Table Of ContentDesign and Construction of
Modern Steel Railway Bridges
Design and Construction of
Modern Steel Railway Bridges
Second Edition
By
John F. Unsworth
CRC Press
Taylor & Francis Group
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Library of Congress Cataloging-in-Publication Data
Names: Unsworth, John F.
Title: Design and construction of modern steel railway bridges, / John F.
Unsworth.
Description: Second edition. | Boca Raton : Taylor & Francis, CRC Press,
2017. | Includes bibliographical references and index.
Identifiers: LCCN 2017006499| ISBN 9781498734103 (hardback) | ISBN
9781315120775 (ebk)
Subjects: LCSH: Railroad bridges--Design and construction. | Iron and steel
bridges.
Classification: LCC TG445 .U57 2017 | DDC 624.2-- dc23
LC record available at https://lccn.loc.gov/2017006499
Visit the Taylor & Francis Web site at
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and the CRC Press Web site at
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Dedication
To my extraordinary wife, Elizabeth, whose steadfast support and patience
made this book and most other good things in my life possible.
Contents
Acknowledgment .............................................................................................................................xv
Preface to the Second Edition ........................................................................................................xvii
Author ............................................................................................................................................xix
Chapter 1 History and Development of Steel Railway Bridges ....................................................1
1.1 Introduction .......................................................................................................1
1.2 Iron Railway Bridges .........................................................................................2
1.2.1 Cast Iron Construction .........................................................................2
1.2.2 Wrought Iron Construction ..................................................................8
1.3 Steel Railway Bridges ......................................................................................23
1.4 T he Development of Railway Bridge Engineering .........................................31
1.4.1 Strength of Materials and Structural Mechanics ...............................31
1.4.2 Railway Bridge Design Specifications ...............................................32
1.4.3 Modern Steel Railway Bridge Design ................................................34
Bibliography ...............................................................................................................36
Chapter 2 Steel for Modern Railway Bridges .............................................................................39
2.1 I ntroduction .....................................................................................................39
2.2 M anufacture of Structural Steel ......................................................................39
2.3 E ngineering Properties of Steel .......................................................................42
2.3.1 Strength ..............................................................................................42
2.3.1.1 Elastic Yield Strength of Steel ............................................42
2.3.1.2 Fatigue Strength of Steel ....................................................44
2.3.2 Ductility..............................................................................................45
2.3.3 Fracture Resistance ............................................................................45
2.3.4 Weldability .........................................................................................46
2.3.5 Corrosion Resistance ..........................................................................46
2.4 Types of Structural Steel .................................................................................47
2.4.1 Carbon Steels .....................................................................................47
2.4.2 High-Strength Low-Alloy Steels ........................................................47
2.4.3 Heat-Treated Low-Alloy Steels ..........................................................48
2.4.4 High-Performance Steels ...................................................................48
2.5 Structural Steel for Railway Superstructures ..................................................49
2.5.1 Material Properties .............................................................................49
2.5.2 Structural Steel for Modern North American Railway
Superstructures ...................................................................................50
References ..................................................................................................................54
Chapter 3 Planning and Preliminary Design of Modern Steel Railway Bridges .......................55
3.1 Introduction .....................................................................................................55
3.2 P lanning of Railway Bridges ...........................................................................56
3.2.1 Bridge Crossing Economics ...............................................................56
3.2.2 Railroad Operating Requirements .....................................................57
vii
viii Contents
3.2.3 Site Conditions (Public and Technical Requirements of Bridge
Crossings) ...........................................................................................58
3.2.3.1 Regulatory Requirements ...................................................58
3.2.3.2 Hydrology and Hydraulics of the Bridge Crossing .............58
3.2.3.3 Highway, Railway, and Marine Clearances ........................69
3.2.3.4 Geotechnical Conditions ....................................................69
3.2.4 Geometry of the Track and Bridge .....................................................70
3.2.4.1 Horizontal Geometry of the Bridge ....................................71
3.2.4.2 Vertical Geometry of the Bridge ........................................82
3.3 Preliminary Design of Steel Railway Bridges.................................................82
3.3.1 Bridge A Esthetics ..............................................................................82
3.3.2 Steel Railway Bridge Superstructures ................................................83
3.3.2.1 Bridge Decks for Steel Railway Bridges ............................84
3.3.2.2 Bridge Framing Details ......................................................87
3.3.2.3 Bridge Bearings ..................................................................88
3.3.3 Bridge Stability ..................................................................................90
3.3.4 Pedestrian Walkways .........................................................................90
3.3.5 General Design Criteria .....................................................................91
3.3.5.1 Structural Analysis for Modern Steel Superstructure
Design .................................................................................91
3.3.5.2 Structural Design for Modern Steel Superstructure
Fabrication ..........................................................................92
3.3.6 Fabrication Considerations ...............................................................100
3.3.7 Erection Considerations ...................................................................102
3.3.8 Detailed Design of the Superstructure .............................................102
References ................................................................................................................102
Chapter 4 Loads and Forces on Steel Railway Bridges ............................................................105
4.1 Introduction ...................................................................................................105
4.2 Dead Loads ....................................................................................................105
4.3 Railway Live Loads .......................................................................................106
4.3.1 Static Freight Train Live Load .........................................................106
4.3.1.1 Cooper’s Design Live Load for Projected Railway
Equipment .........................................................................115
4.3.1.2 Fatigue Design Live Load for Railway Equipment ..........118
4.3.2 Dynamic Freight Train Live Load ...................................................125
4.3.2.1 Rocking and Vertical Dynamic Forces .............................125
4.3.2.2 Design Impact Load..........................................................144
4.3.2.3 Longitudinal Forces due to Traction and Braking ............145
4.3.2.4 Centrifugal Forces ............................................................155
4.3.2.5 Lateral Forces from Moving Freight Equipment ..............159
4.3.3 Distribution of Live Load .................................................................159
4.3.3.1 Distribution of Live Load for Open Deck Steel Bridges ..159
4.3.3.2 Distribution of Live Load for Ballasted Deck Steel
Bridges ..............................................................................160
4.3.3.3 Distribution of Live Load for Direct Fixation Deck
Steel Bridges .....................................................................162
4.4 Environmental and Other Steel Railway Bridge Design Forces ...................164
4.4.1 Wind Forces on Steel Railway Bridges ............................................164
Contents ix
4.4.2 Thermal Forces from Continuous Welded Rail on Steel Railway
Bridges ..............................................................................................170
4.4.2.1 Safe Rail Separation Criteria ............................................172
4.4.2.2 Safe Stress in the CWR to Preclude Buckling .................173
4.4.2.3 Acceptable Relative Displacement between
Rail-to-Deck and Deck-to-Span .......................................175
4.4.2.4 Design for CWR on Steel Railway Bridges ......................186
4.4.3 Seismic Forces on Steel Railway Bridges ........................................187
4.4.3.1 Equivalent Static Lateral Force ........................................187
4.4.3.2 Response Spectrum Analysis of Steel Railway
Superstructures .................................................................188
4.4.4 Loads Relating to Overall Stability of the Superstructure ...............190
4.4.4.1 Derailment Load ...............................................................190
4.4.4.2 Other Loads for Overall Lateral Stability ........................192
4.4.5 Pedestrian Loads ..............................................................................192
4.5 Load and Force Combinations for Design of Steel Railway Superstructures ....193
References ................................................................................................................194
Chapter 5 Structural Analysis and Design of Steel Railway Bridges .......................................197
5.1 Introduction ...................................................................................................197
5.2 Structural Analysis of Steel Railway Superstructures ..................................197
5.2.1 Live Load Analysis of Steel Railway Superstructures .....................197
5.2.1.1 Maximum Shear Force and Bending Moment due to
Moving Concentrated Loads on Simply Supported
Spans .................................................................................199
5.2.1.2 Influence Lines for Maximum Effects of Moving
Loads on Superstructures .................................................213
5.2.1.3 Equivalent Uniform Loads for Maximum Shear Force
and Bending Moment in Simply Supported Spans ...........234
5.2.1.4 Maximum Shear Force and Bending Moment in
Simply Supported Spans from Equations and Tables .......244
5.2.1.5 Modern Structural Analysis .............................................245
5.2.2 Lateral Load Analysis of Steel Railway Superstructures ................246
5.2.2.1 Lateral Bracing Systems ...................................................246
5.3 Structural Design of Steel Railway Superstructures .....................................260
5.3.1 Failure Modes of Steel Railway Superstructures .............................261
5.3.2 Steel Railway Superstructure Design ...............................................262
5.3.2.1 Strength Design ................................................................262
5.3.2.2 Serviceability Design ........................................................264
5.3.2.3 Other Design Criteria for Steel Railway Bridges .............273
References ................................................................................................................274
Chapter 6 Design of Axial Force Steel Members .....................................................................277
6.1 Introduction ...................................................................................................277
6.2 Axial Tension Members ................................................................................277
6.2.1 Strength of Axial Tension Members ................................................277
6.2.1.1 Net Area, A , of Tension Members ...................................278
n
6.2.1.2 Effective Net Area, A, of Tension Members ....................279
e
6.2.2 Fatigue Strength of Axial Tension Members ...................................282
6.2.3 Serviceability of Axial Tension Members ........................................284
