CẨM NANG THIẾT KẾ THÉP CẤU TRÚC

STRUCTURAL
STEEL
DESIGNER’S
HANDBOOK
Roger L. Brockenbrough

Editor

R. L. Brockenbrough & Associates, Inc.
Pittsburgh, Pennsylvania

Frederick S. Merritt

Editor

Late Consulting Engineer, West Palm Beach, Florida

Third Edition

McGRAW-HILL, INC.
New York San Francisco Washington, D.C. Auckland Bogota´
Caracas Lisbon London Madrid Mexico City Milan
Montreal New Delhi San Juan Singapore
Sydney Tokyo Toronto


Library of Congress Cataloging-in-Publication Data
Structural steel designer’s handbook / Roger L. Brockenbrough, editor,
Frederick S. Merritt, editor.—3rd ed.
p.

cm.
Includes index.
ISBN 0-07-008782-2
1. Building, Iron and steel. 2. Steel, Structural.
I. Brockenbrough, R. L. II. Merritt, Frederick S.
TA684.S79 1994
624.1Ј821—dc20
93-38088
CIP

Copyright ᭧ 1999, 1994, 1972 by McGraw-Hill, Inc. All rights reserved.
Printed in the United States of America. Except as permitted under the United
States Copyright Act of 1976, no part of this publication may be reproduced
or distributed in any form or by any means, or stored in a data base or
retrieval system, without the prior written permission of the publisher.
1 2 3 4 5 6 7 8 9 0

DOC / DOC

9 9 8 7 6 5 4 3

ISBN 0-07-008782-2

The sponsoring editor for this book was Larry S. Hager, the editing
supervisor was Steven Melvin, and the production supervisor was Sherri
Souffrance. It was set in Times Roman by Pro-Image Corporation.
Printed and bound by R. R. Donnelley & Sons Company.
This book is printed on acid-free paper.

Information contained in this work has been obtained by McGraw-Hill, Inc. from sources believed to be reliable. However,

neither McGraw-Hill nor its authors guarantees the accuracy or
completeness of any information published herein and neither McGraw-Hill nor its authors shall be responsible for any errors,
omissions, or damages arising out of use of this information. This
work is published with the understanding that McGraw-Hill and
its authors are supplying information but are not attempting to
render engineering or other professional services. If such services
are required, the assistance of an appropriate professional should
be sought.


Other McGraw-Hill Book Edited by Roger L. Brockenbrough
Brockenbrough & Boedecker •

HIGHWAY ENGINEERING HANDBOOK

Other McGraw-Hill Books Edited by Frederick S. Merritt
Merritt • STANDARD HANDBOOK FOR CIVIL ENGINEERS
Merritt & Ricketts • BUILDING DESIGN AND CONSTRUCTION

HANDBOOK

Other McGraw-Hill Books of Interest
Beall • MASONRY DESIGN AND DETAILING
Breyer • DESIGN OF WOOD STRUCTURES
Brown • FOUNDATION BEHAVIOR AND REPAIR
Faherty & Williamson • WOOD ENGINEERING AND CONSTRUCTION HANDBOOK
Gaylord & Gaylord • STRUCTURAL ENGINEERING HANDBOOK
Harris • NOISE CONTROL IN BUILDINGS
Kubal • WATERPROOFING THE BUILDING ENVELOPE
Newman • STANDARD HANDBOOK OF STRUCTURAL DETAILS FOR BUILDING CONSTRUCTION

Sharp • BEHAVIOR AND DESIGN OF ALUMINUM STRUCTURES
Waddell & Dobrowolski • CONCRETE CONSTRUCTION HANDBOOK


CONTRIBUTORS

Boring, Delbert F., P.E. Senior Director, Construction Market, American Iron and Steel
Institute, Washington, D.C. (SECTION 6 BUILDING DESIGN CRITERIA)
Brockenbrough, Roger L., P.E. R. L. Brockenbrough & Associates, Inc., Pittsburgh, Penn-

sylvania (SECTION 1 PROPERTIES OF STRUCTURAL STEELS AND EFFECTS OF STEELMAKING AND
FABRICATION; SECTION 10 COLD-FORMED STEEL DESIGN)
Cuoco, Daniel A., P.E. Principal, LZA Technology/Thornton-Tomasetti Engineers, New York,
New York (SECTION 8 FLOOR AND ROOF SYSTEMS)
Cundiff, Harry B., P.E. HBC Consulting Service Corp., Atlanta, Georgia (SECTION 11 DESIGN
CRITERIA FOR BRIDGES)

Geschwindner, Louis F., P.E. Professor of Architectural Engineering, Pennsylvania State

University, University Park, Pennsylvania (SECTION 4 ANALYSIS OF SPECIAL STRUCTURES)
Haris, Ali A. K., P.E. President, Haris Enggineering, Inc., Overland Park, Kansas (SECTION
7 DESIGN OF BUILDING MEMBERS)

Hedgren, Arthur W. Jr., P.E. Senior Vice President, HDR Engineering, Inc., Pittsburgh,
Pennsylvania (SECTION 14 ARCH BRIDGES)
Hedefine, Alfred, P.E. Former President, Parsons, Brinckerhoff, Quade & Douglas, Inc.,

New York, New York (SECTION 12 BEAM AND GIRDER BRIDGES)
Kane, T., P.E. Cives Steel Company, Roswell, Georgia (SECTION 5 CONNECTIONS)
Kulicki, John M., P.E. President and Chief Engineer, Modjeski and Masters, Inc., Harris-

burg, Pennsylvania (SECTION 13 TRUSS BRIDGES)
LaBoube, R. A., P.E. Associate Professor of Civil Engineering, University of Missouri-Rolla,

Rolla, Missouri (SECTION 6 BUILDING DESIGN CRITERIA)
LeRoy, David H., P.E. Vice President, Modjeski and Masters, Inc., Harrisburg, Pennsylvania

(SECTION 13 TRUSS BRIDGES)
Mertz, Dennis, P.E. Associate Professor of Civil Engineering, University of Delaware, New-

ark, Delaware (SECTION 11 DESIGN CRITERIA FOR BRIDGES)
Nickerson, Robert L., P.E. Consultant-NBE, Ltd., Hempstead, Maryland (SECTION 11 DESIGN
CRITERIA FOR BRIDGES)

Podolny, Walter, Jr., P.E. Senior Structural Engineer Bridge Division, Office of Bridge
Technology, Federal Highway Administration, U.S. Department of Transportation, Washington, D. C. (SECTION 15 CABLE-SUSPENDED BRIDGES)
Prickett, Joseph E., P.E. Senior Associate, Modjeski and Masters, Inc., Harrisburg, Penn-

sylvania (SECTION 13 TRUSS BRIDGES)
xv


xvi

CONTRIBUTORS

Roeder, Charles W., P.E. Professor of Civil Engineering, University of Washington, Seattle,

Washington (SECTION 9 LATERAL-FORCE DESIGN)
Schflaly, Thomas, Director, Fabricating & Standards, American Institute of Steel Construc-

tion, Inc., Chicago, Illinois (SECTION 2 FABRICATION AND ERECTION)
Sen, Mahir, P.E. Professional Associate, Parsons Brinckerhoff, Inc., Princeton, New Jersey
(SECTION 12 BEAM AND GIRDER BRIDGES)
Swindlehurst, John, P.E. Former Senior Professional Associate, Parsons Brinckerhoff, Inc.,
West Trenton, New Jersey (SECTION 12 BEAM AND GIRDER BRIDGES)
Thornton, William A., P.E. Chief Engineer, Cives Steel Company, Roswell, Georgia (SECTION 5 CONNECTIONS)

Ziemian, Ronald D., Associate Professor of Civil Engineering, Bucknell University, Lew-

isburg, Pennsylvania (SECTION 3 GENERAL STRUCTURAL THEORY)


FACTORS FOR
CONVERSION TO
SI UNITS OF
MEASUREMENT

TO CONVERT FROM
CUSTOMARY U.S. UNIT

TO
METRIC UNIT

MULTIPLY BY

inch
foot

mm

mm

25.4
304.8

Mass

lb

kg

0.45359

Mass/unit length

plf

kg/m

1.488 16

Mass/unit area

psf

kg/m2

4.882 43

Mass density

pcf

kg/m3

16.018 5

pound
kip
kip

N
N
kN

4.448 22
4448.22
4.448 22

Force/unit length

klf
klf

N/mm
kN/m

14.593 9
14.593 9

Stress

ksi
psi

MPa
kPa

6.894 76
6.894 76

Bending Moment

foot-kips
foot-kips

N-mm
kN-m

1 355 817
1.355 817

Moment of inertia

in4

mm4

416 231

Section modulus

in3

mm3

16 387.064

QUANTITY
Length

Force

xxi


PREFACE TO THE THIRD EDITION

This edition of the handbook has been updated throughout to reflect continuing changes in
design trends and improvements in design specifications. Criteria and examples are included
for both allowable-stress design (ASD) and load-and-resistance-factor design (LRFD) methods, but an increased emphasis has been placed on LRFD to reflect its growing use in
practice.
Numerous connection designs for building construction are presented in LRFD format in
conformance with specifications of the American Institute of Steel Construction (AISC). A
new article has been added on the design of hollow structural sections (HSS) by LRFD,
based on a new separate HSS specification by AISC. Also, because of their growing use in
light commercial and residential applications, a new section has been added on the design
of cold-formed steel structural members, based on the specification by the American Iron
and Steel Institute (AISI). It is applicable to both ASD and LRFD.
Design criteria are now presented in separate parts for highway and railway bridges to

better concentrate on those subjects. Information on highway bridges is based on specifications of the American Association of State Highway and Transportation Officials (AASHTO)
and information on railway bridges is based on specifications of the American Railway
Engineering and Maintenance-of-Way Association (AREMA). A very detailed example of
the LRFD design of a two-span composite I-girder highway bridge has been presented in
Section 11 to illustrate AASHTO criteria, and also the LRFD design of a single-span composite bridge in Section 12. An example of the LRFD design of a truss member is presented
in Section 13.
This edition of the handbook regrettably marks the passing of Fred Merritt, who worked
tirelessly on previous editions, and developed many other handbooks as well. His many
contributions to these works are gratefully acknowledged.
Finally, the reader is cautioned that independent professional judgment must be exercised
when information set forth in this handbook is applied. Anyone making use of this information assumes all liability arising from such use. Users are encouraged to use the latest
edition of the referenced specifications, because they provide more complete information and
are subject to frequent change.
Roger L. Brockenbrough

xvii


PREFACE TO THE SECOND
EDITION

This handbook has been developed to serve as a comprehensive reference source for designers of steel structures. Included is information on materials, fabrication, erection, structural theory, and connections, as well as the many facets of designing structural-steel systems
and members for buildings and bridges. The information presented applies to a wide range
of structures.
The handbook should be useful to consulting engineers; architects; construction contractors; fabricators and erectors; engineers employed by federal, state, and local governments;
and educators. It will also be a good reference for engineering technicians and detailers. The
material has been presented in easy-to-understand form to make it useful to professionals
and those with more limited experience. Numerous examples, worked out in detail, illustrate
design procedures.
The thrust is to provide practical techniques for cost-effective design as well as explanations of underlying theory and criteria. Design methods and equations from leading specifications are presented for ready reference. This includes those of the American Institute of

Steel Construction (AISC), the American Association of State Highway and Transportation
Officials (AASHTO), and the American Railway Engineering Association (AREA). Both the
traditional allowable-stress design (ASD) approach and the load-and-resistance-factor design
(LRFD) approach are presented. Nevertheless, users of this handbook would find it helpful
to have the latest edition of these specifications on hand, because they are changed annually,
as well as the AISC ‘‘Steel Construction Manual,’’ ASD and LRFD.
Contributors to this book are leading experts in design, construction, materials, and structural theory. They offer know-how and techniques gleaned from vast experience. They include well-known consulting engineers, university professors, and engineers with an extensive fabrication and erection background. This blend of experiences contributes to a broad,
well-rounded presentation.
The book begins with an informative section on the types of steel, their mechanical
properties, and the basic behavior of steel under different conditions. Topics such as coldwork, strain-rate effects, temperature effects, fracture, and fatigue provide in-depth information. Aids are presented for estimating the relative weight and material cost of steels for
various types of structural members to assist in selecting the most economical grade. A
review of fundamental steel-making practices, including the now widely used continuouscasting method, is presented to give designers better knowledge of structural steels and alloys
and how they are produced.
Because of their impact on total cost, a knowledge of fabrication and erection methods
is a fundamental requirement for designing economical structures. Accordingly, the book
presents description of various shop fabrication procedures, including cutting steel components to size, punching, drilling, and welding. Available erection equipment is reviewed, as
well as specific methods used to erect bridges and buildings.
A broad treatment of structural theory follows to aid engineers in determining the forces
and moments that must be accounted for in design. Basic mechanics, traditional tools for
xix


xx

PREFACE

analysis of determinate and indeterminate structures, matrix methods, and other topics are
discussed. Structural analysis tools are also presented for various special structures, such as
arches, domes, cable systems, and orthotropic plates. This information is particularly useful
in making preliminary designs and verifying computer models.

Connections have received renewed attention in current structural steel design, and improvements have been made in understanding their behavior in service and in design techniques. A comprehensive section on design of structural connections presents approved methods for all of the major types, bolted and welded. Information on materials for bolting and
welding is included.
Successive sections cover design of buildings, beginning with basic design criteria and
other code requirements, including minimum design dead, live, wind, seismic, and other
loads. A state-of-the-art summary describes current fire-resistant construction, as well as
available tools that allow engineers to design for fire protection and avoid costly tests. In
addition, the book discusses the resistance of various types of structural steel to corrosion
and describes corrosion-prevention methods.
A large part of the book is devoted to presentation of practical approaches to design of
tension, compression, and flexural members, composite and noncomposite.
One section is devoted to selection of floor and roof systems for buildings. This involves
decisions that have major impact on the economics of building construction. Alternative
support systems for floors are reviewed, such as the stub-girder and staggered-truss systems.
Also, framing systems for short and long-span roof systems are analyzed.
Another section is devoted to design of framing systems for lateral forces. Both traditional
and newer-type bracing systems, such as eccentric bracing, are analyzed.
Over one-third of the handbook is dedicated to design of bridges. Discussions of design
criteria cover loadings, fatigue, and the various facets of member design. Information is
presented on use of weathering steel. Also, tips are offered on how to obtain economical
designs for all types of bridges. In addition, numerous detailed calculations are presented
for design of rolled-beam and plate-girder bridges, straight and curved, composite and noncomposite, box girders, orthotropic plates, and continuous and simple-span systems.
Notable examples of truss and arch designs, taken from current practice, make these
sections valuable references in selecting the appropriate spatial form for each site, as well
as executing the design.
The concluding section describes the various types of cable-supported bridges and the
cable systems and fittings available. In addition, design of suspension bridges and cablestayed bridges is covered in detail.
The authors and editors are indebted to numerous sources for the information presented.
Space considerations preclude listing all, but credit is given wherever feasible, especially in
bibliographies throughout the book.
The reader is cautioned that independent professional judgment must be exercised when

information set forth in this handbook is applied. Anyone making use of this information
assumes all liability arising from such use.
Roger L. Brockenbrough
Frederick S. Merritt


CONTENTS

Contributors
xv
Preface
xvii

Section 1. Properties of Structural Steels and Effects of Steelmaking and
Fabrication Roger L. Brockenbrough, P.E.
1.1.
1.2.
1.3.
1.4.
1.5.
1.6.
1.7.
1.8.
1.9.
1.10.
1.11.
1.12.
1.13.
1.14.
1.15.

1.16.
1.17.
1.18.
1.19.
1.20.
1.21.
1.22.
1.23.
1.24.
1.25.
1.26.
1.27.
1.28.

Structural Steel Shapes and Plates / 1.1
Steel-Quality Designations / 1.6
Relative Cost of Structural Steels / 1.8
Steel Sheet and Strip for Structural Applications / 1.10
Tubing for Structural Applications / 1.13
Steel Cable for Structural Applications / 1.13
Tensile Properties / 1.14
Properties in Shear / 1.16
Hardness Tests / 1.17
Effect of Cold Work on Tensile Properties / 1.18
Effect of Strain Rate on Tensile Properties / 1.19
Effect of Elevated Temperatures on Tensile Properties / 1.20
Fatigue / 1.22
Brittle Fracture / 1.23
Residual Stresses / 1.26
Lamellar Tearing / 1.28

Welded Splices in Heavy Sections / 1.28
k-Area Cracking / 1.29
Variations in Mechanical Properties / 1.29
Changes in Carbon Steels on Heating and Cooling / 1.30
Effects of Grain Size / 1.32
Annealing and Normalizing / 1.32
Effects of Chemistry on Steel Properties / 1.33
Steelmaking Methods / 1.35
Casting and Hot Rolling / 1.36
Effects of Punching Holes and Shearing / 1.39
Effects of Welding / 1.39
Effects of Thermal Cutting / 1.40

Section 2. Fabrication and Erection Thomas Schflaly
2.1.
2.2.
2.3.
2.4.

1.1

2.1

Shop Detail Drawings / 2.1
Cutting, Shearing, and Sawing / 2.3
Punching and Drilling / 2.4
CNC Machines / 2.4

v

vi

CONTENTS

2.5.
2.6.
2.7.
2.8.
2.9.
2.10.
2.11.
2.12.
2.13.
2.14.
2.15.
2.16.
2.17.

Bolting / 2.5
Welding / 2.5
Camber / 2.8
Shop Preassembly / 2.9
Rolled Sections / 2.11
Built-Up Sections / 2.12
Cleaning and Painting / 2.15
Fabrication Tolerances / 2.16
Erection Equipment / 2.17
Erection Methods for Buildings / 2.20
Erection Procedure for Bridges / 2.23

Field Tolerances / 2.25
Safety Concerns / 2.27

Section 3. General Structural Theory Ronald D. Ziemian, Ph.D.
3.1. Fundamentals of Structural Theory / 3.1
STRUCTURAL MECHANICS—STATICS
3.2.
3.3.
3.4.
3.5.

Principles of Forces / 3.2
Moments of Forces / 3.5
Equations of Equilibrium / 3.6
Frictional Forces / 3.8
STRUCTURAL MECHANICS—DYNAMICS

3.6. Kinematics / 3.10
3.7. Kinetics / 3.11
MECHANICS

OF

MATERIALS

3.8.
3.9.
3.10.
3.11.
3.12.

Stress-Strain Diagrams / 3.13
Components of Stress and Strain / 3.14
Stress-Strain Relationships / 3.17
Principal Stresses and Maximum Shear Stress / 3.18
Mohr’s Circle / 3.20

3.13.
3.14.
3.15.
3.16.
3.17.
3.18.
3.19.
3.20.
3.21.

Types of Structural Members and Supports / 3.21
Axial-Force Members / 3.22
Members Subjected to Torsion / 3.24
Bending Stresses and Strains in Beams / 3.25
Shear Stresses in Beams / 3.29
Shear, Moment, and Deformation Relationships in Beams / 3.34
Shear Deflections in Beams / 3.45
Members Subjected to Combined Forces / 3.46
Unsymmetrical Bending / 3.48

BASIC BEHAVIOR

CONCEPTS

3.22.
3.23.
3.24.
3.25.

OF

STRUCTURAL COMPONENTS

WORK

AND

ENERGY

Work of External Forces / 3.50
Virtual Work and Strain Energy / 3.51
Castigliano’s Theorems / 3.56
Reciprocal Theorems / 3.57
ANALYSIS

3.26.
3.27.
3.28.
3.29.

OF

OF

STRUCTURAL SYSTEMS

Types of Loads / 3.59
Commonly Used Structural Systems / 3.60
Determinancy and Geometric Stability / 3.62
Calculation of Reactions in Statically Determinate Systems / 3.63

3.1


CONTENTS

3.30.
3.31.
3.32.
3.33.
3.34.
3.35.
3.36.
3.37.
3.38.
3.39.
3.40.

Forces in Statically Determinate Trusses / 3.64
Deflections of Statically Determinate Trusses / 3.66
Forces in Statically Determinate Beams and Frames / 3.68
Deformations in Beams / 3.69
Methods for Analysis of Statically Indeterminate Systems / 3.73
Force Method (Method of Consistent Deflections) / 3.74

Displacement Methods / 3.76
Slope-Deflection Method / 3.78
Moment-Distribution Method / 3.81
Matrix Stiffness Method / 3.84
Influence Lines / 3.89
INSTABILITY

3.41.
3.42.
3.43.
3.44.

OF

STRUCTURAL COMPONENTS

Elastic Flexural Buckling of Columns / 3.93
Elastic Lateral Buckling of Beams / 3.96
Elastic Flexural Buckling of Frames / 3.98
Local Buckling / 3.99
NONLINEAR BEHAVIOR

3.45.
3.46.
3.47.
3.48.
3.49.
3.50.
3.51.

vii

OF

STRUCTURAL SYSTEMS

Comparisons of Elastic and Inelastic Analyses / 3.99
General Second-Order Effects / 3.101
Approximate Amplification Factors for Second-Order Effects / 3.103
Geometric Stiffness Matrix Method for Second-Order Effects / 3.105
General Material Nonlinear Effects / 3.105
Classical Methods of Plastic Analysis / 3.109
Contemporary Methods of Inelastic Analysis / 3.114
TRANSIENT LOADING

3.52.
3.53.
3.54.
3.55.

General Concepts of Structural Dynamics / 3.114
Vibration of Single-Degree-of-Freedom Systems / 3.116
Material Effects of Dynamic Loads / 3.118
Repeated Loads / 3.118

Section 4. Analysis of Special Structures Louis F. Geschwindner, P.E.
4.1.
4.2.
4.3.
4.4.

4.5.
4.6.
4.7.
4.8.
4.9.
4.10.
4.11.
4.12.
4.13.

4.1

Three-Hinged Arches / 4.1
Two-Hinged Arches / 4.3
Fixed Arches / 4.5
Stresses in Arch Ribs / 4.7
Plate Domes / 4.8
Ribbed Domes / 4.11
Ribbed and Hooped Domes / 4.19
Schwedler Domes / 4.22
Simple Suspension Cables / 4.23
Cable Suspension Systems / 4.29
Plane-Grid Frameworks / 4.34
Folded Plates / 4.42
Orthotropic Plates / 4.48

Section 5. Connections William A. Thornton, P.E., and T. Kane, P.E.
5.1. Limitations on Use of Fasteners and Welds / 5.1
5.2. Bolts in Combination with Welds / 5.2
FASTENERS

5.3. High-Strength Bolts, Nuts, and Washers / 5.2

5.1


viii

CONTENTS

5.4. Carbon-Steel or Unfinished (Machine) Bolts / 5.5
5.5. Welded Studs / 5.5
5.6. Pins / 5.7
GENERAL CRITERIA
5.7.
5.8.
5.9.
5.10.
5.11.
5.12.
5.13.
5.14.

BOLTED CONNECTIONS

FOR

Fastener Diameters / 5.10
Fastener Holes / 5.11
Minimum Number of Fasteners / 5.12
Clearances for Fasteners / 5.13

Fastener Spacing / 5.13
Edge Distance of Fasteners / 5.14
Fillers / 5.16
Installation of Fasteners / 5.17
WELDS

5.15.
5.16.
5.17.
5.18.

Welding Materials / 5.20
Types of Welds / 5.21
Standard Welding Symbols / 5.25
Welding Positions / 5.30
GENERAL CRITERIA

5.19.
5.20.
5.21.
5.22.
5.23.

WELDED CONNECTIONS

Limitations on Fillet-Weld Dimensions / 5.31
Limitations on Plug and Slot Weld Dimensions / 5.33
Welding Procedures / 5.33
Weld Quality / 5.36
Welding Clearance and Space / 5.38

DESIGN

5.24.
5.25.
5.26.
5.27.
5.28.
5.29.
5.30.
5.31.
5.32.
5.33.
5.34.
5.35.
5.36.
5.37.

FOR

OF

CONNECTIONS

Minimum Connections / 5.39
Hanger Connections / 5.39
Tension Splices / 5.47
Compression Splices / 5.50
Column Base Plates / 5.54
Beam Bearing Plates / 5.60
Shear Splices / 5.62

Bracket Connections / 5.67
Connections for Simple Beams / 5.77
Moment Connections / 5.86
Beams Seated Atop Supports / 5.95
Truss Connections / 5.96
Connections for Bracing / 5.98
Crane-Girder Connections / 5.107

Section 6. Building Design Criteria R. A. LaBoube, P.E.
6.1.
6.2.
6.3.
6.4.
6.5.
6.6.
6.7.
6.8.
6.9.
6.10.
6.11.

Building Codes / 6.1
Approval of Special Construction / 6.2
Standard Specifications / 6.2
Building Occupancy Loads / 6.2
Roof Loads / 6.9
Wind Loads / 6.10
Seismic Loads / 6.21
Impact Loads / 6.26
Crane-Runway Loads / 6.26

Restraint Loads / 6.28
Combined Loads / 6.28

6.1


CONTENTS

6.12.
6.13.
6.14.
6.15.
6.16.
6.17.
6.18.
6.19.
6.20.
6.21.
6.22.
6.23.
6.24.
6.25.
6.26.
6.27.
6.28.
6.29.
6.30.
6.31.
6.32.
6.33.

ASD and LRFD Specifications / 6.29
Axial Tension / 6.30
Shear / 6.34
Combined Tension and Shear / 6.40
Compression / 6.41
Bending Strength / 6.45
Bearing / 6.48
Combined Bending and Compression / 6.48
Combined Bending and Tension / 6.50
Wind and Seismic Stresses / 6.51
Fatigue Loading / 6.51
Local Plate Buckling / 6.62
Design Parameters for Tension Members / 6.64
Design Parameters for Rolled Beams and Plate Girders / 6.64
Criteria for Composite Construction / 6.67
Serviceability / 6.74
Built-Up Compression Members / 6.76
Built-Up Tension Members / 6.77
Plastic Design / 6.78
Hollow Structural Sections / 6.79
Cable Construction / 6.85
Fire Protection / 6.85

Section 7. Design of Building Members Ali A. K. Haris, P.E.
7.1.
7.2.
7.3.
7.4.
7.5.

7.6.
7.7.
7.8.
7.9.
7.10.
7.11.
7.12.
7.13.
7.14.
7.15.
7.16.
7.17.
7.18.

ix

7.1

Tension Members / 7.1
Comparative Designs of Double-Angle Hanger / 7.3
Example—LRFD for Wide-Flange Truss Members / 7.4
Compression Members / 7.5
Example—LRFD for Steel Pipe in Axial Compression / 7.6
Comparative Designs of Wide-Flange Section with Axial Compression / 7.7
Example—LRFD for Double Angles with Axial Compression / 7.8
Steel Beams / 7.10
Comparative Designs of Single-Span Floorbeam / 7.11
Example—LRFD for Floorbeam with Unbraced Top Flange / 7.14
Example—LRFD for Floorbeam with Overhang / 7.16
Composite Beams / 7.18

LRFD for Composite Beam with Uniform Loads / 7.20
Example—LRFD for Composite Beam with Concentrated Loads and End
Moments / 7.28
Combined Axial Load and Biaxial Bending / 7.32
Example—LRFD for Wide-Flange Column in a Multistory Rigid Frame / 7.33
Base Plate Design / 7.37
Example—LRFD of Column Base Plate / 7.39

Section 8. Floor and Roof Systems Daniel A. Cuoco, P.E.
FLOOR DECKS
8.1. Concrete Fill on Metal Deck / 8.1
8.2. Precast-Concrete Plank / 8.8
8.3. Cast-in-Place Concrete Slabs / 8.9
ROOF DECKS
8.4. Metal Roof Deck / 8.10
8.5. Lightweight Precast-Concrete Roof Panels / 8.11

8.1


x

CONTENTS

8.6. Wood-Fiber Planks / 8.11
8.7. Gypsum-Concrete Decks / 8.13
FLOOR FRAMING
8.8.
8.9.
8.10.

8.11.
8.12.
8.13.
8.14.
8.15.
8.16.
8.17.
8.18.

Rolled Shapes / 8.14
Open-Web Joists / 8.17
Lightweight Steel Framing / 8.18
Trusses / 8.18
Stub-Girders / 8.19
Staggered Trusses / 8.21
Castellated Beams / 8.21
ASD versus LRFD / 8.25
Dead-Load Deflection / 8.25
Fire Protection / 8.25
Vibrations / 8.28
ROOF FRAMING

8.19.
8.20.
8.21.
8.22.
8.23.

Plate Girders / 8.29
Space Frames / 8.29

Arched Roofs / 8.30
Dome Roofs / 8.31
Cable Structures / 8.33

Section 9. Lateral-Force Design Charles W. Roeder, P.E.
9.1.
9.2.
9.3.
9.4.
9.5.
9.6.
9.7.
9.8.
9.9.

9.1

Description of Wind Forces / 9.1
Determination of Wind Loads / 9.4
Seismic Loads in Model Codes / 9.9
Equivalent Static Forces for Seismic Design / 9.10
Dynamic Method of Seismic Load Distribution / 9.14
Structural Steel Systems for Seismic Design / 9.17
Seismic-Design Limitations on Steel Frames / 9.22
Forces in Frames Subjected to Lateral Loads / 9.33
Member and Connection Design for Lateral Loads / 9.38

Section 10. Cold-Formed Steel Design R. L. Brockenbrough, P.E.
10.1.
10.2.

10.3.
10.4.
10.5.
10.6.
10.7.
10.8.
10.9.
10.10.
10.11.
10.12.
10.13.
10.14.
10.15.
10.16.
10.17.
10.18.

10.1

Design Specifications and Materials / 10.1
Manufacturing Methods and Effects / 10.2
Nominal Loads / 10.4
Design Methods / 10.5
Section Property Calculations / 10.7
Effective Width Concept / 10.7
Maximum Width-to-Thickness Ratios / 10.11
Effective Widths of Stiffened Elements / 10.11
Effective Widths of Unstiffened Elements / 10.14
Effective Widths of Uniformly Compressed Elements with Edge Stiffener / 10.14
Tension Members / 10.16

Flexural Members / 10.16
Concentrically Loaded Compression Members / 10.25
Combined Tensile Axial Load and Bending / 10.27
Combined Compressive Axial Load and Bending / 10.27
Cylindrical Tubular Members / 10.30
Welded Connections / 10.30
Bolted Connections / 10.34


CONTENTS

10.19.
10.20.
10.21.
10.22.
10.23.

xi

Screw Connections / 10.37
Other Limit States at Connections / 10.41
Wall Stud Assemblies / 10.41
Example of Effective Section Calculation / 10.42
Example of Bending Strength Calculation / 10.45

Section 11. Design Criteria for Bridges

Part 1. Application of Criteria for Cost-Effective Highway Bridge
Design Robert L. Nickerson, P.E., and Dennis Mertz, P.E.

11.1

11.1

11.1. Standard Specifications / 11.1
11.2. Design Methods / 11.2
11.3. Primary Design Considerations / 11.2
11.4. Highway Design Loadings / 11.4
11.5. Load Combinations and Effects / 11.13
11.6. Nominal Resistance for LRFD / 11.19
11.7. Distribution of Loads through Decks / 11.20
11.8. Basic Allowable Stresses for Bridges / 11.24
11.9. Fracture Control / 11.29
11.10. Repetitive Loadings / 11.30
11.11. Detailing for Earthquakes / 11.35
11.12. Detailing for Buckling / 11.36
11.13. Criteria for Built-Up Tension Members / 11.45
11.14. Criteria for Built-Up Compression Members / 11.46
11.15. Plate Girders and Cover-Plated Rolled Beams / 11.48
11.16. Composite Construction with I Girders / 11.50
11.17. Cost-Effective Plate-Girder Designs / 11.54
11.18. Box Girders / 11.56
11.19. Hybrid Girders / 11.60
11.20. Orthotropic-Deck Bridges / 11.61
11.21. Span Lengths and Deflections / 11.63
11.22. Bearings / 11.63
11.23. Detailing for Weldability / 11.67
11.24. Stringer or Girder Spacing / 11.69
11.25. Bridge Decks / 11.69
11.26. Elimination of Expansion Joints in Highway Bridges / 11.72

11.27. Bridge Steels and Corrosion Protection / 11.74
11.28. Constructability / 11.77
11.29. Inspectability / 11.77
11.30. Reference Materials / 11.78
Appendix A. Example of LRFD Design for Two-Span Continuous
Composite I Girder / 11.78

Part 2. Railroad Bridge Design Harry B. Cundiff, P.E.
11.31.
11.32.
11.33.
11.34.
11.35.
11.36.
11.37.
11.38.
11.39.
11.40.

Standard Specifications / 11.153
Design Method / 11.153
Owner’s Concerns / 11.153
Design Considerations / 11.154
Design Loadings / 11.155
Composite Steel and Concrete Spans / 11.163
Basic Allowable Stresses / 11.164
Fatigue Design / 11.168
Fracture Critical Members / 11.170
Impact Test Requirements for Structural Steel / 11.171

11.80


xii

CONTENTS

11.41.
11.42.
11.43.
11.44.
11.45.

General Design Provisions / 11.171
Compression Members / 11.173
Stay Plates / 11.174
Members Stressed Primarily in Bending / 11.174
Other Considerations / 11.178

Section 12. Beam and Girder Bridges Alfred Hedefine, P.E.,
John Swindlehurst, P.E., and Mahir Sen, P.E.

12.1

12.1. Characteristics of Beam Bridges / 12.1
12.2. Example—Allowable-Stress Design of Composite, Rolled-Beam Stringer Bridge /
12.5
12.3. Characteristics of Plate-Girder Stringer Bridges / 12.20
12.4. Example—Allowable-Stress Design of Composite, Plate-Girder Bridge / 12.23
12.5. Example—Load-Factor Design of Composite Plate-Girder Bridge / 12.34

12.6. Characteristics of Curved Girder Bridges / 12.48
12.7. Example—Allowable-Stress Design of Curved Stringer Bridge / 12.56
12.8. Deck Plate-Girder Bridges with Floorbeams / 12.69
12.9. Example—Allowable-Stress Design of Deck Plate-Girder Bridge with
Floorbeams / 12.70
12.10. Through Plate-Girder Bridges with Floorbeams / 12.104
12.11. Example—Allowable-Stress Design of a Through Plate-Girder Bridge / 12.105
12.12. Composite Box-Girder Bridges / 12.114
12.13. Example—Allowable-Stress Design of a Composite Box-Girder Bridge / 12.118
12.14. Orthotropic-Plate Girder Bridges 1 12.128
12.15. Example—Design of an Orthotropic-Plate Box-Girder Bridge / 12.130
12.16. Continuous-Beam Bridges / 12.153
12.17. Allowable-Stress Design of Bridge with Continuous, Composite Stringers /
12.154
12.18. Example—Load and Resistance Factor Design (LRFD) of Composite Plate-Girder
Bridge / 12.169

Section 13. Truss Bridges John M. Kulicki, P.E., Joseph E. Prickett, P.E.,
and David H. LeRoy, P.E.
13.1.
13.2.
13.3.
13.4.
13.5.
13.6.
13.7.
13.8.
13.9.
13.10.
13.11.

13.12.
13.13.
13.14.
13.15.
13.16.
13.17.
13.18.

Specifications / 13.2
Truss Components / 13.2
Types of Trusses / 13.5
Bridge Layout / 13.6
Deck Design / 13.8
Lateral Bracing, Portals, and Sway Frames / 13.9
Resistance to Longitudinal Forces / 13.10
Truss Design Procedure / 13.10
Truss Member Details / 13.18
Member and Joint Design Examples—LFD and SLD / 13.21
Member Design Example—LRFD / 13.27
Truss Joint Design Procedure / 13.35
Example—Load-Factor Design of Truss Joint / 13.37
Example—Service-Load Design of Truss Joint / 13.44
Skewed Bridges / 13.49
Truss Bridges on Curves / 13.50
Truss Supports and Other Details / 13.51
Continuous Trusses / 13.51

13.1

CONTENTS

Section 14. Arch Bridges Arthur W Hedgren, Jr., P.E.
14.1.
14.2.
14.3.
14.4.
14.5.
14.6.
14.7.
14.8.
14.9.
14.10.
14.11.

14.1

Types of Arches / 14.2
Arch Forms / 14.2
Selection of Arch Type and Form / 14.3
Comparison of Arch with Other Bridge Types / 14.5
Erection of Arch Bridges / 14.6
Design of Arch Ribs and Ties / 14.7
Design of Other Elements / 14.10
Examples of Arch Bridges / 14.11
Guidelines for Preliminary Designs and Estimates / 14.44
Buckling Considerations for Arches / 14.46
Example—Design of Tied-Arch Bridge / 14.47

Section 15. Cable-Suspended Bridges Walter Podolny, Jr., P.E.

15.1.
15.2.
15.3.
15.4.
15.5.
15.6.
15.7.
15.8.
15.9.
15.10.
15.11.
15.12.
15.13.
15.14.
15.15.
15.16.
15.17.
15.18.
15.19.
15.20.
15.21.
15.22.
15.23.

xiii

Evolution of Cable-Suspended Bridges / 15.1
Classification of Cable-Suspended Bridges / 15.5
Classification and Characteristics of Suspension Bridges / 15.7
Classification and Characteristics of Cable-Stayed Bridges / 15.16

Classification of Bridges by Span / 15.23
Need for Longer Spans / 15.24
Population Demographics of Suspension Bridges / 15.29
Span Growth of Suspension Bridges / 15.30
Technological Limitations to Future Development / 15.30
Cable-Suspended Bridges for Rail Loading / 15.31
Specifications and Loadings for Cable-Suspended Bridges / 15.32
Cables / 15.35
Cable Saddles, Anchorages, and Connections / 15.41
Corrosion Protection of Cables / 15.45
Statics of Cables / 15.52
Suspension-Bridge Analysis / 15.53
Preliminary Suspension-Bridge Design / 15.68
Self-Anchored Suspension Bridges / 15.74
Cable-Stayed Bridge Analysis / 15.75
Preliminary Design of Cable-Stayed Bridges / 15.79
Aerodynamic Analysis of Cable-Suspended Bridges / 15.86
Seismic Analysis of Cable-Suspended Structures / 15.96
Erection of Cable-Suspended Bridges / 15.97

Index I.1 (Follows Section 15.)

15.1


SECTION 1

PROPERTIES OF STRUCTURAL
STEELS AND EFFECTS OF
STEELMAKING AND FABRICATION

R. L. Brockenbrough, P.E.
President, R. L. Brockenbrough & Associates, Inc.,
Pittsburgh, Pennsylvania

This section presents and discusses the properties of structural steels that are of importance
in design and construction. Designers should be familiar with these properties so that they
can select the most economical combination of suitable steels for each application and use
the materials efficiently and safely.
In accordance with contemporary practice, the steels described in this section are given
the names of the corresponding specifications of ASTM, 100 Barr Harbor Dr., West Conshohocken, PA, 19428. For example, all steels covered by ASTM A588, ‘‘Specification for
High-strength Low-alloy Structural Steel,’’ are called A588 steel.

1.1

STRUCTURAL STEEL SHAPES AND PLATES
Steels for structural uses may be classified by chemical composition, tensile properties, and
method of manufacture as carbon steels, high-strength low-alloy steels (HSLA), heat-treated
carbon steels, and heat-treated constructional alloy steels. A typical stress-strain curve for a
steel in each classification is shown in Fig. 1.1 to illustrate the increasing strength levels
provided by the four classifications of steel. The availability of this wide range of specified
minimum strengths, as well as other material properties, enables the designer to select an
economical material that will perform the required function for each application.
Some of the most widely used steels in each classification are listed in Table 1.1 with
their specified strengths in shapes and plates. These steels are weldable, but the welding
materials and procedures for each steel must be in accordance with approved methods. Welding information for each of the steels is available from most steel producers and in
publications of the American Welding Society.

1.1.1

Carbon Steels

A steel may be classified as a carbon steel if (1) the maximum content specified for alloying
elements does not exceed the following: manganese—1.65%, silicon—0.60%, copper—
1.1


1.2

SECTION ONE

FIGURE 1.1 Typical stress-strain curves for structural steels. (Curves have
been modified to reflect minimum specified properties.)

0.60%; (2) the specified minimum for copper does not exceed 0.40%; and (3) no minimum
content is specified for other elements added to obtain a desired alloying effect.
A36 steel is the principal carbon steel for bridges, buildings, and many other structural
uses. This steel provides a minimum yield point of 36 ksi in all structural shapes and in
plates up to 8 in thick.
A573, the other carbon steel listed in Table 1.1, is available in three strength grades for
plate applications in which improved notch toughness is important.
1.1.2

High-Strength Low-Alloy Steels

Those steels which have specified minimum yield points greater than 40 ksi and achieve that
strength in the hot-rolled condition, rather than by heat treatment, are known as HSLA steels.
Because these steels offer increased strength at moderate increases in price over carbon steels,
they are economical for a variety of applications.
A242 steel is a weathering steel, used where resistance to atmospheric corrosion is of
primary importance. Steels meeting this specification usually provide a resistance to atmospheric corrosion at least four times that of structural carbon steel. However, when required,

steels can be selected to provide a resistance to atmospheric corrosion of five to eight times
that of structural carbon steels. A specified minimum yield point of 50 ksi can be furnished
in plates up to 3⁄4 in thick and the lighter structural shapes. It is available with a lower yield
point in thicker sections, as indicated in Table 1.1.
A588 is the primary weathering steel for structural work. It provides a 50-ksi yield point
in plates up to 4 in thick and in all structural sections; it is available with a lower yield point
in thicker plates. Several grades are included in the specification to permit use of various
compositions developed by steel producers to obtain the specified properties. This steel provides about four times the resistance to atmospheric corrosion of structural carbon steels.


PROPERTIES OF STRUCTURAL STEELS AND EFFECTS OF STEELMAKING AND FABRICATION

1.3

TABLE 1.1 Specified Minimum Properties for Structural Steel Shapes and Plates*

ASTM
designation
A36

Plate-thickness
range, in
8 maximum
over 8

A573
Grade 58
Grade 65
Grade 70

11⁄2 maximum
11⁄2 maximum
11⁄2 maximum

Elongation, %

ASTM
group for
structural
shapes†

Yield
stress,
ksi‡

Tensile
strength,
ksi‡

In 2
in§

In
8 in

1–5
1–5

36
32

58–80
58–80

23–21
23

20
20

‫ن‬
‫ن‬
‫ن‬

32
35
42

58–71
65–77
70–90

24
23
21

21
20
18

High-strength low-alloy steels
3
⁄4 maximum
Over 3⁄4 to 11⁄2 max
Over 11⁄2 to 4 max
4 maximum
Over 4 to 5 max
Over 5 to 8 max

A242

A588

A572
Grade
Grade
Grade
Grade
A992

42
50
60
65

6 maximum
4 maximum
11⁄4 maximum
11⁄4 maximum
‫ن‬

1 and 2
3
4 and 5
1–5
1–5
1–5

50
46
42
50
46
42

70
67
63
70
67
63

21
21
21
21
21
21

18

18
18
18
—
—

1–5
1–5
1–3
1–3
1–5

42
50
60
65
50–65

60
65
75
80
65

24
21
18
17
21

20
18
16
15
18

Heat-treated carbon and HSLA steels
A633
Grade A
Grade C, D
Grade E
A678
Grade A
Grade B
Grade C
Grade D
A852
A913

4 maximum
21⁄2 maximum
Over 21⁄2 to 4 max
4 maximum
Over 4 to 6 max

‫ن‬
‫ن‬
‫ن‬
‫ن‬
‫ن‬

42
50
46
60
55

63–83
70–90
65–85
80–100
75–95

23
23
23
23
23

18
18
18
18
18

11⁄2 maximum
21⁄2 maximum
3
⁄4 maximum
Over 3⁄4 to 11⁄2 max

Over 11⁄2 to 2 max
3 maximum
4 maximum

‫ن‬
‫ن‬
‫ن‬
‫ن‬
‫ن‬
‫ن‬

‫ن‬
‫ن‬
‫ن‬
‫ن‬

1–5
1–5
1–5
1–5

50
60
75
70
65
75
70
50
60

65
70

70–90
80–100
95–115
90–110
85–105
90–110
90–110
65
75
80
90

22
22
19
19
19
18
19
21
18
17
16

—
—
—

—
—
—
—
18
16
15
14

‫ن‬


1.4

SECTION ONE

TABLE 1.1 Specified Minimum Properties for Structural Steel Shapes and Plates* (Continued )

ASTM
designation

Plate-thickness
range, in

ASTM
group for
structural
shapes†

Elongation, %

Yield
stress,
ksi‡

Tensile
strength,
ksi‡

In 2
in§

In
8 in

110–130
100–130

18
16

—
—

Heat-treated constructional alloy steels
A514

21⁄2 maximum
Over 21⁄2 to 6 max

‫ن‬

‫ن‬

100
90

* The following are approximate values for all the steels:
Modulus of elasticity—29 ϫ 103 ksi.
Shear modulus—11 ϫ 103 ksi.
Poisson’s ratio—0.30.
Yield stress in shear—0.57 times yield stress in tension.
Ultimate strength in shear—2⁄3 to 3⁄4 times tensile strength.
Coefficient of thermal expansion—6.5 ϫ 10Ϫ6 in per in per deg F for temperature range Ϫ50 to ϩ150ЊF.
Density—490 lb / ft3.
† See ASTM A6 for structural shape group classification.
‡ Where two values are shown for yield stress or tensile strength, the first is minimum and the second is maximum.
§ The minimum elongation values are modified for some thicknesses in accordance with the specification for the
steel. Where two values are shown for the elongation in 2 in, the first is for plates and the second for shapes.
‫ ن‬Not applicable.

These relative corrosion ratings are determined from the slopes of corrosion-time curves
and are based on carbon steels not containing copper. (The resistance of carbon steel to
atmospheric corrosion can be doubled by specifying a minimum copper content of 0.20%.)
Typical corrosion curves for several steels exposed to industrial atmosphere are shown in
Fig. 1.2.
For methods of estimating the atmospheric corrosion resistance of low-alloy steels based
on their chemical composition, see ASTM Guide G101. The A588 specification requires that
the resistance index calculated according to Guide 101 shall be 6.0 or higher.
A588 and A242 steels are called weathering steels because, when subjected to alternate
wetting and drying in most bold atmospheric exposures, they develop a tight oxide layer
that substantially inhibits further corrosion. They are often used bare (unpainted) where the

oxide finish that develops is desired for aesthetic reasons or for economy in maintenance.
Bridges and exposed building framing are typical examples of such applications. Designers
should investigate potential applications thoroughly, however, to determine whether a weathering steel will be suitable. Information on bare-steel applications is available from steel
producers.
A572 specifies columbium-vanadium HSLA steels in four grades with minimum yield
points of 42, 50, 60, and 65 ksi. Grade 42 in thicknesses up to 6 in and grade 50 in
thicknesses up to 4 in are used for welded bridges. All grades may be used for riveted or
bolted construction and for welded construction in most applications other than bridges.
A992 steel was introduced in 1998 as a new specification for rolled wide flange shapes
for building framing. It provides a minimum yield point of 50 ksi, a maximum yield point
of 65 ksi, and a maximum yield to tensile ratio of 0.85. These maximum limits are considered
desirable attributes for seismic design. To enhance weldability, a maximum carbon equivalent
is also included, equal to 0.47% for shape groups 4 and 5 and 0.45% for other groups. A
supplemental requirement can be specified for an average Charpy V-notch toughness of 40
ft ⅐ lb at 70ЊF.


PROPERTIES OF STRUCTURAL STEELS AND EFFECTS OF STEELMAKING AND FABRICATION

1.5

FIGURE 1.2 Corrosion curves for structural steels in an industrial atmosphere. (From R. L.
Brockenbrough and B. G. Johnston, USS Steel Design Manual, R. L. Brockenbrough & Associates,
Inc., Pittsburgh, Pa., with permission.)

1.1.3

Heat-Treated Carbon and HSLA Steels

Both carbon and HSLA steels can be heat treated to provide yield points in the range of 50

to 75 ksi. This provides an intermediate strength level between the as-rolled HSLA steels
and the heat-treated constructional alloy steels.
A633 is a normalized HSLA plate steel for applications where improved notch toughness
is desired. Available in four grades with different chemical compositions, the minimum yield
point ranges from 42 to 60 ksi depending on grade and thickness.
A678 includes quenched-and-tempered plate steels (both carbon and HSLA compositions)
with excellent notch toughness. It is also available in four grades with different chemical
compositions; the minimum yield point ranges from 50 to 75 ksi depending on grade and
thickness.
A852 is a quenched-and-tempered HSLA plate steel of the weathering type. It is intended
for welded bridges and buildings and similar applications where weight savings, durability,
and good notch toughness are important. It provides a minimum yield point of 70 ksi in
thickness up to 4 in. The resistance to atmospheric corrosion is typically four times that of
carbon steel.
A913 is a high-strength low-allow steel for structural shapes, produced by the quenching
and self-tempering (QST) process. It is intended for the construction of buildings, bridges,
and other structures. Four grades provide a minimum yield point of 50 to 70 ksi. Maximum
carbon equivalents to enhance weldability are included as follows: Grade 50, 0.38%; Grade
60, 0.40%; Grade 65, 0.43%; and Grade 70, 0.45%. Also, the steel must provide an average
Charpy V-notch toughness of 40 ft ⅐ lb at 70ЊF.
1.1.4

Heat-Treated Constructional Alloy Steels

Steels that contain alloying elements in excess of the limits for carbon steel and are heat
treated to obtain a combination of high strength and toughness are termed constructional


1.6

SECTION ONE

alloy steels. Having a yield strength of 100 ksi, these are the strongest steels in general
structural use.
A514 includes several grades of quenched and tempered steels, to permit use of various
compositions developed by producers to obtain the specified strengths. Maximum thickness
ranges from 11⁄4 to 6 in depending on the grade. Minimum yield strength for plate thicknesses
over 21⁄2 in is 90 ksi. Steels furnished to this specification can provide a resistance to atmospheric corrosion up to four times that of structural carbon steel depending on the grade.
Constructional alloy steels are also frequently selected because of their ability to resist
abrasion. For many types of abrasion, this resistance is related to hardness or tensile strength.
Therefore, constructional alloy steels may have nearly twice the resistance to abrasion provided by carbon steel. Also available are numerous grades that have been heat treated to
increase the hardness even more.

1.1.5

Bridge Steels

Steels for application in bridges are covered by A709, which includes steel in several of the
categories mentioned above. Under this specification, grades 36, 50, 70, and 100 are steels
with yield strengths of 36, 50, 70, and 100 ksi, respectively. (See also Table 11.28.)
The grade designation is followed by the letter W, indicating whether ordinary or high
atmospheric corrosion resistance is required. An additional letter, T or F, indicates that
Charpy V-notch impact tests must be conducted on the steel. The T designation indicates
that the material is to be used in a non-fracture-critical application as defined by AASHTO;
the F indicates use in a fracture-critical application.
A trailing numeral, 1, 2, or 3, indicates the testing zone, which relates to the lowest
ambient temperature expected at the bridge site. (See Table 1.2.) As indicated by the first
footnote in the table, the service temperature for each zone is considerably less than the
Charpy V-notch impact-test temperature. This accounts for the fact that the dynamic loading
rate in the impact test is more severe than that to which the structure is subjected. The

toughness requirements depend on fracture criticality, grade, thickness, and method of connection.
A709-HPS70W, designated as a High Performance Steel (HPS), is also now available for
highway bridge construction. This is a weathering plate steel, designated HPS because it
possesses superior weldability and toughness as compared to conventional steels of similar
strength. For example, for welded construction with plates over 21⁄2 in thick, A709-70W
must have a minimum average Charpy V-notch toughness of 35 ft ⅐ lb at Ϫ10ЊF in Zone III,
the most severe climate. Toughness values reported for some heats of A709-HPS70W have
been much higher, in the range of 120 to 240 ft ⅐ lb at Ϫ10ЊF. Such extra toughness provides
a very high resistance to brittle fracture.
(R. L. Brockenbrough, Sec. 9 in Standard Handbook for Civil Engineers, 4th ed., F. S.
Merritt, ed., McGraw-Hill, Inc., New York.)

1.2

STEEL-QUALITY DESIGNATIONS
Steel plates, shapes, sheetpiling, and bars for structural uses—such as the load-carrying
members in buildings, bridges, ships, and other structures—are usually ordered to the requirements of ASTM A6 and are referred to as structural-quality steels. (A6 does not
indicate a specific steel.) This specification contains general requirements for delivery related
to chemical analysis, permissible variations in dimensions and weight, permissible imperfections, conditioning, marking and tension and bend tests of a large group of structural
steels. (Specific requirements for the chemical composition and tensile properties of these