LOAD AND RESISTANCE FACTOR DESIGN SPECIFICATION

FACTOR DESIGN SPECIFICATION

For Structural Steel Buildings

December 27, 1999

Load and Resistance Factor Design Specification for Structural Steel Buildings

December 27, 1999

with errata incorporated as of September 4, 2001

Supersedes the Load and Resistance Factor Design Specification for Structural Steel Buildings dated December 1, 1993 and all previous versions.

Prepared by the American Institute of Steel Construction, Inc. Under the Direction of the AISC Committee on Specifications and approved by the AISC Board of Directors.

AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.

One East Wacker Drive, Suite 3100 Chicago, Illinois 60601-2001 One East Wacker Drive, Suite 3100 Chicago, Illinois 60601-2001

Copyright © 2000 by American Institute of Steel Construction, Inc.

All rights reserved. This book or any part thereof must not be reproduced in any form without the written permission of the publisher.

The information presented in this publication has been prepared in accordance with recognized engineering principles and is for general information only. While it is believed to be accurate, this information should not be used or relied upon for any specific application without competent professional examination and verification of its accuracy, suitability, and applicability by a licensed engineer, architect or other professional. The publication of the material contained herein is not intended as a representation or warranty on the part of the American Institute of Steel Construc- tion, Inc. or of any other person named herein, that this information is suitable for any general or particular use or of freedom from infringement of any patent or pat- ents. Anyone making use of this information assumes all liability arising from such use.

Caution must be exercised when relying upon other specifications and codes devel- oped by other bodies and incorporated by reference herein since such material may

be modified or amended from time to time subsequent to the printing of this edition. The American Institute of Steel Construction, Inc. bears no responsibility for such material other than to refer to it and incorporate it by reference at the time of the initial publication of this edition.

Printed in the United States of America Printed in the United States of America

PREFACE

The AISC Load and Resistance Factor Design (LRFD) Specification for Structural Steel Buildings is based on reliability theory. As have all AISC Specifications, this Specifica- tion has been based upon past successful usage, advances in the state of knowledge, and changes in design practice. This Specification has been developed as a consensus docu- ment to provide a uniform practice in the design of steel-framed buildings. The intention is to provide design criteria for routine use and not to provide specific criteria for infre- quently encountered problems, which occur in the full range of structural design.

This Specification is the result of the consensus deliberations of a committee of structural engineers with wide experience and high professional standing, representing a wide geo- graphical distribution throughout the U.S. The committee includes approximately equal numbers of engineers in private practice and code agencies, engineers involved in research and teaching, and engineers employed by steel fabricating and producing com- panies. The contributions and assistance of more than 50 additional professional volun- teers working in 15 task committees are also hereby acknowledged.

The Symbols, Glossary, and Appendices to this Specification are an integral part of the Specification. A non-mandatory Commentary has been prepared to provide background for the Specification provisions and the user is encouraged to consult it.

The principal changes incorporated in this edition of the Specification include:

• Dual units format. Values and equations are given in both U.S. customary and metric units. The metric conversions (given in parentheses following the U.S. units) are based on ASTM E380, Standard Practice for Use of the International System of Units (SI) . The equations are non-dimensionalized where possible by factoring out material constants, such as E and G.

• Inclusion of new structural steels ASTM A913 and A992. • Additional notch toughness requirements for complete-joint-penetration

groove welds with tension applied normal to the effective area. • New provisions for stability bracing of beams, columns, and frames. • New Chapter N for evaluation of existing structures. • Revised provisions for member design under fatigue loading in Appendix

K.

iv

PREFACE

• Reorganization of material on pin-connected members and eyebars. • Revised provisions for concrete-encased beams. • New limitation on the stud reduction factor when a single stud is used in a

rib. • Revised bolt bearing strength criteria.

The reader is cautioned that professional judgment must be exercised when data or recom- mendations in the Specification are applied, as described more fully in the disclaimer notice preceding this Preface.

By the Committee, Stanley D. Lindsey, Chairman

Nestor R. Iwankiw

Roger E. Ferch, Vice Chairman

Lawrence A. Kloiber

Hansraj G. Ashar

Roberto T. Leon

William F. Baker

H.S. Lew

John M. Barsom

James O. Malley

Reidar Bjorhovde

Richard W. Marshall

Roger L. Brockenbrough

Harry W. Martin

Wai-Fah Chen

William A. Milek

Gregory G. Deierlein

Duane K. Miller

Robert O. Disque

Thomas M. Murray

Duane S. Ellifritt

R. Shankar Nair

Bruce R. Ellingwood

Clarkson W. Pinkham

Shu-Jin Fang

Douglas D. Rees-Evans

Steven J. Fenves

Thomas Z. Scarangello

James M. Fisher

Donald R. Sherman

John W. Fisher

W. Lee Shoemaker

Theodore V. Galambos

Frank F. Sowokinos

Lawrence G. Griffis

William A. Thornton

James R. Harris

Raymond H. R. Tide

Tony C. Hazel

Ivan M. Viest

Mark V. Holland

Joseph A. Yura Cynthia J. Lanz, Secretary

TABLE OF CONTENTS

SYMBOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii

SPECIFICATION

A. GENERAL PROVISIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A2. Types of Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A3. Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1. Structural Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Steel Castings and Forgings . . . . . . . . . . . . . . . . . . . . . . 4

3. Bolts, Washers, and Nuts . . . . . . . . . . . . . . . . . . . . . . . . 4

4. Anchor Rods and Threaded Rods . . . . . . . . . . . . . . . . . . . 5

5. Filler Metal and Flux for Welding . . . . . . . . . . . . . . . . . . . 5

6. Stud Shear Connectors . . . . . . . . . . . . . . . . . . . . . . . . . 6 A4. Loads and Load Combinations . . . . . . . . . . . . . . . . . . . . . . . 6 A5. Design Basis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1. Required Strength at Factored Loads . . . . . . . . . . . . . . . . . . 6

2. Limit States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3. Design for Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4. Design for Serviceability and Other Considerations . . . . . . . . . . 7 A6. Referenced Codes and Standards . . . . . . . . . . . . . . . . . . . . . . 7 A7. Design Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

B. DESIGN REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . 10 B1. Gross Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 B2. Net Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 B3. Effective Area of Tension Members . . . . . . . . . . . . . . . . . . . . 10 B4. Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 B5. Local Buckling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1. Classification of Steel Sections . . . . . . . . . . . . . . . . . . . . 12

2. Design by Plastic Analysis . . . . . . . . . . . . . . . . . . . . . . 13

3. Slender-Element Compression Sections . . . . . . . . . . . . . . . 13 B6. Bracing at Supports . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 B7. Limiting Slenderness Ratios . . . . . . . . . . . . . . . . . . . . . . . . 13 B8. Simple Spans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 B9. End Restraint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

B10. Proportions of Beams and Girders . . . . . . . . . . . . . . . . . . . . . 13

C. FRAMES AND OTHER STRUCTURES . . . . . . . . . . . . . . . . . . . 17 C1. Second Order Effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1. Design by Plastic Analysis . . . . . . . . . . . . . . . . . . . . . . 17

2. Design by Elastic Analysis . . . . . . . . . . . . . . . . . . . . . . 17 C2. Frame Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1. Braced Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2. Unbraced Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2. Unbraced Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

TABLE OF CONTENTS

SPECIFICATION (Cont’d)

C3. Stability Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

D. TENSION MEMBERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 D1. Design Tensile Strength . . . . . . . . . . . . . . . . . . . . . . . . . . 24 D2. Built-Up Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 D3. Pin-Connected Members and Eyebars . . . . . . . . . . . . . . . . . . . 25

1. Pin-Connected Members . . . . . . . . . . . . . . . . . . . . . . . 25

2. Eyebars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

E. COLUMNS AND OTHER COMPRESSION MEMBERS. . . . . . . . . . 27 E1. Effective Length and Slenderness Limitations. . . . . . . . . . . . . . . 27

1. Effective Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2. Design by Plastic Analysis . . . . . . . . . . . . . . . . . . . . . . 27 E2. Design Compressive Strength for Flexural Buckling . . . . . . . . . . . 27 E3. Design Compressive Strength for Flexural-Torsional Buckling . . . . . . 28 E4. Built-Up Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

1. Design Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2. Detailing Requirements . . . . . . . . . . . . . . . . . . . . . . . . 29 E5. Connections for Pin-Connected Compression Members . . . . . . . . . . 30

F. BEAMS AND OTHER FLEXURAL MEMBERS . . . . . . . . . . . . . . 31 F1. Design for Flexure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

1. Yielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2. Lateral-Torsional Buckling . . . . . . . . . . . . . . . . . . . . . . 32

3. Design by Plastic Analysis . . . . . . . . . . . . . . . . . . . . . . 34 F2. Design for Shear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

1. Web Area Determination . . . . . . . . . . . . . . . . . . . . . . . 35

2. Design Shear Strength. . . . . . . . . . . . . . . . . . . . . . . . . 35

3. Transverse Stiffeners . . . . . . . . . . . . . . . . . . . . . . . . . 36 F3. Web-Tapered Members . . . . . . . . . . . . . . . . . . . . . . . . . . 36 F4. Beams and Girders with Web Openings . . . . . . . . . . . . . . . . . . 36

G. PLATE GIRDERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

H. MEMBERS UNDER COMBINED FORCES AND TORSION . . . . . . . 38 H1. Symmetric Members Subject to Bending and Axial Force . . . . . . . . 38

1. Doubly and Singly Symmetric Members in Flexure and Tension . . 38

2. Doubly and Singly Symmetric Members in Flexure and Compression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

H2. Unsymmetric Members and Members Under Torsion and Combined Torsion, Flexure, Shear, and/or Axial Force . . . . . . . . . . 39 H3. Alternative Interaction Equations for Members Under Combined Stress (see Appendix H3) . . . . . . . . . . . . . . . . . . . . . . . . . 39

I. COMPOSITE MEMBERS . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 I1. Design Assumptions and Definitions . . . . . . . . . . . . . . . . . . . 40 I2. Compression Members. . . . . . . . . . . . . . . . . . . . . . . . . . . 41

1. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

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SPECIFICATION (Cont’d)

2. Design Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

3. Columns with Multiple Steel Shapes . . . . . . . . . . . . . . . . . 42

4. Load Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 I3. Flexural Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

1. Effective Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

2. Design Strength of Beams with Shear Connectors . . . . . . . . . . 43

3. Design Strength of Concrete-Encased Beams . . . . . . . . . . . . 44

4. Strength During Construction . . . . . . . . . . . . . . . . . . . . . 44

5. Formed Steel Deck . . . . . . . . . . . . . . . . . . . . . . . . . . 44

6. Design Shear Strength. . . . . . . . . . . . . . . . . . . . . . . . . 46 I4. Combined Compression and Flexure . . . . . . . . . . . . . . . . . . . 46 I5. Shear Connectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

1. Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

2. Horizontal Shear Force . . . . . . . . . . . . . . . . . . . . . . . . 46

3. Strength of Stud Shear Connectors . . . . . . . . . . . . . . . . . . 47

4. Strength of Channel Shear Connectors . . . . . . . . . . . . . . . . 47

5. Required Number of Shear Connectors . . . . . . . . . . . . . . . . 47

6. Shear Connector Placement and Spacing . . . . . . . . . . . . . . . 48 I6. Special Cases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

J. CONNECTIONS, JOINTS, AND FASTENERS . . . . . . . . . . . . . . . 49 J1. General Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

1. Design Basis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

2. Simple Connections . . . . . . . . . . . . . . . . . . . . . . . . . 49

3. Moment Connections . . . . . . . . . . . . . . . . . . . . . . . . . 49

4. Compression Members with Bearing Joints . . . . . . . . . . . . . 49

5. Splices in Heavy Sections . . . . . . . . . . . . . . . . . . . . . . 49

6. Beam Copes and Weld Access Holes. . . . . . . . . . . . . . . . . 50

7. Minimum Strength of Connections . . . . . . . . . . . . . . . . . . 50

8. Placement of Welds and Bolts . . . . . . . . . . . . . . . . . . . . 51

9. Bolts in Combination with Welds . . . . . . . . . . . . . . . . . . 51

10. High-Strength Bolts in Combination with Rivets . . . . . . . . . . . 51

11. Limitations on Bolted and Welded Connections . . . . . . . . . . . 51 J2. Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

1. Groove Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

2. Fillet Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

3. Plug and Slot Welds . . . . . . . . . . . . . . . . . . . . . . . . . 56

4. Design Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

5. Combination of Welds. . . . . . . . . . . . . . . . . . . . . . . . . 58

6. Weld Metal Requirements . . . . . . . . . . . . . . . . . . . . . . 58

7. Mixed Weld Metal. . . . . . . . . . . . . . . . . . . . . . . . . . . 58

8. Preheat for Heavy Shapes . . . . . . . . . . . . . . . . . . . . . . . 58 J3. Bolts and Threaded Parts. . . . . . . . . . . . . . . . . . . . . . . . . . 58

1. High-Strength Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . 58

2. Size and Use of Holes . . . . . . . . . . . . . . . . . . . . . . . . 59

3. Minimum Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4. Minimum Edge Distance . . . . . . . . . . . . . . . . . . . . . . . 60

5. Maximum Spacing and Edge Distance . . . . . . . . . . . . . . . . 60

6. Design Tension or Shear Strength . . . . . . . . . . . . . . . . . . 62 6. Design Tension or Shear Strength . . . . . . . . . . . . . . . . . . 62

TABLE OF CONTENTS

SPECIFICATION (Cont’d)

7. Combined Tension and Shear in Bearing-Type Connections . . . . . 63

8. High-Strength Bolts in Slip-Critical Connections . . . . . . . . . . 64

9. Combined Tension and Shear in Slip-Critical Connections . . . . . 66

10. Bearing Strength at Bolt Holes . . . . . . . . . . . . . . . . . . . . 66

11. Long Grips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 J4. Design Rupture Strength . . . . . . . . . . . . . . . . . . . . . . . . . . 67

1. Shear Rupture Strength . . . . . . . . . . . . . . . . . . . . . . . . 67

2. Tension Rupture Strength. . . . . . . . . . . . . . . . . . . . . . . 67

3. Block Shear Rupture Strength. . . . . . . . . . . . . . . . . . . . . 67 J5. Connecting Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

1. Eccentric Connections. . . . . . . . . . . . . . . . . . . . . . . . . 68

2. Design Strength of Connecting Elements in Tension . . . . . . . . . 68

3. Other Connecting Elements . . . . . . . . . . . . . . . . . . . . . . 68 J6. Fillers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 J7. Splices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 J8. Bearing Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 J9. Column Bases and Bearing on Concrete. . . . . . . . . . . . . . . . . . 70 J10. Anchor Rods and Embedments . . . . . . . . . . . . . . . . . . . . . . 70

K. CONCENTRATED FORCES, PONDING, AND FATIGUE. . . . . . . . . 71 K1. Flanges and Webs with Concentrated Forces . . . . . . . . . . . . . . . 71

1. Design Basis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

2. Flange Local Bending . . . . . . . . . . . . . . . . . . . . . . . . 71

3. Web Local Yielding . . . . . . . . . . . . . . . . . . . . . . . . . . 72

4. Web Crippling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

5. Web Sidesway Buckling. . . . . . . . . . . . . . . . . . . . . . . . 73

6. Web Compression Buckling . . . . . . . . . . . . . . . . . . . . . 74

7. Web Panel-Zone Shear . . . . . . . . . . . . . . . . . . . . . . . . 75

8. Unframed Ends of Beams and Girders . . . . . . . . . . . . . . . . 76

9. Additional Stiffener Requirements for Concentrated Forces . . . . . 76

10. Additional Doubler Plate Requirements for Concentrated Forces . . 76 K2. Ponding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 K3. Design for Cyclic Loading (Fatigue). . . . . . . . . . . . . . . . . . . . 77

L. SERVICEABILITY DESIGN CONSIDERATIONS . . . . . . . . . . . . . 79 L1. Camber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 L2. Expansion and Contraction . . . . . . . . . . . . . . . . . . . . . . . . 79 L3. Deflections, Vibration, and Drift . . . . . . . . . . . . . . . . . . . . . 79

1. Deflections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

2. Floor Vibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

3. Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 L4. Connection Slip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 L5. Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

M. FABRICATION, ERECTION, AND QUALITY CONTROL . . . . . . . . 81 M1. Shop Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 M2. Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

1. Cambering, Curving, and Straightening . . . . . . . . . . . . . . . 81

2. Thermal Cutting . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

3. Planing of Edges . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

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ix

SPECIFICATION (Cont’d)

4. Welded Construction . . . . . . . . . . . . . . . . . . . . . . . . . 82

5. Bolted Construction . . . . . . . . . . . . . . . . . . . . . . . . . 82

6. Compression Joints . . . . . . . . . . . . . . . . . . . . . . . . . . 82

7. Dimensional Tolerances . . . . . . . . . . . . . . . . . . . . . . . . 82

8. Finish of Column Bases . . . . . . . . . . . . . . . . . . . . . . . . 82 M3. Shop Painting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

1. General Requirements . . . . . . . . . . . . . . . . . . . . . . . . 83

2. Inaccessible Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . 83

3. Contact Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

4. Finished Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

5. Surfaces Adjacent to Field Welds . . . . . . . . . . . . . . . . . . 83 M4. Erection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

1. Alignment of Column Bases . . . . . . . . . . . . . . . . . . . . . 83

2. Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

3. Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

4. Fit of Column Compression Joints and Base Plates . . . . . . . . . 84

5. Field Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

6. Field Painting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

7. Field Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 M5. Quality Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

1. Cooperation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

2. Rejections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

3. Inspection of Welding . . . . . . . . . . . . . . . . . . . . . . . . 85

4. Inspection of Slip-Critical High-Strength Bolted Connections . . . . 85

5. Identification of Steel . . . . . . . . . . . . . . . . . . . . . . . . . 85 N. EVALUATION OF EXISTING STRUCTURES . . . . . . . . . . . . . . . 86

N1. General Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 N2. Material Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

1. Determination of Required Tests . . . . . . . . . . . . . . . . . . . 86

2. Tensile Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

3. Chemical Composition . . . . . . . . . . . . . . . . . . . . . . . . 86

4. Base Metal Notch Toughness . . . . . . . . . . . . . . . . . . . . . 87

5. Weld Metal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

6. Bolts and Rivets . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 N3. Evaluation by Structural Analysis . . . . . . . . . . . . . . . . . . . . . 87

1. Dimensional Data . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

2. Strength Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . 87

3. Serviceability Evaluation . . . . . . . . . . . . . . . . . . . . . . . 87 N4. Evaluation by Load Tests . . . . . . . . . . . . . . . . . . . . . . . . . 88

1. Determination of Live Load Rating by Testing . . . . . . . . . . . . 88

2. Serviceability Evaluation . . . . . . . . . . . . . . . . . . . . . . . 88 N5. Evaluation Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

APPENDIX B. DESIGN REQUIREMENTS . . . . . . . . . . . . . . . . . . . 89 B5. Local Buckling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

1. Classification of Steel Sections . . . . . . . . . . . . . . . . . . . . 89

3. Slender-Element Compression Sections . . . . . . . . . . . . . . . 89 APPENDIX E. COLUMNS AND OTHER COMPRESSION MEMBERS . . . 94

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SPECIFICATION (Cont’d)

E3. Design Compressive Strength for Flexural-Torsional Buckling . . . . . . 94 APPENDIX F. BEAMS AND OTHER FLEXURAL MEMBERS . . . . . . . . 96

F1. Design for Flexure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 F2. Design for Shear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

2. Design Shear Strength . . . . . . . . . . . . . . . . . . . . . . . . 102

3. Transverse Stiffeners . . . . . . . . . . . . . . . . . . . . . . . . . 102 F3. Web-Tapered Members . . . . . . . . . . . . . . . . . . . . . . . . . . 103

1. General Requirements . . . . . . . . . . . . . . . . . . . . . . . . 103

2. Design Tensile Strength . . . . . . . . . . . . . . . . . . . . . . . 103

3. Design Compressive Strength . . . . . . . . . . . . . . . . . . . . 103

4. Design Flexural Strength. . . . . . . . . . . . . . . . . . . . . . . 104

5. Design Shear Strength . . . . . . . . . . . . . . . . . . . . . . . . 106

6. Combined Flexure and Axial Force . . . . . . . . . . . . . . . . . 106 APPENDIX G. PLATE GIRDERS . . . . . . . . . . . . . . . . . . . . . . . . 107

G1. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 G2. Design Flexural Strength. . . . . . . . . . . . . . . . . . . . . . . . . 107 G3. Design Shear Strength . . . . . . . . . . . . . . . . . . . . . . . . . . 109 G4. Transverse Stiffeners . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 G5. Flexure-Shear Interaction . . . . . . . . . . . . . . . . . . . . . . . . . 111

APPENDIX H. MEMBERS UNDER COMBINED FORCES AND

TORSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 H3. Alternative Interaction Equations for Members Under Combined Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

APPENDIX J. CONNECTIONS, JOINTS, AND FASTENERS . . . . . . . . 115 J2. Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

4. Design Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 J3. Bolts and Threaded Parts . . . . . . . . . . . . . . . . . . . . . . . . . 117

7. Combined Tension and Shear in Bearing-Type Connections . . . . 117

8. High-Strength Bolts in Slip-Critical Connections . . . . . . . . . . 117

9. Combined Tension and Shear in Slip-Critical Connections . . . . . 117 APPENDIX K. CONCENTRATED FORCES, PONDING, AND FATIGUE . 118

K2. Ponding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 K3. Design for Cyclic Loading (Fatigue) . . . . . . . . . . . . . . . . . . . 121

1. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

2. Calculation of Maximum Stresses and Stress Ranges . . . . . . . . 121

3. Design Stress Range . . . . . . . . . . . . . . . . . . . . . . . . . 122

4. Bolts and Threaded Parts . . . . . . . . . . . . . . . . . . . . . . 124

5. Special Fabrication and Erection Requirements . . . . . . . . . . . 124 NUMERICAL VALUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

COMMENTARY

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

A. GENERAL PROVISIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 164 A1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 A2. Types of Construction . . . . . . . . . . . . . . . . . . . . . . . . . . 164

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A3. Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

1. Structural Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

3. Bolts, Washers, and Nuts . . . . . . . . . . . . . . . . . . . . . . 169

4. Anchor Rods and Threaded Rods . . . . . . . . . . . . . . . . . . 170

5. Filler Metal and Flux for Welding . . . . . . . . . . . . . . . . . . 170 A4. Loads and Load Combinations . . . . . . . . . . . . . . . . . . . . . . 171 A5. Design Basis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

1. Required Strength at Factored Loads . . . . . . . . . . . . . . . . 172

2. Limit States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

3. Design for Strength . . . . . . . . . . . . . . . . . . . . . . . . . 172

4. Design for Serviceability and Other Considerations . . . . . . . . 176

B. DESIGN REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . 177 B2. Net Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 B3. Effective Area of Tension Members . . . . . . . . . . . . . . . . . . . 177 B5. Local Buckling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 B7. Limiting Slenderness Ratios . . . . . . . . . . . . . . . . . . . . . . . 182

C. FRAMES AND OTHER STRUCTURES . . . . . . . . . . . . . . . . . . 184 C1. Second Order Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 C2. Frame Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 C3. Stability Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

D. TENSION MEMBERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 D1. Design Tensile Strength. . . . . . . . . . . . . . . . . . . . . . . . . . 202 D2. Built-Up Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 D3. Pin-Connected Members and Eyebars . . . . . . . . . . . . . . . . . . 202

E. COLUMNS AND OTHER COMPRESSION MEMBERS. . . . . . . . . 203 E1. Effective Length and Slenderness Limitations. . . . . . . . . . . . . . 203

1. Effective Length . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

2. Design by Plastic Analysis . . . . . . . . . . . . . . . . . . . . . 203 E2. Design Compressive Strength for Flexural Buckling. . . . . . . . . . . 203 E3. Design Compressive Strength for Flexural-Torsional Buckling . . . . . 204 E4. Built-Up Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

F. BEAMS AND OTHER FLEXURAL MEMBERS. . . . . . . . . . . . . . 206 F1. Design for Flexure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206

1. Yielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206

2. Lateral-Torsional Buckling . . . . . . . . . . . . . . . . . . . . . 206

3. Design by Plastic Analysis. . . . . . . . . . . . . . . . . . . . . . 209 F2. Design for Shear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 F4. Beams and Girders with Web Openings . . . . . . . . . . . . . . . . . 210

H. MEMBERS UNDER COMBINED FORCES AND TORSION . . . . . . 212 H1. Symmetric Members Subject to Bending and Axial Force . . . . . . . . 212 H2. Unsymmetric Members and Members Under Torsion and Combined Torsion, Flexure, Shear, and/or Axial Force . . . . . . . . . 213 H. MEMBERS UNDER COMBINED FORCES AND TORSION . . . . . . 212 H1. Symmetric Members Subject to Bending and Axial Force . . . . . . . . 212 H2. Unsymmetric Members and Members Under Torsion and Combined Torsion, Flexure, Shear, and/or Axial Force . . . . . . . . . 213

TABLE OF CONTENTS

COMMENTARY (Cont’d)

I. COMPOSITE MEMBERS . . . . . . . . . . . . . . . . . . . . . . . . . . 214 I1. Design Assumptions and Definitions . . . . . . . . . . . . . . . . . . . 214 I2. Compression Members . . . . . . . . . . . . . . . . . . . . . . . . . . 215

1. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

2. Design Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

3. Columns with Multiple Steel Shapes . . . . . . . . . . . . . . . . 216

4. Load Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 I3. Flexural Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

1. Effective Width . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

2. Design Strength of Beams with Shear Connectors . . . . . . . . . 217

3. Design Strength of Concrete-Encased Beams . . . . . . . . . . . 221

4. Strength During Construction . . . . . . . . . . . . . . . . . . . . 222

5. Formed Steel Deck . . . . . . . . . . . . . . . . . . . . . . . . . . 222

6. Design Shear Strength . . . . . . . . . . . . . . . . . . . . . . . . 225 I4. Combined Compression and Flexure . . . . . . . . . . . . . . . . . . . 225 I5. Shear Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

1. Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

2. Horizontal Shear Force . . . . . . . . . . . . . . . . . . . . . . . 226

3. Strength of Stud Shear Connectors . . . . . . . . . . . . . . . . . 227

4. Strength of Channel Shear Connectors . . . . . . . . . . . . . . . 227

6. Shear Connector Placement and Spacing . . . . . . . . . . . . . . 227 I6. Special Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

J. CONNECTIONS, JOINTS, AND FASTENERS . . . . . . . . . . . . . . 229 J1. General Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

5. Splices in Heavy Sections . . . . . . . . . . . . . . . . . . . . . . 229

8. Placement of Welds and Bolts . . . . . . . . . . . . . . . . . . . . 231

9. Bolts in Combination with Welds . . . . . . . . . . . . . . . . . . 231

10. High-Strength Bolts in Combination with Rivets . . . . . . . . . . 232 J2. Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

1. Groove Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

2. Fillet Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

4. Design Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

5. Combination of Welds . . . . . . . . . . . . . . . . . . . . . . . 239

6. Weld Metal Requirements . . . . . . . . . . . . . . . . . . . . . . 239

7. Mixed Weld Metal . . . . . . . . . . . . . . . . . . . . . . . . . . 240 J3. Bolts and Threaded Parts . . . . . . . . . . . . . . . . . . . . . . . . . 240

1. High-Strength Bolts . . . . . . . . . . . . . . . . . . . . . . . . . 240

2. Size and Use of Holes . . . . . . . . . . . . . . . . . . . . . . . . 241

3. Minimum Spacing . . . . . . . . . . . . . . . . . . . . . . . . . 241

4. Minimum Edge Distance . . . . . . . . . . . . . . . . . . . . . . 241

5. Maximum Spacing and Edge Distance . . . . . . . . . . . . . . . 242

6. Design Tension or Shear Strength . . . . . . . . . . . . . . . . . . 242

7. Combined Tension and Shear in Bearing-Type Connections . . . . 243

8. High-Strength Bolts in Slip-Critical Connections . . . . . . . . . 243

10. Bearing Strength at Bolt Holes . . . . . . . . . . . . . . . . . . . 246

11. Long Grips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 J4. Design Rupture Strength . . . . . . . . . . . . . . . . . . . . . . . . . 246 J5. Connecting Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . 248

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COMMENTARY (Cont’d)

2. Design Strength of Connecting Elements in Tension . . . . . . . . 248 J6. Fillers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 J8. Bearing Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 J9. Column Bases and Bearing on Concrete . . . . . . . . . . . . . . . . . 248

K. CONCENTRATED FORCES, PONDING, AND FATIGUE . . . . . . . . 249 K1. Flanges and Webs with Concentrated Forces . . . . . . . . . . . . . . 249

1. Design Basis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

2. Flange Local Bending . . . . . . . . . . . . . . . . . . . . . . . . 249

3. Web Local Yielding . . . . . . . . . . . . . . . . . . . . . . . . . 249

4. Web Crippling . . . . . . . . . . . . . . . . . . . . . . . . . . . 250

5. Web Sidesway Buckling . . . . . . . . . . . . . . . . . . . . . . 250

6. Web Compression Buckling . . . . . . . . . . . . . . . . . . . . 251

7. Web Panel-Zone Shear . . . . . . . . . . . . . . . . . . . . . . . 252 K2. Ponding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254

L. SERVICEABILITY DESIGN CONSIDERATIONS . . . . . . . . . . . . 257 L1. Camber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 L2. Expansion and Contraction . . . . . . . . . . . . . . . . . . . . . . . . 258 L3. Deflections, Vibration, and Drift . . . . . . . . . . . . . . . . . . . . . 258

1. Deflections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

2. Floor Vibration . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

3. Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 L5. Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

M. FABRICATION, ERECTION, AND QUALITY CONTROL . . . . . . . 260 M2. Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260

1. Cambering, Curving, and Straightening . . . . . . . . . . . . . . . 260

2. Thermal Cutting . . . . . . . . . . . . . . . . . . . . . . . . . . . 260

5. Bolted Construction . . . . . . . . . . . . . . . . . . . . . . . . . 260 M3. Shop Painting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

5. Surfaces Adjacent to Field Welds . . . . . . . . . . . . . . . . . . 261 M4. Erection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

2. Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

4. Fit of Column Compression Joints and Base Plates . . . . . . . . . 261

5. Field Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 N. EVALUATION OF EXISTING STRUCTURES. . . . . . . . . . . . . . . 262

N1. General Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 N2. Material Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262

1. Determination of Required Tests . . . . . . . . . . . . . . . . . . 262

2. Tensile Properties . . . . . . . . . . . . . . . . . . . . . . . . . . 262

4. Base Metal Notch Toughness . . . . . . . . . . . . . . . . . . . . 263

5. Weld Metal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263

6. Bolts and Rivets . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 N3. Evaluation by Structural Analysis . . . . . . . . . . . . . . . . . . . . 263

2. Strength Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . 263 N4. Evaluation by Load Tests . . . . . . . . . . . . . . . . . . . . . . . . . 263

1. Determination of Live Load Rating by Testing . . . . . . . . . . . 263

2. Serviceability Evaluation . . . . . . . . . . . . . . . . . . . . . . 264 N5. Evaluation Report. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 2. Serviceability Evaluation . . . . . . . . . . . . . . . . . . . . . . 264 N5. Evaluation Report. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

TABLE OF CONTENTS

COMMENTARY (Cont’d)

APPENDIX B. DESIGN REQUIREMENTS . . . . . . . . . . . . . . . . . . . 266 B5. Local Buckling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266

1. Classification of Steel Sections . . . . . . . . . . . . . . . . . . . 266 APPENDIX E. COLUMNS AND OTHER COMPRESSION MEMBERS. . . 267

E3. Design Compressive Strength for Flexural-Torsional Buckling . . . . . 267 APPENDIX F. BEAMS AND OTHER FLEXURAL MEMBERS . . . . . . . 268

F1. Design for Flexure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 F3. Web-Tapered Members . . . . . . . . . . . . . . . . . . . . . . . . . . 268

1. General Requirements . . . . . . . . . . . . . . . . . . . . . . . . 268

3. Design Compressive Strength . . . . . . . . . . . . . . . . . . . . 269

4. Design Flexural Strength . . . . . . . . . . . . . . . . . . . . . . 270 APPENDIX G. PLATE GIRDERS . . . . . . . . . . . . . . . . . . . . . . . . 271

G2. Design Flexural Strength . . . . . . . . . . . . . . . . . . . . . . . . . 271

APPENDIX H. MEMBERS UNDER COMBINED FORCES AND

TORSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

H3. Alternative Interaction Equations for Members Under Combined Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

APPENDIX J. CONNECTIONS, JOINTS, AND FASTENERS . . . . . . . . 273 J2. Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

4. Design Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 APPENDIX K. CONCENTRATED FORCES, PONDING, AND FATIGUE . 276

K3. Design for Cyclic Loading (Fatigue) . . . . . . . . . . . . . . . . . . . 276 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279 SUPPLEMENTARY BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . 290 K3. Design for Cyclic Loading (Fatigue) . . . . . . . . . . . . . . . . . . . 276 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279 SUPPLEMENTARY BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . 290

SYMBOLS