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North American Specification for the Design of Cold-Formed SteelStructural Members

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AMERICANSPECIFICATION

FOR THE DESIGN OFCOLD-FORMED STEELSTRUCTURAL MEMBERS

(.PDF)

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North AmericanSpecification for the

Design ofCold-Formed SteelStructural Membersand Commentary

For over 50years, the American Iron and Steel Institute has published the widely usedSpecification for the Design of Cold-Formed Steel StructuralMembers.

Recently, as a result of collaborative efforts with representativesof Canada and Mexico, the AISI Specification was expanded intoa new document for use in all three countries.

Now known as the North American Specification for the Design oCold-Formed Steel Structural Members, the new editionsupersedes the previous AISI Specification and the CanadianS136 Standard.

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NASPEC Table of Contents(.PDF)

Paper Discussing Diference Between NASPEC 1996 and 2001(.PDF)

SUMMARY OF MAJOR CHANGES AND IMPROVEMENTS IN THE 2001 NORTH AMERICANSPECIFICATION FOR THE DESIGN OF COLD-FORMED STEEL STRUCTURAL MEMBERS(.PDF)

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2001(.PDF)

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AMERICAN SPECIFICATIONFOR THE DESIGN OF COLD-

FORMED STEELSTRUCTURAL MEMBERS(.

PDF)

Buy It Now:

North AmericanSpecification for the Design

ofCold-Formed SteelStructural Membersand Commentary

..

Frequently Asked Questions

About theNorth American Specifications for the

Design of Cold-Formed Steel Structural Members

Question:What's special about this edition of the North American Specification?

Answer: This is the first edition of the North American Specification for the Design of CoFormed Steel Structural Members, which is an ANSI-approved American National Standaapproved in Canada by Canadian Standards Association (CSA) and approved in Mexico byCANACERO. The Specification is intended for use throughout the United States, Canada, Mexico.

Question:What are the benefits of having this North American Specification?

Answer:There are several benefits, which include the following:

It will raise cold-formed steel design technology to the same level in all NAFTA coun

Since this Specification is the foundation for the design of major cold-formed produincluding steel decking, standing-seam roofing, steel building systems, storage rackcold-formed framing, the unified Specification will enhance the cold-formed steel inin the region. Standardization of engineering will also allow faster introduction of netechnologies.

Manufacturers of steel construction products should see increased productivity becathey will no longer need to re-engineer their products or systems to different stand

Designers who practice across borders will no longer need to learn multiple designstandards.

Wider dissemination of software and design aids will allow those previously unfamilthe design of cold-formed steel to more easily learn to design with steel technologySpecification will also provide AISI, CSA and CANACERO with the opportunity to devand distribute a wide variety of derivative products.

Question:How was the Specification written?

Answer:This first edition of the North American Specification was developed based on t

American Iron and Steel Institute's (AISI) Specification for the Design of Cold-Formed StStructural Members and the Canadian Standards Association's (CSA) Standard S136-94,Formed Steel Structural Members. This first edition was the result of a cooperative effortNorth American Specification Committee (from the U.S., Canada and Mexico), the AISICommittee on Specifications for the Design of Cold-Formed Steel Structural Members, anCSA Committee on Cold Formed Steel Structural Members.

Question:How will the new Specification affect previous ones?

Answer:The North American Specification will supersede the previous editions of theSpecification for the Design of Cold-Formed Steel Structural Members, published by AmeIron and Steel Institute; and the previous editions of CSA Standard S136, Cold Formed SStructural Members, published by the Canadian Standards Association.

Question:Is the North American Specification approved by ANSI?
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.

Answer:Yes. The North American Specification is approved by American National StandInstitute (ANSI) as the American National Standard. The designation number is AISI/COSNASPEC 2001, and the approval date is June 5, 2002.

Question:Are there any documents or articles that explain the differences between the Specification edition and this new edition?

Answer:Comparisons and reviews are provided in the following articles:

1. Technical Bulletin published by Wei-Wen Yu Center for Cold-Formed Steel Structures,Summary of Major Changes and Improvements in the 2001 North American SpecificationDesign of Cold-Formed Steel Structural Members.

2. Paper by Roger Brockenbrough and Helen Chen, North American Specification for DesCold-Formed Steel

Question:How is the North American Specification structured?

Answer:The North American Specification includes a main document, Chapters A througthat is intended for use in all three countries (the United States, Canada, and Mexico), athree country-specific appendices (A to C).

Appendix A is for use in the United States,

Appendix B is for use in Canada, and Appendix C is for use in Mexico. This Specification pan integrated treatment of Allowable Strength Design (ASD), Load and Resistance Factor(LRFD), and Limit States Design (LSD).

This is accomplished by including the appropriate resistance factors (f) for use with LRFDLSD, and the appropriate factors of safety (W) for use with ASD. It should be noted that limited to Canada and LRFD and ASD are limited to the United States and Mexico.

A table of contents for the Specification is provided.

Question:How do I order the Specification and the Commentary and what is the cost?

Answer:The publications can be ordered through the AISI website e-Store by following links below. You can also call 1-800-277-3850 to place the order.

The publication number and the price are as follows:

Publications/Publication Number Pric

Both Specification and Commentary SG02-1 and SG02-2 $99.

About | Search | Site Map | Contact | Shop | Privacy PolicyCopyright 2005, American Iron and Steel Institute
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North American Cold-Formed Steel Specification

December 2001 9

TABLE OF CONTENTS

NORTH AMERICAN SPECIFICATION FOR THE DESIGN OF

COLD-FORMED STEEL STRUCTURAL MEMBERS

2001 EDITIONPREFACE................................................................................................................................................3

SYMOBLS AND DEFINITIONS ..............................................................................................................15

A. GENERAL PROVISIONS .................................................................................................................33A1 Limits of Applicability and Terms ............................................................................................. 33

A1.1 Scope and Limits of Applicability................................................................................... 33A1.2 Terms ............................................................................................................................... 34A1.3 Units of Symbols and Terms............................................................................................37

A2 Material .......................................................................................................................................... 37A2.1 Applicable Steels ............................................................................................................... 37A2.2 Other Steels ........................................................................................................................ 38A2.3 Ductility.............................................................................................................................. 38A2.4 Delivered Minimum Thickness.......................................................................................40

A3 Loads .............................................................................................................................................. 40A4 Allowable Strength Design ......................................................................................................... 40

A4.1 Design Basis ....................................................................................................................... 40A4.1.1 ASD Requirements............................................................................................. 40A4.1.2 Load Combinations for ASD............................................................................. 41

A5 Load and Resistance Factor Design ........................................................................................... 41A5.1 Design Basis ....................................................................................................................... 41

A5.1.1 LRFD Requirements...........................................................................................41A5.1.2 Load Factors and Load Combinations for LRFD ...........................................41

A6 Limit States Design....................................................................................................................... 41A6.1 Design Basis ....................................................................................................................... 41A6.1.1 LSD Requirements.............................................................................................. 41A6.1.2 Load Factors and Load Combinations for LSD.............................................. 42

A7 Yield Point and Strength Increase from Cold Work of Forming ...........................................42A7.1 Yield Point.......................................................................................................................... 42A7.2 Strength Increase from Cold Work of Forming ............................................................42

A8 Serviceability................................................................................................................................. 43A9 Referenced Documents ................................................................................................................ 43

B. ELEMENTS....................................................................................................................... ..............45B1

Dimensional Limits and Considerations................................................................................... 45

B1.1 Flange Flat-Width-to-Thickness Considerations .......................................................... 45B1.2 Maximum Web Depth-to-Thickness Ratios...................................................................46

B2 Effective Widths of Stiffened Elements ..................................................................................... 47B2.1 Uniformly Compressed Stiffened Elements.................................................................. 47B2.2 Uniformly Compressed Stiffened Elements with Circular Holes .............................. 49B2.3 Webs and other Stiffened Elements under Stress Gradient ........................................ 49B2.4 C-Section Webs with Holes under Stress Gradient ......................................................51

B3 Effective Widths of Unstiffened Elements................................................................................ 52


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Table of Contents

10 December 2001

B3.1 Uniformly Compressed Unstiffened Elements............................................................. 52B3.2 Unstiffened Elements and Edge Stiffeners under Stress Gradient............................. 52

B4 Effective Widths of Elements with One Intermediate Stiffener or an Edge Stiffener......... 53B4.1 Uniformly Compressed Elements with One Intermediate Stiffener.......................... 53B4.2 Uniformly Compressed Elements with an Edge Stiffener........................................... 54

B5

Effective Widths of Stiffened Elements with Multiple Intermediate Stiffeners or EdgeStiffened Elements with Intermediate Stiffeners...................................................................... 56B5.1 Effective Widths of Uniformly Compressed Stiffened Elements with Multiple

Intermediate Stiffeners ..................................................................................................... 56B5.1.1 Specific Case: n Identical Stiffeners, Equally Spaced .................................. 57B5.1.2 General Case: Arbitrary Stiffener Size, Location and Number.................... 57

B5.2 Edge Stiffened Elements with Intermediate Stiffeners ................................................ 59C. MEMBERS ........................................................................................................................ .............60

C1 Properties of Sections................................................................................................................... 60C2 Tension Members ......................................................................................................................... 60C3 Flexural Members......................................................................................................................... 60

C3.1 Bending ............................................................................................................................... 60C3.1.1 Nominal Section Strength [Resistance] ........................................................... 60C3.1.2 Lateral-Torsional Buckling Strength [Resistance].......................................... 62

C3.1.2.1 Lateral-Torsional Buckling Strength [Resistance] of Open CrossSection Members...............................................................................62

C3.1.2.2 Lateral-Torsional Buckling Strength [Resistance] of Closed BoxMembers ............................................................................................ 65

C3.1.3 Beams Having One Flange Through-Fastened to Deck or Sheathing......... 65C3.1.4 Beams Having One Flange Fastened to a Standing Seam Roof System ..... 67C3.1.5 Strength [Resistance] of Standing Seam Roof Panel Systems ......................67

C3.2 Shear ............................................................................................................................... 68C3.2.1 Shear Strength [Resistance] of Webs without Holes .....................................68C3.2.2 Shear Strength [Resistance] of C-Section Webs with Holes ......................... 69

C3.3 Combined Bending and Shear......................................................................................... 69C3.3.1 ASD Method........................................................................................................ 69C3.3.2 LRFD and LSD Methods.................................................................................... 70

C3.4 Web Crippling ................................................................................................................... 71C3.4.1 Web Crippling Strength [Resistance] of Webs without Holes..................... 71C3.4.2 Web Crippling Strength [Resistance] of C-Section Webs with Holes........ 74

C3.5 Combined Bending and Web Crippling ........................................................................75C3.5.1 ASD Method........................................................................................................ 75C3.5.2 LRFD and LSD Methods.................................................................................... 77

C3.6 Stiffeners............................................................................................................................. 79C3.6.1 Transverse Stiffeners.......................................................................................... 79C3.6.2 Shear Stiffeners ..................................................................................................80C3.6.3 Non-Conforming Stiffeners............................................................................... 80

C4 Concentrically Loaded Compression Members....................................................................... 81C4.1 Sections Not Subject to Torsional or Torsional-Flexural Buckling.............................81C4.2 Doubly- or Singly-Symmetric Sections Subject to Torsional or Torsional-Flexural

Buckling..............................................................................................................................82


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December 2001 11

C4.3 Point-Symmetric Sections................................................................................................. 82C4.4 Nonsymmetric Sections.................................................................................................... 83C4.5 Built-Up Members............................................................................................................. 83C4.6 Compression Members Having One Flange Through-Fastened to Deck or

Sheathing............................................................................................................................ 83C5

Combined Axial Load and Bending .......................................................................................... 85

C5.1 Combined Tensile Axial Load and Bending..................................................................85

C5.1.1 ASD Method........................................................................................................ 85C5.1.2 LRFD and LSD Methods.................................................................................... 86

C5.2 Combined Compressive Axial Load and Bending ....................................................... 86C5.2.1 ASD Method........................................................................................................ 86C5.2.2 LRFD and LSD Methods.................................................................................... 88

C6 Closed Cylindrical Tubular Members ....................................................................................... 91C6.1 Bending ............................................................................................................................... 91C6.2 Compression ...................................................................................................................... 91C6.3 Combined Bending and Compression ........................................................................... 92

D. STRUCTURAL ASSEMBLIES..........................................................................................................93D1 Built-Up Sections .......................................................................................................................... 93

D1.1 I-Sections Composed of Two C-Sections........................................................................ 93D1.2 Spacing of Connections in Compression Elements ...................................................... 94

D2 Mixed Systems ..............................................................................................................................94D3 Lateral Bracing..............................................................................................................................94

D3.1 Symmetrical Beams and Columns.................................................................................. 94D3.2 C-Section and Z-Section Beams....................................................................................... 94

D3.2.1 Anchorage of Bracing for Roof Systems Under Gravity Load With TopFlange Connected to Sheathing........................................................................ 95

D3.2.2 Neither Flange Connected to Sheathing.......................................................... 97D4 Wall Studs and Wall Stud Assemblies ...................................................................................... 98

D4.1 Compression ...................................................................................................................... 99D4.2 Bending ............................................................................................................................. 102D4.3 Combined Axial Load and Bending............................................................................. 102

D5 Floor, Roof or Wall Steel Diaphragm Construction...............................................................102E. CONNECTIONS AND JOINTS....................................................................................................... 104

E1 General Provisions ..................................................................................................................... 104E2 Welded Connections .................................................................................................................. 104

E2.1 Groove Welds in Butt Joints........................................................................................... 104E2.2 Arc Spot Welds ................................................................................................................ 105

E2.2.1 Shear ........................................................................................................... 104E2.2.2 Tension ........................................................................................................... 108E2.3 Arc Seam Welds............................................................................................................... 104E2.4 Fillet Welds....................................................................................................................... 110E2.5 Flare Groove Welds......................................................................................................... 112E2.6 Resistance Welds ............................................................................................................. 114E2.7 Fracture in Net Section of Members other than Flat Sheets (Shear Lag).................115

E3 Bolted Connections..................................................................................................................... 116


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Table of Contents

12 December 2001

E3.1 Shear, Spacing and Edge Distance................................................................................ 116E3.2 Fracture in Net Section (Shear Lag) .............................................................................. 117E3.3 Bearing ............................................................................................................................. 117

E3.3.1 Strength [Resistance] without Consideration of Bolt Hole Deformation. 117E3.3.2 Strength [Resistance] with Consideration of Bolt Hole Deformation....... 118

E3.4

Shear and Tension in Bolts............................................................................................. 118

E4 Screw Connections ..................................................................................................................... 118E4.1 Minimum Spacing........................................................................................................... 119E4.2 Minimum Edge and End Distances.............................................................................. 119E4.3 Shear ............................................................................................................................. 119

E4.3.1 Connection Shear Limited by Tilting and Bearing ...................................... 119E4.3.2 Connection Shear Limited by End Distance................................................. 120E4.3.3 Shear in Screws .................................................................................................120

E4.4 Tension ............................................................................................................................. 120E4.4.1 Pull-Out ........................................................................................................... 120E4.4.2 Pull-Over ........................................................................................................... 120E4.4.3 Tension in Screws............................................................................................. 120

E5 Rupture ........................................................................................................................................ 120E6 Connections to Other Materials................................................................................................ 121

E6.1 Bearing ............................................................................................................................. 121E6.2 Tension ............................................................................................................................. 121E6.3 Shear ............................................................................................................................. 121

F. TESTS FOR SPECIAL CASES ...................................................................................................... 122F1 Tests for Determining Structural Performance ...................................................................... 122

F1.1 Load and Resistance Factor Design and Limit States Design ................................... 122F1.2 Allowable Strength Design............................................................................................ 126

F2 Tests for Confirming Structural Performance ........................................................................ 126F3 Tests for Determining Mechanical Properties ........................................................................ 126

F3.1 Full Section....................................................................................................................... 126F3.2 Flat Elements of Formed Sections.................................................................................127F3.3 Virgin Steel ....................................................................................................................... 127

G. DESIGN OF COLD-FORMED STEEL STRUCTURAL MEMBERS AND CONNECTIONS FOR CYCLICLOADING (FATIGUE) ................................................................................................................... 128

G1 General......................................................................................................................................... 128G2 Calculation of Maximum Stresses and Stress Ranges ........................................................... 129G3 Design Stress Range ................................................................................................................... 129G4 Bolts and Threaded Parts .......................................................................................................... 130G5 Special Fabrication Requirements............................................................................................ 131

PREFACE TO APPENDIX A.................................................................................................................. A2APPENDIX A: PROVISIONS APPLICABLE TO THE UNITED STATES................................................... A3

A1.1aScope and Limits of Applicability..................................................................................A3A2.2 Other Steels ....................................................................................................................... A3

A3 Loads ............................................................................................................................................. A3A3.1 Nominal Loads .................................................................................................................A3

A4.1.2 Load Combinations for ASD............................................................................ A3


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December 2001 13

A5.1.2 Load Factors and Load Combinations for LRFD ..........................................A4A9aReferenced Documents ............................................................................................................... A4C2 Tension Members ........................................................................................................................ A4

C3.1.4 Beams Having One Flange Fastened to a Standing Seam Roof System ....A5E2a Welded Connections ...................................................................................................................A5E3a

Bolted Connections...................................................................................................................... A6

E3.1 Shear, Spacing and Edge Distance.................................................................................A7E3.2 Fracture in Net Section (Shear Lag) ...............................................................................A8E3.4 Shear and Tension in Bolts..............................................................................................A9

E4.3.2 Connection Shear Limited by End Distance................................................A14E5 Rupture .......................................................................................................................................A14

E5.1 Shear Rupture .................................................................................................................A14E5.2 Tension Rupture.............................................................................................................A14E5.3 Block Shear Rupture ...................................................................................................... A14

PREFACE TO APPENDIX B: ................................................................................................................ B2APPENDIX B: PROVISIONS APPLICABLE TO CANADA...................................................................... B3

A1.2aTerms ...............................................................................................................................B3A2.1aApplicable Steels ...............................................................................................................B3A2.2 Other Steels ........................................................................................................................B3

A2.2.1 Other Structural Quality Steels.........................................................................B3A2.2.2 Other Steels..........................................................................................................B3

A2.4aDelivered Minimum Thickness.......................................................................................B3A3 Loads ..............................................................................................................................................B4

A3.1 Specified Loads..................................................................................................................B4A3.2 Temperature Effects ..........................................................................................................B5

A6.1.2 Load Factors and Load Combinations for LSD..............................................B5A6.1.2.1 Load Factors () ................................................................................B5A6.1.2.2 Load Combination Factor () .........................................................B5A6.1.2.3 Importance Factor () .......................................................................B5

A9aReference Documents ..................................................................................................................B6C2 Tension Members .........................................................................................................................B6

C2.1 Yielding of Gross Section .................................................................................................B6C2.2 Fracture of Net Section .....................................................................................................B6

C3.1.4 Beams Having One Flange Fastened to a Standing Seam Roof System .....B7D3aLateral Bracing ..............................................................................................................................B7

D3.1aSymmetrical Beams and Columns..................................................................................B7D3.1.1 Discrete Bracing..................................................................................................B8D3.1.2 Bracing by Deck, Slab, or Sheathing................................................................B8

D3.2aC-Section and Z-Section Beams.......................................................................................B8D3.2.3 Discrete Bracing..................................................................................................B8D3.2.4 One Flange Braced by Deck, Slab, or Sheathing ............................................B8D3.2.5 Both Flanges Braced by Deck, Slab, or Sheathing..........................................B9

E2a Welded Connections ....................................................................................................................B9E2.2a Arc Spot Welds ..................................................................................................................B9E2.3a Arc Seam Welds.................................................................................................................B9

E3a Bolted Connections.....................................................................................................................B10


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Table of Contents

14 December 2001

E3.1 Shear, Spacing and Edge Distance................................................................................B10E3.2 Fracture in Net Section (Shear Lag) ..............................................................................B10E3.3a Bearing .............................................................................................................................B11E3.4 Shear and Tension in Bolts.............................................................................................B11

E4.3.2 Connection Shear Limited by End Distance.................................................B12E5

Rupture ........................................................................................................................................B12

APPENDIX C: PROVISIONS APPLICABLE TO MEXICO....................................................................... C3A1.1aCountry Specific Scope and Limits of Applicability ................................................... C3A2.2 Other Steels ....................................................................................................................... C3

A3 Loads ............................................................................................................................................. C3A3.1 Nominal Loads ................................................................................................................. C3

A4.1.2 Load Combinations for ASD............................................................................ C3A5.1.2 Load Factors and Load Combinations for LRFD .......................................... C4

A9aReferenced Documents ............................................................................................................... C4C2 Tension Members ........................................................................................................................ C5

C3.1.4 Beams Having One Flange Fastened to a Standing Seam Roof System .... C5E2a Welded Connections ................................................................................................................... C5E3a Bolted Connections...................................................................................................................... C6

E3.1 Shear, Spacing and Edge Distance................................................................................. C7E3.2 Fracture in Net Section (Shear Lag) ............................................................................... C8E3.4 Shear and Tension in Bolts.............................................................................................. C9

E4.3.2 Connection Shear Limited by End Distance................................................ C13E5 Rupture ....................................................................................................................................... C13

E5.1 Shear Rupture ................................................................................................................. C13E5.2 Tension Rupture............................................................................................................. C13E5.3 Block Shear Rupture ...................................................................................................... C13


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North American Specification for Design of Cold-Formed Steel

Roger L. Brockenbrough1and Helen H. Chen2

Abstract

For over fifty years, the American Iron and Steel Institute has published thewidely used Specification for the Design of Cold-Formed Steel Structural Members.Recently, as a result of collaborative efforts with representatives of Canada andMexico, the AISI Specificationwas expanded into a new document for use in allthree countries. Now known as the North American Specification for the Design ofCold-Formed Steel Structural Members, the new edition supersedes the previousAISI Specification and the Canadian S136 Standard. This paper reviews thedifferences between the previous AISI Specificationand the new North AmericanSpecification. The basic core document consists of Chapters A through G, while

country specific issues are addressed in three separate appendices. Theappendices include items of a broad nature, such as provisions for the designmethod to be used, the reference source for loads and load combinations, andother references that are country specific. The appendices also include countryspecific technical provisions where full agreement between the three countrieswas not reached. Efforts will be made to minimize these differences in futureeditions.

Introduction

The premier edition of the 2001 North American Specification for the Design of Cold-Formed Steel Structural Members(AISI, 2001), as its name implies, is intended foruse throughout Canada, Mexico and the United States. It supersedes theprevious editions of the Specification for the Design of Cold-Formed Steel StructuralMembers, published by the American Iron and Steel Institute (AISI, 1996 andAISI, 1999) for over 50 years, and the S136 Standard for Cold Formed SteelStructural Memberspublished by the Canadian Standards Association (CSA, 1994)for many years. This paper summarizes the technical changes between the NorthAmerican Specification and the 1996 AISI Specificationwith the 1999 Supplement.Research that led to many of these changes is referenced in the Commentaryto theNorth American Specification.

1President, R. L. Brockenbrough & Assoc., Inc., Pittsburgh, Pa., USA and Chairman of the AISI

Committee on Specifications for the Design of Cold-Formed Steel Structural Members2Senior Structural Engineer, AISI, Washington, DC, USA


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Background

The North American Specification is the result of a collaborative effort of theAmerican Iron and Steel Institute Committee on Specifications, the Canadian

Standard Association S136 Committee on Specifications, and Camara Nacionalde la Industria del Hiero y del Acero (CANACERO) in Mexico. The developmentof the Specificationwas coordinated through the North American SpecificationsCommittee, which contained three members each representing AISIs Committeeon Specifications, CSAs S136 Committee, and Mexicos CANACERO. Thecommittee typically met twice a year beginning in 1995. The then current AISISpecifications were used as the core document to work from. New or revisedprovisions were integrated therein over the last several years to meet therequirements of all three countries, which approved the final consensusdocument.

Specification Format

Since the Specification is intended for use in Canada, Mexico and the UnitedStates, it was necessary to develop a format that would facilitate the allowance ofunique requirements in each country. This resulted in a format that contained abasic document, Chapters A through G, intended for use in all three countries,and three country specific appendices, A through C. The appendices includeitems of a broad nature, such as provisions for the design method to be used, thereference source for loads and load combinations, and other references that arecountry specific. The appendices also include country specific technicalprovisions where full agreement between the three countries was not reached.Efforts will be made to minimize these differences in future editions.

This Specificationprovides an integrated treatment of Allowable Strength Design(ASD), Load and Resistance Factor Design (LRFD), and Limit States Design

(LSD). This is accomplished by including the appropriate resistance factors ()

for use with LRFD and LSD and the appropriate factors of safety () for use withASD.

Summary of Global Changes

1. Applicability. The Specification was expanded to apply to Canada andMexico as well as the United States. Most technical provisions wereadopted as common to the three countries. Others that are country specificwere grouped in lettered Appendices that apply only to a specific country:Appendix A United States, Appendix B Canada, and Appendix C Mexico.


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2. Design Methods. Three design methods are recognized: ASD now

termed Allowable Strength Design, LRFD Load and Resistance FactorDesign, and LSD Limit States Design. The use of ASD and LRFD islimited to the US and Mexico; LSD is limited to Canada. LRFD and LSD

are essentially the same except for differences in nomenclature, loadfactors, load combinations, and target reliability indexes. Equivalent LSDterminology is shown in brackets throughout the Specification. Sincedifferent target reliabilities are used in the US and Canada, the resistancefactors applicable to the US and Mexico differ from the ones for Canadathroughout the Specification.

3. Units. Although most of the Specification provisions are presented indimensionless form, three systems of units are shown where this was notpossible: US customary (kilo-pound, inch), SI (Newton, mm), and MKS

(kg, cm), which is used in Mexico.

4. Fatigue. Chapter G was added to provide for the design of members andconnections subjected to cyclic loading (fatigue).

Summary of Technical Changes

1. A1.1 Scope. For configurations where it is not possible to calculate thestrength or stiffness of members and connections from the provisions ofChapters B through G, the designer now has two options: (1.) Tests in

accordance with Chapter F or (2.) Rational engineering analysis. A set ofsafety factors and resistance factors for members and connections is givenfor use with rational analysis.

2. A1.2 Terms. The terminology was updated and expanded.

3. A2.1 Applicable Steels. References to ASTM specifications were updated.

4. A3 Loads. These provisions are given in country specific provisions. Forthe US, the provisions defer loads and load combinations to the applicablebuilding code or ASCE 7, and no load combinations are given in thedocument. Also, in A4.1.2, the use of the 0.75 factor on load combinationsfor ASD is limited to the combined effect of two or more loads, excludingdead load. This has the effect of eliminating the traditional 1/3 allowablestress increase on load combinations that include wind. Specific designrequirements for ponding were deleted as they are covered by thebuilding codes.


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5. B2.1 Uniformly Compressed Stiffened Elements. In determining effective

width, the slenderness factor was expressed in terms of the elastic

critical buckling stress Fcras = crFf/

6. B2.3 Webs and Other Stiffened Elements Under Stress Gradient.Different expressions are now given for determining the plate bucklingcoefficient k depending on the value of ho/bo, where ho is the out-to-outweb dimension and bois the out-to-out width of the compression flange.The expressions previously used were based on the assumption that theflanges restrained the web, but it was determined that this isunconservative when ho/bo> 4. Therefore, new expressions were addedfor the case where ho/bo> 4 and the previous equations retained for the

case where ho/bo4. Also, the stress ratio is now defined as an absolutevalue, so some of the signs in the equations have changed.

7. B4.1 Uniformly Compressed Elements with One Intermediate Stiffener.The expression for k was revised to eliminate a discontinuity in theprevious expressions.

8. B4.2 Uniformly Compressed Elements with an Edge Stiffener. Theexpressions for kwere revised to eliminate a discontinuity in the previousexpressions.

9. B5 Effective Widths of Stiffened Elements with Multiple IntermediateStiffeners or Edge Stiffened Elements with Intermediate Stiffeners. Based

on the results of new research, this section was completely rewritten andexpanded to include both Stiffened Elements with Multiple IntermediateStiffeners and Edge Stiffened Elements with Intermediate Stiffeners.Stiffened Elements with Multiple Intermediate Stiffeners covers both ageneral case (arbitrary stiffener size, location and number) and a specificcase for n identical stiffeners, equally spaced. In the approach adopted, kis determined as the lesser of the value calculated for both local buckling,in which the stiffener does not move, and distortional buckling, in whichthe stiffener buckles with the entire plate.

10. C2 Tension Members. The provisions for tension members are given in theappendices. For the U.S., the nominal tensile strength is taken as thesmallest value for the limit states of (a) yielding in the gross section, (b)fracture in the net section away from connections (not previouslyincluded), and (c) fracture in the effective net section at the connection,which is treated by reference to Chapter E.


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11. C3.2.1 Shear Strength of Webs Without Holes. The coefficients in theequations were changed slightly after recalibration. A single value wasadopted for the safety factor and the resistance factor, instead of differentvalues in different web slenderness ranges as in the past.

12. C3.4.1 Web Crippling Strength of Webs without Holes. In the previousSpecification, separate equations were given for the web crippling strengthunder different conditions. In the new Specification, as a result ofadditional research, a single consistent unified equation was adopted forthe web crippling strength under all conditions.

13. C3.5 Combined Bending and Web Crippling Strength. In the ASDinteraction equation for the support point of two nested Z-shapes, thecoefficients were slightly revised as a result of the changes made in theweb crippling equation.

14. C3.6 Stiffeners. This section was previously located in B6.

15. C4.3 Point-Symmetric Sections. A new section was added to indicate howthe elastic buckling stress should be determined for point-symmetricsections.

16. C4.5 Built-Up Members. This section was added to provide a generalmeans of calculating the axial compressive strength of two sections incontact. It replaces a previous section (D1.1a). An equation is given for

calculating a modified slenderness ratio, an approach that is used in AISCspecifications and others.

17. C5.2 Combined Compressive Axial Load and Bending. For singly-symmetric unstiffened angles with unreduced effective area, thecombined compressive and bending check does not need to consider theadditional moment PL/1000 as required in the previous editions. Thisrequirement is, however, still needed for other angle sections.

18. D3.2.2 Neither Flange Connected to Sheathing. This section specifies theforce for which intermediate braces for C- and Z-sections must bedesigned. A correction was made in the expression for Z-section bracing.

19. E2 Welded Connections. The factors of safety for welded connectiondesign were recalibrated to agree with the resistance factors.

20. E3.2 Tension Member Shear Lag Effect in Bolted Members. Theseprovisions are given in the appendices. For the U.S., the equations for the


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fracture stress on the net section were revised to reflect the results ofadditional research. Eqs. E3.2-2 and E3.2-4, which consider the strengthreduction due to out-of-plane deformation, are limited to connectionswith a single row of bolts perpendicular to the force.

21. E3.3.1 Strength Without Consideration of Bolt Hole Deformation. Theequation for bearing strength was revised to reflect the results ofadditional research.

22. E4.2 Minimum Edge and End Distance. For screw connections, theminimum distance from the center of a fastener to the edge of any partwas reduced from 3 diameters to 1.5 diameters. However, if the enddistance is parallel to the force, the shear strength per screw is subject to astrength reduction.

23. E4.3.3 Shear in Screws. The nominal shear strength was limited to 0.80times that reported by the manufacturer.

24. E4.4.3 Tension in Screws. The nominal tension strength was limited to 0.80times that reported by the manufacturer.

Conclusions

The development of the North American Specification for the Design of Cold-FormedSteel Structural Members provides a unified document that can be usedthroughout Canada, Mexico, and the United States. Even though there were a

few areas where full agreement between the three countries was not reached, thepublication of this document is a notable achievement, made possible only by thecontinuing spirit of cooperation among representatives of the three countries.Efforts will be made in future editions to minimize the remaining technicaldifferences.

Acknowledgements

The consensus committees responsible for developing these provisions provide abalanced forum including representatives from steel producers, fabricators,users, educators, researchers, and building code officials. They are composed of

engineers with a wide range of experience and high professional standing fromCanada, Mexico, and the United States. The continuing dedication by themembers of the specifications committees and their subcommittees is gratefullyacknowledged. The efforts of Reinhold M. Schuster, Chairman of the NorthAmerican Specifications Committee, in facilitating a consensus betweenrepresentatives of the three countries, are especially appreciated.


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References

American Iron and Steel Institute (2001), North American Specification for theDesign of Cold-Formed Steel Structural Members, Washington, D.C., 2001.

American Iron and Steel Institute (1996), Specification for the Design of Cold-FormedSteel Structural Members, Washington, D.C., 1996.

American Iron and Steel Institute (1999), Supplement No. 1 to the Specification forthe Design of Cold-Formed Steel Structural Members, Washington, D.C., 1999.

Canadian Standards Association (1994), S136 - Specification for Cold Formed SteelStructural Members,Toronto, Ontario, Canada, 1994.


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CCFSS Technical Bulletin

Vol. 11, No. 1 February 20

SUMMARY OF MAJOR CHANGES AND IMPROVEMENTSIN THE 2001 NORTH AMERICAN SPECIFICATION

FOR THE DESIGN OF COLD-FORMED STEEL STRUCTURAL MEMBERS

The 2001 edition of theNorth American Specification for the Design of Cold-Formed Steel Structural

Members will soon be issued in Canada, Mexico and the United States. This first edition of the North

American Specification was developed on the basis of the 1996 AISI Specification with the 1999 Supplement,

the 1994 Canadian Standards Association (CSA) Standard S136, and subsequent developments. It includes

a main document applicable to all three countries with Appendix A for US, Appendix B for Canada and

Appendix C for Mexico. A hand point symbol with appendix letters A, B and C is used in the main document

to point out that additional provisions are provided in the corresponding applications.

Three design methods (ASD, LRFD, and LSD) were included in this new North American

Specification. ASD and LRFD methods are used only in the US and Mexico, and LSD is used only in

Canada. The equivalent terms for LSD were included in the brackets for the convenience of LSD users.

The factors of safety and resistance factors were listed in the corresponding design provisions.

This Technical Bulletin presents a brief summary of major changes made in the North American

Specification as compared with the 1996 AISI Specification with the 1999 Supplement. All section numbers

shown below are those used in the North American Specification. The reasoning behind and the justification

for the revisions and additions are discussed in the Commentary on the North American Specification.

A. General Provisions

A1.1 Scope and Limits of Applicability

This Section was completely revised except for the first paragraph. It specifies that the

Allowable Strength Design (ASD) and Load and Resistance Factor Design (LRFD) methods

are used in the United States and Mexico, while the Limit Sates Design (LSD) method is

used in Canada according to Chapters A through G, and Appendices A through C for a

specific country. For those special cases where the design strength and/or stiffness cannot

be so determined, it can be established either by tests or by rational engineering analysis on

the basis of the given factor of safety and resistance factor.

A1.2 Terms

This Section was revised to include General Terms, ASD and LRFD Terms (USA and

Mexico), and LSD Terms (Canada).

A1.3 Units of Symbols and Terms

This Section was revised to use U.S. customary units, SI units, and MKS units.


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CCFSS Tech Bulletin February 2002

(Section A2, Non-Conforming Shapes and Construction, of the 1996 AISI Specification

was deleted in the North American Specification.)

A2.1 Applicable Steels

The Section number was changed from A3.1 to A2.1. The ASTM A1008 and A1011 Standards

in the North American Specification replaced the ASTM A570, A607, A611, and A715Standards in the 1996 AISI Specification and the 1999 Supplement. ASTM A1003 Standard

was added to the list of Section A2.1.

A2.2 Other Steels

The Section number was changed from A3.2 to A2.2. Editorial changes were made in the

text for section numbers. This section was moved to Appendix A for use in the United

States.

A2.3 Ductility

The Section number was changed from A3.3 to A2.3. Editorial revisions were made for the

use of the LSD method and the MKS unit. The ASTM Standards were updated according tothe revisions of Section A2.1.

A2.4 Delivered Minimum Thickness

The Section number was changed from A3.4 to A2.4.

A3 Loads

The Section number was changed from A4 to A3. The design requirements for loads and

load combinations are presented in Section A3 of Appendix A for use in the United States.

The definitions of symbols were deleted. Section A4.2 of the 1996 AISI Specification for

ponding was deleted.

A4 Allowable Strength Design

The Section number was changed from A5 to A4 with a title change from Allowable Stress

Design to Allowable Strength Design.

A4.1 Design Basis

The Section number was changed from A5.1 to A4.1. The term Allowable Stress Design

was changed to Allowable Strength Design. Other editorial revisions were also made in

this Section.

A4.1.1 ASD RequirementsThe Section number was changed from A5.1.1 to A4.1.1 with a title change from ASD

Strength Requirements to ASD Requirements.

A4.1.2 Load Combinations for ASD

This Section was completely rewritten by deferring loads and load combinations to applicable

building codes and ASCE 7. It replaces the design requirements previously covered in Sections

A5.1.2, A5.1.3 and A5.1.4 of the 1996 AISI Specification. This newly revised Section A4.1.2

is included in Appendix A for use in the United States.


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February 2002 CCFSS Tech Bulleti

A5 Load and Resistance Factor Design

The Section number was changed from A6 to A5.

A5.1 Design Basis

The Section number was changed from A6.1 to A5.1. Editorial revisions were also made in

this section.

A5.1.1 LRFD Requirements

The Section number was changed from A6.1.1 to A5.1.1 with a title change from LRFD

Strength Requirements to LRFD Requirements.

A5.1.2 Load Factors and Load Combinations for LRFD

This Section was completely rewritten by deferring loads and load combinations to applicable

codes and ASCE 7. It replaces the design requirements previously covered in Sections A6.1.2

and A6.1.3 of the 1996 AISI Specification. It is included in Appendix A for use in the United

States.

A9 Referenced Documents

The first paragraph was revised with a reference to Appendix A for documents applicable to

the United States. ASCE 7, AISC ASD Specification, AISC LRFD Specification, AWS D1.3

98, AWS C1.1-66, and AWS C1.3-70 Standards were moved to Section A9a of Appendix A

ASME B46.1-85 was added. All ASTM standards were updated. ASTM A1008 and A101

Standards replaced the ASTM A570, A607, A611, and A715 Standards. ASTM A1003

Standard was added to the list.

B. ELEMENTS

B1.1(a) Maximum Flat-Width-to-Thickness Ratios

In Item (1), definitions of Is and Iawere added.

B1.1(b) Flange Curling

The footnote for flange curling was changed to a note in the text.

B2 Effective Widths of Stiffened Elements

In this Section, the term Load Capacity Determination was changed to Strength

Determination, and the term Deflection Determination was changed to Serviceability

Determination.

B2.1 Uniformly Compressed Stiffened Elements

Equation E2.1-4 for computing the slenderness factor was changed with an addition o

Equation E2.1-5 for Fcr. Minor editorial revision was made for the definition of f.

B2.3 Webs and other Stiffened Elements under Stress Gradient

A list of symbols and definitions were added to the first paragraph of this Section. The design

requirements were revised to adopt a two-part approach for the effective width of webs based

on the ratio of overall web width to overall flange width. The stress ratio is defined as an


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absolute value and some signs for were changed in several related equations.

B2.4 C-Section Webs with Holes under Stress Gradient

Condition do /h < 0.7 was revised to do /h 0.7.

B3 Effective Widths of Unstiffened ElementsIn this Section, the term Load Capacity Determination was changed to Strength

Determination, and the term Deflection Determination was changed to Serviceability

Determination.

B4 Effective Widths of Elements with One Intermediate Stiffener or an Edge Stiffener

In this Section, the term Deflection Determination was changed to Serviceability

Determination.

B4.1 Uniformly Compressed Elements with One Intermediate Stiffener

The design requirements for the case of bo/ t > Swere changed to eliminate the discontinuity.

A new equation (Eq. B4.1-4) for determining n was added.

B4.2 Uniformly Compressed Elements with an Edge Stiffener

The limiting w/twas changed from S/3 to 0.328S. Design equations were changed for the

case of w/t> 0.328Sby adopting an equation for n, which eliminated a discontinuity that

existed in the previous design expressions.

B5 Effective Widths of Stiffened Elements with Multiple Intermediate Stiffeners or Edge

Stiffened Elements with Intermediate Stiffeners

This Section was completely revised to reflect recent research findings for flexural members

with intermediate stiffeners in the compression flange. It includes two new subsections tocover sub-element local buckling and distortional buckling. Section B5.1 deals with the

effective widths of uniformly compressed stiffened elements with multiple intermediate

stiffeners, while Section B5.2 deals with edge stiffened elements with intermediate stiffeners.

(Section B6 Stiffeners of the 1996 AISI Specification was changed to Section C3.6 of the

North American Specification. See Chapter C on Members)

C. MEMBERS

C2 Tension Members

This Section was moved to Appendix A for use in the United States.

C3.1 Bending

The title of this Section was simplified. In the first paragraph, reference is made to Appendix

A for use in the United States. The footnote for torsional effects was added as the second

paragraph of this Section.

C3.1.1 Nominal Section Strength [Resistance]

In Subsection (b) for Procedure II, Condition (4) was revised to read The shear force does


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not exceed 0.35 Fytimes the web area, ht, for ASD, and 0.60 Fyht for LRFD.

The footnote for the applicability of design provisions was added as the first paragraph of this

Section.

In Subsection (a), Cb and CTF are not required to be unity (1.0) for members subject to combinedaxial load and bending moment in the North American Specification.

In Subsection (b), Eq. C3.1.2.1-14 is now permitted for doubly-symmetric I-sections and

singly-symmetric C-sections. The unbraced length L in Eqs. C3.1, 2.1-14 and C3.1.2-15

was clarified as Ly.

C3.1.2.2

The unbraced length L in Eq.C3.1.2.2-2 was clarified as Ly.

C3.1.4 Beams Having One Flange Fastened to a Standing Seam Roof System


C3.1.5 Strength [Resistance] of Standing Seam Roof Panel Systems

In the last line of this Section, the resistance factor was revised from 0.5 to 0.8 for the

number of physical test assemblies less than 3.

C3.2 Shear

The title of this Section was simplified.

C3.2.1 Shear Strength [Resistance] of Webs without Holes

The format for the nominal shear strength was revised to be Vn = AwFv. Equations are given

for Fvgoverned by shear yielding, inelastic shear buckling and elastic shear buckling. Thefactor of safety for ASD was revised to 1.60 and the resistance factor for LRFD was changed

to 0.95 for all cases.

C3.2.2 Shear Strength [Resistance] of C-Section Webs with Holes

Condition do/h < 0.7 was revised to do/h 0.7

C3.3.1 ASD Method

For beams with unreinforced webs, the design provisions were revised to specify that the

required allowable flexural strength,M, and the required allowable shear strength, V, shall not

exceedMn/b and Vn/ v, respectively.

C3.3.2 LRFD and LSD Methods

For beams with unreinforced webs, the design provisions were revised to specify that the

required flexural strength [factored moment],Mu, and the required shear strength [factored

shear], Vu , shall not exceed bMnand vVn, respectively.

C3.4 Web Crippling

The title of this Section was simplified. This Section was completely revised to use a unified

web crippling strength equation with variable coefficients on the basis of the type of cross

Lateral-Torsional Buckling Strength [Resistance]of Closed Box Members

C3.2.1 Lateral-Torsional Buckling Strength [Resistance] of Open Cross Section Members


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section and the fastened condition at support. The web crippling coefficients, factors

of safety for ASD, and resistance factors for LRFD are presented in five separate

tables for built-up sections, single web channel and C-sections, single web Z-

sections, single hat sections, and multi-web deck sections, either fastened or

unfastened to support.

C3.5.1 ASD Method

In Subsection (c), the interaction equation for the support point of two nested Z-

sections was modified according to the new web crippling equation. In addition, it

is specified that the moment,M, and the concentrated load or reaction, P, shall not

exceedMno/ band P n/w, respectively.

C3.5.2LRFD and LSD Methods

In subsection (c), the interaction equation for two nested Z-shapes was modified

according to the new web crippling equation. In addition, it is specified that the

moment,Mu, and the concentrated load or reaction, Pu, shall not exceed bMno and

wP n, respectively, for the LRFD method.

C3.6 Stiffeners

This Section was previously included in Chapter B of the 1996 AISI Specification

as Section B6. It was moved to Section C3.6 for the design of flexural members.

C3.6.3Non-Conforming Stiffeners

This Section was revised to permit the use of rational engineering analysis with

some minor changes on section numbers.

C4.1 Sections Not Subject to Torsional or Torsional-Flexural BucklingThe footnote for the effective length factor was moved to the text as a new note.

C4.2 Doubly or Singly-Symmetric Sections Subject to Torsional or Torsional-Flexural

Buckling

A new paragraph was added at the end of this Section for singly-symmetric

unstiffened angle sections, for which the effective area (Ae) at stress Fyis equal to

the full unreduced cross-sectional area (A).

C4.3 Point-Symmetric Sections

This is a new Section for the design of point-symmetric sections.

C4.4 Nonsymmetric Sections

This Section was renumbered from C4.3 in the 1996 AISI Specification to C4.4

in the North American Specification.

C4.5 Built-Up Members

This is a new Section for built-up members. It replaces Section D1.1(a) of the 1996

AISI Specification.


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C4.6 Compression Members Having One Flange Through-Fastened to Deck or Sheathing

This Section was renumbered from Section C4.4 of the 1996 AISI Specification to Section

C4.6 of the North American Specification. Minor revisions were made in conditions (5),

(6), and (8). The footnote for Condition (8) in the 1996 AISI Specification was added to the

text as a new Note.

C5.2.1ASD Method

In the first paragraph, an additional requirement was added to specify that each individual

ratio in Eqs. C5.2.1-1 and C5.2.1-3 shall not exceed unity.

For the definition of My , the design requirements for singly-symmetric unstiffened angle

sections were revised in the North American Specification.

C5.2.2 LRFD and LSD Methods

In the first paragraph, an additional requirement was added to specify that each individual

ratio in Eqs. C5.2.2-1 and C5.2.2-3 shall not exceed unity.

For the definition ofMuy , the design requirements for singly-symmetric unstiffened angle

sections were revised in the North American Specification.

C6 Closed Cylindrical Tubular Members

The term Cylindrical Tubular Members was changed to Closed Cylindrical Tubular

Members in the title and the text.

C6.1 Bending

Definitions of D and t were added.

C6.2 Compression

Equation C6.2-5 for determining Ae was simplified with the revision of Eq. C6.2-6 fordetermining R. Definitions of D and t were added.

D. Structural Assemblies

D1.1 I-Sections Composed of Two C-Sections

In Subsection (a), new requirements for built-up compression members composed of two

C-sections are given in Section C4.5.

In Subsection (b), the equations for determining m (Eqs. D1.1-3 and D1.1-4 of the 1996

AISI Specification) and the definitions of wf,d,D, andIxwere moved to the Commentary.

D3.2 C-Section and Z-Section BeamsThe footnote in the 1996 AISI Specification was added to the text as a new Note.

D3.2.2 Neither Flange Connected to Sheathing

The equation for determining K for Z-sections (Eq. D3.2.2-2) was revised from

K= Ixy/ Ix to K=Ixy/2Ix. The direction of the applied brace force for Z-sections is

also specified in the new requirement.

Other editorial changes were also made in the text.


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D4 Wall Studs and Wall Stud Assemblies

Minor editorial changes were made in the text. The limits for yield strength, section depth,

section thickness, overall length, and stud spacing previously included in Subsection (b)

were moved to Section D4.1.

D4.1 CompressionThe title of this Section as simplified. Limits for using the equations provided in Conditions

(a), (b), and (c) of this Section were added from Section D4. Editorial revisions were made

for several symbols not previously defined in this Section.

D4.2 Bending

The title of this Section was simplified. The definitions ofMnxoand Mnyowere revised to

directly refer to Section C3.1.1.

E. Connections and Joints

E2 Welded Connections

This Section was revised by moving some of the design provisions to Section E2a of

Appendix A for use in the United States.

E2.1 Groove Welds in Butt Joints

For the ASD method, the factors of safety for tension, compression, and shear were reduced.

E2.2 Arc Spot Welds

All figures in the Specification use numbers at the end instead of letters

E2.2.1 ShearSome factors of safety for ASD and resistance factors for LRFD were revised for Subsections

(a) and (b).

The definition of da for multiple sheets not more than four lapped sheets over a supporting

member was changed from (d - 2t)to (d - t).

For the ASD method, the factors of safety for Eq. E2.2.1-6a were revised.

Minor editorial revisions were also made.

E2.2.2 Tension

In the North American Specification, Eq. E2.2.2-2 was modified to replace Eqs. E2.2.2-2

and E2.2.23 of the 1996 AISI Specification. Different factors of safety and resistance

factor are used for applications other than panels and decks. A new limitation for the valueof tda Fuwas added.

E2.3 Arc Seam Welds

For the ASD method, the factor of safety was increased slightly. The definition of da was

revised for a double sheet in the North American Specification. All figures in the

Specification use numbers at the end instead of letters.

E2.4 Fillet Welds


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Several factors of safety and resistance factors were revised. This Section was revised to

require a weld strength check when the plate thickness is greater than 0.10 in. i.e., the thickness

limit of t > 0.15 in. was changed to t > 0.10 in. All figures in the Specification use numbers

at the end instead of letters.

E2.5 Flare Groove WeldsSeveral factors of safety and one resistance factor were revised. All figures in the Specification

use numbers at the end instead of letters. Thickness limit for weld strength check was revised

to t> 0.10 in.

E2.6 Resistance Welds

For the ASD method, the factor of safety was increased slightly. Equations E2.6-5 and E2.6-

6 for the MKS unit were added.

E2.7 Fracture in Net Section of Members Other Than Flat Sheets (Shear Lag)

The title of this Section was changed from Shear Lag Effect in Welded Connections of

Members Other Than Flat Sheets.

E3 Bolted Connections

The design provisions for the thickness of the thinnest connected part exceeding 3/16 in., the

maximum size of holes and other requirements were moved to Section E3a of Appendix A for

use in the United States.

E3.1 Shear, Spacing and Edge Distance

This Section was moved to Appendix A for use in the United States. Minor editorial revisions

were made for spacing and edge distance.

E3.2 Fracture in Net Section (Shear Lag)

This Section was moved to Appendix A for use in the United States. The title of this Section

was changed from Shear Lag Effect in Bolted Connections.

In Subsection (1), the design provisions were revised to use the reduction equation of Ftonly

for a single bolt or a single row of bolts perpendicular to the force. For multiple bolts in the

line parallel to the force, Ft = Fu. The definition of r was deleted and the definition of s

was revised.

In Subsection (2), the design provisions were simplified.

E3.3 Bearing

This Section was revised by including two subsections: E3.3.1 Strength without Considerationof Bolt Hole Deformation and E3.3.2 Strength with Consideration of Bolt Hole Deformation.

In Section E3.3.1, the design format and tables for determining the bearing strength were

revised on the basis of the bearing factor, modification factor, and the ratio of bolt diameter to

member thickness, d/t.The factor of safety and resistance factor were also revised accordingly.

A variable was introduced in Eq. E3.3.2-1 to accommodate different units used.

E3.4 Shear and Tension in Bolts



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E4 Screw Connections

Editorial revisions were made in this Section. Definitions of new terms were added for dw,

Pss, Ptxand tc .

E4.2 Minimum Edge and End Distances

The minimum distance from the center of a fastener to the edge of any part was revised from

3dto 1.5d. The nominal shear strength per screw is specified for the end distance parallel to

the force.

E4.3.1 Connection Shear Limited by Tilting and Bearing

The title of this Section was revised from Connection Shear.

E4.3.2 Connection Shear Limited by End Distance

This Section was completely revised. It was moved to Appendix A for use in the United

States.

E4.4 Tension

The sentence and shall be determined according to Section F1 was deleted.

E4.4.1 Pull-Out

The definition of tcwas deleted.

E4.4.2 Pull-Over

Editorial revision was made for the definition of dw.

E4.4.3 Tension in Screws

This Section was revised by adding a new equation for calculating the nominal tensile strengthfor screws.

E5 Rupture

The entire section including Subsections E5.1, E5.2, and E5.3 were moved to Appendix A

for use in the United States.

F1.1 Load and Resistance Factor Design and Limit States Design

Editorial revisions were made in the first paragraph with the update of several section numbers

in the text.

The footnote in the 1996 AISI Specification was added to the text as a Note.

F3.1 Full Section

Item (d) of this Section was revised to require one full section test be made from each master

coil for acceptance and control purposes.

F3.3 Virgin Steel

Minor editorial revisions were made in this Section.


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F. Design of Cold-Formed Steel Structural Members and Connections for Cyclic Loading

(Fatigue)

This is a new chapter for fatigue design. It was developed on the basis of the available research

data on cold-formed steel members and the AISC provisions.

Appendix A: Provisions Applicable to the United States

This is a new Appendix. It contains Sections A1.1a, A2.2, A3.1, A4.1.2, A5.1.2, C2, C3.1.4, E2a,

E3a, E3.1, E3.2, E3.4, E4.3.2, and E5, which are applicable only to the United States.

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