR
wherewhere
 f  f  sr  sr  == the the serviservice face fatigue tigue strestress rss range ange based based on ton thehe
cyclic load range, an analytical model, and thecyclic load range, an analytical model, and the
section properties of the particular member atsection properties of the particular member at
the fatigue sensitive detail location.the fatigue sensitive detail location.
The 1999 AISCThe 1999 AISC LRFD Specificati LRFD Specificationon, as well as previous, as well as previous
AISC specifications, limit the allowable stress range for aAISC specifications, limit the allowable stress range for a
given service life based on an anticipated severity of thegiven service life based on an anticipated severity of the
stress riser for a given fabricated condition.stress riser for a given fabricated condition.
Consideration of fatigue requires that the Consideration of fatigue requires that the designer deter-designer deter-
mine the anticipated number of full uniform amplitude loadmine the anticipated number of full uniform amplitude load
cycles. To properly apply the AISCcycles. To properly apply the AISC SpecificationSpecification (1999)(1999)
fatigue equations to crane runway girder fatigue analyses,fatigue equations to crane runway girder fatigue analyses,
one must understand the difference between the AISCone must understand the difference between the AISC
fatigue provisions determined using data from cyclic con-fatigue provisions determined using data from cyclic con-
stant amplitude loading tests, and crane runway variablestant amplitude loading tests, and crane runway variable
amplitude cyclic loaamplitude cyclic loadings. dings. It is a common practIt is a common practice for theice for the
crane runway girder to be designed for service life that iscrane runway girder to be designed for service life that is
consistent with the crane classification. The Crane Manu-consistent with the crane classification. The Crane Manu-
facturers Association of America,facturers Association of America, Specifications for Elec-Specifications for Elec-
tric Overhead Traveling Cranestric Overhead Traveling Cranes (CMAA, 2002) includes(CMAA, 2002) includes
crane designations that define the anticipated number of fullcrane designations that define the anticipated number of full
uniform amplitude load cycles for the life of the uniform amplitude load cycles for the life of the crane. Cor-crane. Cor-
relating the CMAArelating the CMAA 70 crane designations for a given crane70 crane designations for a given crane
to the required fatigue life for the structure cannot beto the required fatigue life for the structure cannot be
directly determined. The crane does not lift its maximumdirectly determined. The crane does not lift its maximumload, or travel at the same speed, every day or every hour.load, or travel at the same speed, every day or every hour.
continuities from lack of perfection in fabrication, effects of continuities from lack of perfection in fabrication, effects of 
corrosion and residual stresses all have a bearing on thecorrosion and residual stresses all have a bearing on the
localized range of tensile stress at details that lead to crack localized range of tensile stress at details that lead to crack 
initiation. These facts make it convenient and desirable toinitiation. These facts make it convenient and desirable to
structure fatigue design provisions on the basis of cate-structure fatigue design provisions on the basis of cate-
gories, which reflect the increase in tensile stress range duegories, which reflect the increase in tensile stress range due
to the severity of the discontinuities introduced by typicalto the severity of the discontinuities introduced by typical
details. Application of stress concentration factors todetails. Application of stress concentration factors to
stresses determined by usual analysis is not appropriate.stresses determined by usual analysis is not appropriate.
However, fluctuatHowever, fluctuating compressive stresses in ing compressive stresses in a region of a region of 
tensile residual stress may cause a net fluctuating tensiletensile residual stress may cause a net fluctuating tensile
stress or reversal of stress, which may cause cracks to initiate.stress or reversal of stress, which may cause cracks to initiate.
The 1999 AISCThe 1999 AISC LRFD Speci LRFD Specificationfication provides continuous provides continuous
functions in terms of cycles of functions in terms of cycles of life, and stress range, in lieulife, and stress range, in lieu
of the previous criteria for fatigue life that reflected theof the previous criteria for fatigue life that reflected the
database only at the break points in the step-wise format.database only at the break points in the step-wise format.
The 1999 AISC provisions use a single The 1999 AISC provisions use a single table that is dividedtable that is divided
into sections, which describe various conditions. The sec-into sections, which describe various conditions. The sec-
tions are:tions are:
1.1. PlPlaiain man mateteririal aal awaway fry from aom any wny weleldidingng..
2.2. ConConnecnected mted mateateriarial in mel in mechachanicnicallally fasy fastentened joed jointints.s.
3.3. WWeldelded jed joinoints jts joinioining cng compoomponentnents of s of builbuilt-ut-up mep membembers.rs.
4.4. LonLongitgitudiudinal nal filfillet let welwelded ded end end conconditditionions.s.
5.5. WWeldelded jed joinoints tts tranransvesverse rse to dito direcrectiotion of sn of stretress.ss.
6.6. BasBase mete metal at al at welweldedtded tranransvesverse mrse membember coer connennectictionsons..
7.7. BaBase se memetatal al at st shohort rt atattatachchmementnts.s.
88.. MMiisscceellllaanneeoouuss..
The 1999 AISC provisions use equations to calculate theThe 1999 AISC provisions use equations to calculate the
design stress range for a chosen design life,design stress range for a chosen design life,  N  N , for various, for various
conditions and stress categories. The point of potentialconditions and stress categories. The point of potential
crack initiation is identified by description, and shown incrack initiation is identified by description, and shown in
the table figures. The tables contain the threshold designthe table figures. The tables contain the threshold design
stress,stress,  F  F TH TH , for each stress category, and also provide the, for each stress category, and also provide the
detail constant,detail constant, C C  f  f , applicable to the stress category that is, applicable to the stress category that is
required for calculating the design stress range,required for calculating the design stress range,  F  F SRSR. For . For 
example, for the majority of example, for the majority of stress categories:stress categories:
wherewhere
 F  F SRSR == the Dethe Design Ssign Stress Rtress Range fange for a defior a defined loaned load con-d con-
dition (number of cycles) and a stress categorydition (number of cycles) and a stress category
of the fatigue sensitive detail.of the fatigue sensitive detail.C C  f  f  == ConsConstant frtant from Aom AISC ISC TTable able A-K3A-K3.1.1
0.3330.333
  
 f   f  
SSR R TTH  H  
C C 
 F  F F F 
 N  N 
  
= = ≥≥  
  
Table 12.1.1 CMAA 70 Table 12.1.1 CMAA 70 ClassificationClassification
v. Design Lifev. Design Life
CMAA 70 CraneCMAA 70 Crane
ClassificationClassification
Design LifeDesign Life
A 20,000A 20,000
B 50,000B 50,000
C 100,000C 100,000
D 500,000D 500,000
E 1,500,000E 1,500,000
F >2,000,000F >2,000,000
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DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS—ROOFS TO ANCHOR RODSTO ANCHOR RODS 2ND EDITION2ND EDITION // 4747
Shown in TablShown in Table 12.1.1 are e 12.1.1 are estimates of the number of estimates of the number of cyclescycles
of full uniform aof full uniform amplitude for CMAmplitude for CMAAA 70 crane classifica70 crane classifica--
tions tions AA through F over through F over a 40-year period. a 40-year period. It must be eIt must be empha-mpha-
sized that these are only guidelines and actual duty cyclessized that these are only guidelines and actual duty cycles
can only be established from the building’s owner and thecan only be established from the building’s owner and the
crane manufacturer.crane manufacturer.
12.12.22 CraCrane Rune Runwanway Faty Fatiguigue Cone Considesideratrationsions
The 1999 AISCThe 1999 AISC SpecificationSpecification provisions  provisions as as they they relate relate toto
crane runwcrane runway design ay design are discusseare discussed belowd below. . AA completecomplete
design example is provided in a paper design example is provided in a paper by Fisher and Vby Fisher and Van dean de
Pas titled, “New Fatigue Provisions for the Design of CranePas titled, “New Fatigue Provisions for the Design of Crane
Runway Girders,” (Fisher, 2002). The fatigue provisionsRunway Girders,” (Fisher, 2002). The fatigue provisions
discussed below assume that the girders are fabricateddiscussed below assume that the girders are fabricated
using the AWS provisions for cyclically loaded structures.using the AWS provisions for cyclically loaded structures.
In a few instances, additional weld requirements are recom-In a few instances, additional weld requirements are recom-
mended by AISEmended by AISE Technical Report 13Technical Report 13. These are pointed. These are pointed
out in the sections below.out in the sections below.
Tension Flange StressTension Flange Stress
When runway girders are fabricated from plate material,When runway girders are fabricated from plate material,
fatigue requirements are more severe than for rolled shapefatigue requirements are more severe than for rolled shape
girders. girders. The 1999 The 1999 AISCAISC SpecificationSpecification Appendix K3, TableAppendix K3, Table
A-K3.1, Section 3.1, applies to the design of the plate mate-A-K3.1, Section 3.1, applies to the design of the plate mate-
rial and Sectirial and Section 1.1 applies to plaion 1.1 applies to plain material. n material. Stress CStress Cate-ate-
gory B is required for plate girders as compared to stressgory B is required for plate girders as compared to stress
Category Category AA for rolled shapesfor rolled shapes..
Web to Flange WeldsWeb to Flange Welds
Appendix K3, Table A-K3.1, Section 8.2 of the 1999 AISCAppendix K3, Table A-K3.1, Section 8.2 of the 1999 AISC
SpecificationSpecification controls the shear in fillet welds, which con-controls the shear in fillet welds, which con-
nect the web to the tension and the compression flanges,nect the web to the tension and the compression flanges,
stress Category Fstress Category F. . Cracks have been observed in plate gird-Cracks have been observed in plate gird-
ers at the junction of the web to the compression flange of ers at the junction of the web to the compression flange of 
runway girders when fillet welds are used to connect therunway girders when fillet welds are used to connect the
web to the compression flange. Such cracking has beenweb to the compression flange. Such cracking has been
traced to localized tension bending stresses in the bottomtraced to localized tension bending stresses in the bottom
side of compression flange plate with each wheel load pas-side of compression flange plate with each wheel load pas-
sage. Each wheel passage may occur two sage. Each wheel passage may occur two or four (or more)or four (or more)
times with each passage of the crane; thus, the life cyclestimes with each passage of the crane; thus, the life cycles
for this consideration is generally several times greater thanfor this consideration is generally several times greater than
the life cycles to be considered in the life cycles to be considered in the girder live load stressthe girder live load stress
ranges, due to passranges, due to passage of the loaded craneage of the loaded crane. . The calculationThe calculation
of such highly localized tensile bending stresses is so com-of such highly localized tensile bending stresses is so com-
 plex and unreliable that  plex and unreliable that the problem is buried the problem is buried in conserva-in conserva-
tive detail requiretive detail requirements. ments. TTo reduce the likelihood of sucho reduce the likelihood of such
cracks the AISE Teccracks the AISE Technical Report No. hnical Report No. 13 recommends that13 recommends that
the top flange to web joint be a full penetration weld, withthe top flange to web joint be a full penetration weld, with
fillet reinforcement.fillet reinforcement.
TiebacksTiebacks
Tiebacks are provided at the end of the crane runway gird-Tiebacks are provided at the end of the crane runway gird-
ers to transfer lateral forces from the girder top flange intoers to transfer lateral forces from the girder top flange into
the crane column and to laterally restrain the top flange of the crane column and to laterally restrain the top flange of 
the crane girder against buckling. The tiebacks must havethe crane girder against buckling. The tiebacks must have
adequate strength to transfer the lateral crane loads. How-adequate strength to transfer the lateral crane loads. How-
ever, the tiebacks must also be flexible enough to allow for ever, the tiebacks must also be flexible enough to allow for 
longitudinal movement of the top of the girder caused bylongitudinal movementof the top of the girder caused by
girder end rotation. girder end rotation. The amount of longitThe amount of longitudinal movementudinal movement
due to the end due to the end rotation of the girder can be rotation of the girder can be significant. Thesignificant. The
end rotation of a 40-foot girder that has undergone a deflec-end rotation of a 40-foot girder that has undergone a deflec-
tion of span over 600 is about 0.005 rtion of span over 600 is about 0.005 radians. adians. For a 36-inchFor a 36-inch
deep girder this results in 0.2 in. of deep girder this results in 0.2 in. of horizontal movement athorizontal movement at
the top flange. The tieback must also allow for verticalthe top flange. The tieback must also allow for vertical
movement due to axial shortening of the crane column.movement due to axial shortening of the crane column.
This vertical movement can be in the range of ¼ in. In gen-This vertical movement can be in the range of ¼ in. In gen-
eral, the tieback should be attached directly to the top eral, the tieback should be attached directly to the top flangeflange
of the girder. Attachment to the web of the girder with aof the girder. Attachment to the web of the girder with a
diaphragm plate should be avoided. The lateral load pathdiaphragm plate should be avoided. The lateral load path
for this detail causes bending stresses in the girder web per-for this detail causes bending stresses in the girder web per-
 pendicular to the gir pendicular to the girder cross section. der cross section. The diaphragm plaThe diaphragm platete
also tends to resist movement due to the axial shortening of also tends to resist movement due to the axial shortening of 
the crane column. Various AISC fatigue provisions arethe crane column. Various AISC fatigue provisions are
applicable to the loads depending on the exact tieback con-applicable to the loads depending on the exact tieback con-
figurations.figurations.
 Bearing Stiff Bearing Stiffenerseners
Bearing stiffeners should be provided at the ends of theBearing stiffeners should be provided at the ends of the
girders as required by the AISCgirders as required by the AISC SpecificationSpecification (1999) Para-(1999) Para-
graphs K1.3 and K1.4. graphs K1.3 and K1.4. Fatigue cracks have ocFatigue cracks have occurred at thecurred at the
connection between the bearing stiffener and the girder topconnection between the bearing stiffener and the girder top
flange. The cracks occurred in details where the bearingflange. The cracks occurred in details where the bearing
stiffener was fillet welded to the underside of the top flange.stiffener was fillet welded to the underside of the top flange.
Passage of each crane wheel produces shear stress in the fil-Passage of each crane wheel produces shear stress in the fil-
let welds. The AISC (1999) fatigue provisions containlet welds. The AISC (1999) fatigue provisions contain
fatigue criteria for fillet welds in fatigue criteria for fillet welds in shear; however, the deter-shear; however, the deter-
mination of the actual stress state in the mination of the actual stress state in the welds is extremelywelds is extremely
complex, thus the AISEcomplex, thus the AISE Technical Report No. 13Technical Report No. 13 recom-recom-
mends that full penetration welds be used to connect the topmends that full penetration welds be used to connect the top
of the bearing stiffeners to the top flange of the girdeof the bearing stiffeners to the top flange of the girder. r. TheThe
 bottom of the bear bottom of the bearing stiffenering stiffeners may be fitted s may be fitted (preferred) or (preferred) or 
fillet welded to the bottom flange. All stiffeners to girder fillet welded to the bottom flange. All stiffeners to girder 
webs welds should webs welds should be continuous. be continuous. Horizontal cracHorizontal cracks haveks have
 been  been observed observed in in the the webs webs of of crane crane girders girders with with partialpartial
height bearing stiffeheight bearing stiffeners. ners. The cracks start between the beaThe cracks start between the bear-r-
ing stiffeners and the top flange and run longitudinallying stiffeners and the top flange and run longitudinally
along the web of the girder. along the web of the girder. There are many possible causesThere are many possible causes
for the propagation of these cracks. One possible explana-for the propagation of these cracks. One possible explana-
tion is that eccentricity in the placement of the rail on thetion is that eccentricity in the placement of the rail on the
girder causes distortion of the girder cross-section and rota-girder causes distortion of the girder cross-section and rota-
tion of the girder cross-section.tion of the girder cross-section.
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 4747
    
 Intermediate S Intermediate Stiffenerstiffeners
If intermediate stiffeners are used, the AISEIf intermediate stiffeners are used, the AISE Technical Technical 
 Report No. 13 Report No. 13 also recommends that the intermediate stiff-also recommends that the intermediate stiff-
eners be welded to the top flange with full penetrationeners be welded to the top flange with full penetration
welds for the same reasons as with bearing stiffeners. welds for the same reasons as with bearing stiffeners. StiffStiff--
eners should be stopped short of the tension flange in accor-eners should be stopped short of the tension flange in accor-
dance with the AISCdance with the AISC SpecificationSpecification (1999) provisions(1999) provisions
contained in Chaptecontained in Chapter Gr G. . The AISE The AISE Technical Report No. 13Technical Report No. 13
also recommends continuous stiffener to web welds for also recommends continuous stiffener to web welds for 
intermediate stiffeners.intermediate stiffeners.
Fatigue must be checked where the stiffener terminatesFatigue must be checked where the stiffener terminates
adjacent to the tensadjacent to the tension flange. ion flange. This condition is This condition is addressedaddressed
in Section 5.7, Table A-K3.1, of the 1999 AISC specifica-in Section 5.7, Table A-K3.1, of the 1999 AISC specifica-
tions.tions.
Channel Caps and Cap PlatesChannel Caps and Cap Plates
Channel caps or cap plates are frequently used to provideChannel caps or cap plates are frequently used to provide
adequate top flange capacity to transfer lateral loads to theadequate top flange capacity to transfer lateral loads to the
crane columns and to provide adequate lateral torsional sta-crane columns and to provide adequate lateral torsional sta-
 bility of  bility of the runway girthe runway girder cross secder cross section. tion. It should be It should be notednoted
that the cap channel or plate does not that the cap channel or plate does not fit perfectly with 100fit perfectly with 100
 percent  percent bearing bearing on on the the top top of of the the wide wide flange. flange. The The toler-toler-
ances given in ASTM A6 allow the wide flange ances given in ASTM A6 allow the wide flange member tomember to
have some flange tilt along its length, or the plate may behave some flange tilt along its length, or the plate may be
cupped or slightly warped, or the channel may have somecupped or slightly warped, or the channel may have some
twist along its length. These conditions will leave smalltwist along its length. These conditions will leave small
gaps between the top flange of the girder and the top plategaps between the top flange of the girder and the top plate
or channel. or channel. The passage of the crane The passage of the crane wheel over these gapswheel over these gaps
will tend to distress the channel or plate to top flange welds.will tend to distress the channel or plate to top flange welds.
Calculation of the stress condition for these welds is notCalculation of thestress condition for these welds is not
 practical.  practical. Because of this pheBecause of this phenomenon, cap plates or nomenon, cap plates or chan-chan-
nels should not be unels should not be used with Class sed with Class E or F cranes. E or F cranes. For lessFor less
severe duty cycle cranes, shear flow stress in the welds cansevere duty cycle cranes, shear flow stress in the welds can
 be  be calculated calculated and and limited limited according according to to the the AISC AISC (1999)(1999)
fatigue provisions in Appendix K3, Table A-K3.1, Sectionfatigue provisions in Appendix K3, Table A-K3.1, Section
8.2. The channel or plate welds to the 8.2. The channel or plate welds to the top flange can be top flange can be con-con-
tinuous or intermittent. However, the AISC design stresstinuous or intermittent. However, the AISC design stress
range for the base metal is reduced from Category B (Sec-range for the base metal is reduced from Category B (Sec-
tion 3.1) for continuous welds to Category E (Section 3.4)tion 3.1) for continuous welds to Category E (Section 3.4)
for intermittent welds.for intermittent welds.
Crane Column Cap PlatesCrane Column Cap Plates
The crane column cap plate should be detailed so as to notThe crane column cap plate should be detailed so as to not
restrain the end rotation of the girderrestrain the end rotation of the girder. . If the cap plate girder If the cap plate girder 
 bolts are p bolts are placed between laced between the column fthe column flanges, a forlanges, a force couplece couple
 between the  between the column flange column flange and the and the bolts resists bolts resists the girder the girder 
end rotation. end rotation. This detail has beeThis detail has been known to cause bolt failn known to cause bolt fail--
ures. ures. PreferablyPreferably, the girder should be bolted to the cap plate, the girder should be bolted to the cap plate
outside of the column foutside of the column flanges. langes. The column cap platThe column cap plate shoulde should
 be extended outside  be extended outside of the of the column flange with column flange with the bolts tothe bolts to
the girder plthe girder placed outside of aced outside of the column flthe column flanges. anges. The col-The col-
umn cap plate should not be made overly thick, as thisumn cap plate should not be made overly thick, as this
detail requires the cap plate to distort to allow for the enddetail requires the cap plate to distort to allow for the end
rotation of the girder. The girder to cap plate bolts should rotation of the girder. The girder to cap plate bolts should bebe
adequate to transfer the tractive or bumper forces to the lon-adequate to transfer the tractive or bumper forces to the lon-
gitudinal crane bracing. Traction plates between girder gitudinal crane bracing. Traction plates between girder 
webs may be required for large tractive forces or bumper webs may be required for large tractive forces or bumper 
forces. The engineer should consider using forces. The engineer should consider using finger tight boltsfinger tight bolts
with upset threads as a means of reducing bolt fatigue inwith upset threads as a means of reducing bolt fatigue in
crane column cap plates (Rolfes, 2001).crane column cap plates (Rolfes, 2001).
 Miscellaneous Att Miscellaneous Attachmentsachments
Attachments to crane runway girders should be avoided.Attachments to crane runway girders should be avoided.
The AISEThe AISE Technical Report No. 13Technical Report No. 13 specifically prohibitsspecifically prohibits
welding attachments to the tension flange of runway gird-welding attachments to the tension flange of runway gird-
ers. ers. Brackets to support the runway electBrackets to support the runway electrification are oftenrification are often
necessarynecessary. . If the bracketIf the brackets are bolted s are bolted to the web to the web of theof the
girder, fatigue consequences are relatively minor, i.e. stressgirder, fatigue consequences are relatively minor, i.e. stress
category B, Section 1.3 category B, Section 1.3 of the AISC (1999) fatigue specifi-of the AISC (1999) fatigue specifi-
cations. However, if the attachment is made with filletcations. However, if the attachment is made with fillet
welds to the web Appendix K3, Table A-K3.1, Section 7.2welds to the web Appendix K3, Table A-K3.1, Section 7.2
of the AISCof the AISC SpecificationSpecification applies. applies. This provisiThis provision places theon places the
detail into stress catedetail into stress category D or E depending on the detailgory D or E depending on the detail. . If If 
transverse stiffeners are present, the brackets should betransverse stiffeners are present, the brackets should be
attached to the attached to the stiffeners.stiffeners.
1313.. CRCRANANE IE INDNDUCUCED ED LOLOADADS S ANAND LD LOAOAD CD COMOM--
BINATIONSBINATIONS
It is recommended that the designer shows on It is recommended that the designer shows on the drawingsthe drawings
the crane wheel loads, wheel spacing, bumper forces, andthe crane wheel loads, wheel spacing, bumper forces, and
the design criteria used to design the the design criteria used to design the structure.structure.
Although loading conditions for gravity, wind, and seis-Although loading conditions for gravity, wind, and seis-
mic loads are well defined among building codes and stan-mic loads are well defined among building codes and stan-
dards, crane loading conditions generally are not.dards, crane loading conditions generally are not.
As mentioned previously, crane fatigue loadings are As mentioned previously, crane fatigue loadings are pri-pri-
marily a function of the class of service, which in turn ismarily a function of the class of service, which in turn is
 based primarily on the number of cycles of a specific load- based primarily on the number of cycles of a specific load-
ing case. This classification should be based on the esti-ing case. This classification should be based on the esti-
mated life span, rate of loading, and the number of loadmated life span, rate of loading, and the number of load
repetitions. The owner should specify or approve the classi-repetitions. The owner should specify or approve the classi-
fication for all fication for all portions of a buportions of a building. ilding. AA maximum life maximum life spanspan
of 50 years is of 50 years is generally accepted.generally accepted.
The provisions of the American Society of Civil Engi-The provisions of the American Society of Civil Engi-
neers (ASCE, 2002) and the Association of Iron and Steelneers (ASCE, 2002) and the Association of Iron and Steel
Engineers (AISE, 2003) on crane runway Engineers (AISE, 2003) on crane runway loads are summa-loads are summa-
rized in the following drized in the following discussion. iscussion. ASCE 7 is refASCE 7 is referenced byerenced by
the International Building Code (ICC 2003), and is a legalthe International Building Code (ICC 2003), and is a legal
requirement. AISErequirement. AISE Technical Report No. 13Technical Report No. 13 is a guidelineis a guideline
and can be used for situations not covered by ASCE 7, or and can be used for situations not covered by ASCE 7, or 
when specified by project specifications. In addition, thewhen specified by project specifications. In addition, the
MBMAMBMA  Low  Low Rise Rise Building Building Systems Systems Manual Manual  (MBMA,(MBMA,
2002) provides a comprehensive discussion on crane loads.2002) provides a comprehensive discussion on crane loads.
AISEAISE Technical Report 13Technical Report 13 recommendations are basedrecommendations are based
on ASD design provisions, whereas ASCE 7 provisions on ASD design provisions, whereas ASCE 7 provisions areare
4848 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS ROOFSROOFS TO ANCHOR RODSTO ANCHOR RODS 2ND EDITION2ND EDITION
4848 / DESI/ DESIGN GUIDGN GUIDE 7 /E 7 / INDUSTRIAL BUILDINGSINDUSTRIALBUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION
    
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS ROOFSROOFS TO ANCHOR RODSTO ANCHOR RODS 2ND EDITION2ND EDITION // 4949
given for both Strength Design and Allowable Stressgiven for both Strength Design and Allowable Stress
Design. ASDesign. ASCE 7 indicates that the CE 7 indicates that the live load of a live load of a crane is thecrane is the
rated capacityrated capacity. . No comments are No comments are made about appropriatmade about appropriatee
load factors relative to the trolley, hoist, or bridge weight.load factors relative to the trolley, hoist, or bridge weight.
The author recommends using a 1.2 load factor for theThe author recommends using a 1.2 load factor for the
 bridge weight and a 1.6 load factor for the hoi bridge weight and a 1.6 load factor for the hoist and trolleyst and trolley
weight.weight.
1313.1.1 VVerertiticacal Impl Impacactt
 ASCE 7  ASCE 7 
ASCE 7 defines the maximum wheel load as follows: “TheASCE 7 defines the maximum wheel load as follows: “The
maximum wheel loads shall be the wheel loads produced bymaximum wheel loads shall be the wheel loads produced by
the weight of the bridge, as applicable, plus the sum of thethe weight of the bridge, as applicable, plus the sum of the
rated capacity and the weight of rated capacity and the weight of the trolley with the trolleythe trolley with the trolley
 positioned on its runwa positioned on its runway at the location where the ry at the location where the resultingesulting
load effect is maximum.” Vertical impact percentages areload effect is maximum.” Vertical impact percentages are
then multiplied by the maximum wheel loads. The percent-then multiplied by the maximum wheel loads. The percent-
age factors contained in ASCE 7 are age factors contained in ASCE 7 are as follows:as follows:
MMoonnoorraaiil l ccrraannees s ((ppoowweerreedd)) 2255
Cab-operated or remotely operatedCab-operated or remotely operated
 bridge cranes (powered) bridge cranes (powered) 2525
PPeennddaanntt--ooppeerraatteed bd brriiddgge ce crraannees (s (ppoowweerreedd)) 1100
Bridge cranes or monorail cranes withBridge cranes or monorail cranes with
hhaanndd--ggeeaarreed d bbrriiddggee, , ttrroolllleeyy, , aannd d hhooiisstt 00
 AISE T AISE Technical Report No. 13echnical Report No. 13
The allowances for vertical impact are specified as 25 per-The allowances for vertical impact are specified as 25 per-
cent of the maximum wheel loads for cent of the maximum wheel loads for all crane types, exceptall crane types, except
a 20 percent impact factor is a 20 percent impact factor is recommended for motor roomrecommended for motor roommaintenance cranes, etc.maintenance cranes, etc.
In all cases, impact loading should be considered in theIn all cases, impact loading should be considered in the
design of column brackets design of column brackets regardless of whether ASCE 7 or regardless of whether ASCE 7 or 
AISEAISE Technical Report 13Technical Report 13 requirements are being used.requirements are being used.
1313.2.2 SiSide de ThThrrusustt
Horizontal forces exist in crane loadings due to a number of Horizontal forces exist in crane loadings due to a number of 
factors including:factors including:
1.1. RRununwway ay mmisisaaliligngnmmenentt
22.. CCrraanne e sskkeeww
3.3. TTrrololleley acy accecellereratatiionon
44.. TTrroolllleey y bbrraakkiinngg
55.. CCrraanne se stteeeerriinngg
 ASCE 7  ASCE 7 
“The lateral force on crane runway beams with electrically“The lateral force on crane runway beams with electrically
 powered  powered trolleys trolleys shall shall be be calculated calculated as as 20 20 percent percent of of thethe
sum of the rated capacity of the sum of the rated capacity of the crane and the weight of thecrane and the weight of the
hoist and trolley. The lateral force shall be assumed to acthoist and trolley. The lateral force shall be assumed to act
horizontally at the traction surface on a runway beam, inhorizontally at the traction surface on a runway beam, in
either direction perpendicular to the beam, and either direction perpendicular to the beam, and shall be dis-shall be dis-
tributed with due regard to the lateral stiffness of the run-tributed with due regard to the lateral stiffness of the run-
way beam and supporting structure.”way beam and supporting structure.”
 AISE T AISE Technical Report No. 13echnical Report No. 13
The AISEThe AISE Technical Report 13Technical Report 13 requires that “The recom-requires that “The recom-
mended total side thrust shall be distributed with due regardmended total side thrust shall be distributed with due regard
for the lateral stiffness of the for the lateral stiffness of the structures supporting the railsstructures supporting the rails
and shall be the greatest of:and shall be the greatest of:
1.1. ThaThat spt speciecifiefied in Td in Tablable 3.2 e 3.2 [S[Showhown hern here as Te as Tablablee
13.2.1].13.2.1].
2.2. 20 pe20 percercent ont of thf the coe combimbined ned weiweight ght of tof the lhe liftifted led loadoadand trolley. For stacker cranes this factor shall be 40and trolley. For stacker cranes this factor shall be 40
 percent of th percent of the combined wee combined weight of the ight of the lifted load, lifted load, trol-trol-
ley and rigid arm.ley and rigid arm.
3.3. 10 pe10 percercent ont of thf the coe combimbined ned weiweight ght of tof the lhe liftifted led loadoad
and crane weight. and crane weight. For stacker craneFor stacker cranes this factor shalls this factor shall
 be 15  be 15 percent of percent of the combithe combined weight ned weight of the of the lifted llifted loadoad
and the crane weight.”and the crane weight.”
In the AISEIn the AISE Technical Report 13Technical Report 13 lifted load is defined as:lifted load is defined as:
“a total weight lifted by the hoist mechanism, including“a total weight lifted by the hoist mechanism, including
working load, all hooks, lifting beams, magnets or other working load, all hooks, lifting beams, magnets or other 
appurtenances required by the service but excluding theappurtenances required by the service but excluding the
weight of column, ram or other material handling deviceweight of column, ram or other material handling device
which is rigidly guided in a vertical direction during hoist-which is rigidly guided in a vertical direction during hoist-
ing action.”ing action.”
Table 13.2.1 Table 13.2.1 AISE Report 13 AISE Report 13 Crane Side ThrustsCrane Side Thrusts
Crane TypeCrane Type
Total side thrustTotal side thrust
percent of lifted loadpercent of lifted load
Mill craneMill crane
Ladle cranesLadle cranes
Clamshell bucket andClamshell bucket and
magnet cranesmagnet cranes
(including slab and(including slab and
billet yard cranes)billet yard cranes)
Soaking pit cranesSoaking pit cranes
Stripping cranesStripping cranes
Motor roomMotor room
maintenance cranes, etc.maintenance cranes, etc.
Stacker cranes (cab-Stacker cranes (cab-
operated)operated)
4040
4040
100100
100100
100100↑↑  
3030
200200
↑↑ ingot and mold ingot and mold
DESIGN GUIDE 7 /DESIGN GUIDE 7 / INDUSTRIAL BUILDINGSINDUSTRIAL BUILDINGS—ROOFS —ROOFS TO ANCHOR RODS,TO ANCHOR RODS, 2ND EDITION2ND EDITION / / 4949
    
For pendant operated cranes, the AISEFor pendant operated cranes, the AISE Technical Report 13Technical Report 13
side thrust is taken as 20 percent of the maximum load onside thrust is taken as 20 percent of the maximum load on
the driving wheels. the driving wheels. In most cases one half of the wheels areIn most cases one half of the wheels are
driving wheels.driving wheels.
AISEAISE Technical Report 13Technical Report 13 requires that radio-operatedrequires that radio-operated
cranes be considered as cab-operated cranes with regard tocranes be considered as cab-operated cranes with regard to
side thrusts.side thrusts.
Table