Bridges

Ernest Sternberg, George C. Lee

Description

Whether you are a student considering a career in civil engineering and transportation planning, a public official interested in the future of infrastructure, or a person who simply cares about bridges, this book offers an accessible and illustrated introduction to the most beloved feature of our built environment. Learn about engineering basics: the forces that bridges must resist to stay aloft and the principles by which engineers decide which types of bridges make sense at which sites. Find out how engineers protect bridges from their greatest threats—the earthquakes, floods, and other hazards that can cause catastrophic damage.

Moving from engineering to planning, learn how we decide whether a bridge is worth building in the first place, learn about controversial features of cost-benefit analysis, and about the transportation models by which planners forecast bridge effects on traffic patterns. Investigate a sometimes intractable problem: why a project often creeps along for a decade or more to get from initial studies to the day the ribbon is cut, undergoing vast cost escalations. Also explore the environmental impact of bridges, and the meaning of a "sustainable bridge," and whether bridges could once again be built, like ancient Roman ones, to last a thousand years.
List of Tables and Figures
Preface and Acknowledgments

Part I: Deciding about Bridges

1. Crossing the Bridge before We Get There

2. Counting Our Bridges

Part II: Bridge Engineering

3. Understanding Stresses and Strains

4. Bridge Types and Sites

5. Making Strong Bridges: Dealing with Uncertainty

6. Resisting Extreme Events

Part III: Bridge Planning

7. Is It Worth It? Costs, Benefits, and Tough Decisions

8. Traffic across the Bridge

9. The Bridge in the Environment

10. Delivering the Bridge

Part IV: Conclusion

11. A Bridge Spanning a Millennium

Index

Sujets

• Sciences appliquées
• Ingénierie
• Sciences appliquées
• Sciences appliquées
• Ingénierie
• Architecture
• Bridges

Informations

• Publié par: State University of New York Press
• Date de parution: 23 février 2015
• Nombre de lectures: 0
• EAN13: 9781438455273
• Langue: English

Extrait

BRIDGES
their engineering and planning
including engineering basics, structures that keep them up, hazards that threaten them, uses in transportation, roles as American infrastructure, costs and evaluation, environmental effects and sustainability, and challenges of on-time delivery
George C. Lee and Ernest Sternberg
Illustrated by
David C. Pierro
Published by
S TATE U NIVERSITY OF N EW Y ORK P RESS , A LBANY
© 2015 State University of New York
All rights reserved
Printed in the United States of America
No part of this book may be used or reproduced in any manner whatsoever without written permission. No part of this book may be stored in a retrieval system or transmitted in any form or by any means including electronic, electrostatic, magnetic tape, mechanical, photocopying, recording, or otherwise without the prior permission in writing of the publisher.
For information, contact State University of New York Press, Albany, NY www.sunypress.edu
Production, Laurie D. Searl Marketing, Anne M. Valentine
Library of Congress Cataloging-in-Publication Data
Lee, George C.
Bridges : their engineering and planning / George C. Lee and Ernest Sternberg ; Illustrated by David C. Pierro.
pages cm
Includes bibliographical references and index.
ISBN 978-1-4384-5525-9 (hardcover : alk. paper)
ISBN 978-1-4384-5526-6 (pbk. : alk. paper)
ISBN 978-1-4384-5527-3 (ebook)
1. Bridges—Design and construction. 2. Bridges—Planning. I. Sternberg, Ernest, 1953– II. Title. TG300.L44 2015 624.2—dc23 2014013135
10 9 8 7 6 5 4 3 2 1
In loving memory of Grace S. Lee, to whom I owe all my accomplishments, and who always cared about the education of students. from George
To cousin Kati, of blessed memory, who was killed in 1944 or 1945 when very young, and could have become a builder of bridges. from Ernie
CONTENTS

LIST OF TABLES AND FIGURES
PREFACE AND ACKNOWLEDGMENTS
PART I: DECIDING ABOUT BRIDGES
CHAPTER ONE
Crossing the Bridge before We Get There
CHAPTER TWO
Counting Our Bridges
PART II: BRIDGE ENGINEERING
CHAPTER THREE
Understanding Stresses and Strains
CHAPTER FOUR
Bridge Types and Sites
CHAPTER FIVE
Making Strong Bridges: Dealing with Uncertainty
CHAPTER SIX
Resisting Extreme Events
PART III: BRIDGE PLANNING
CHAPTER SEVEN
Is It Worth It? Costs, Benefits, and Tough Decisions
CHAPTER EIGHT
Traffic across the Bridge
CHAPTER NINE
The Bridge in the Environment
CHAPTER TEN
Delivering the Bridge
PART IV: CONCLUSION
CHAPTER ELEVEN
A Bridge Spanning a Millennium
INDEX
TABLES AND FIGURES
TABLES Table 2.1 U.S. Bridges by Length of Main Span, 2011 Table 2.2 Which metro areas have the most bridges? Ranked by bridges per 100,000 population, 2010 Table 2.3 Public Bridges in the United States, 1992–2011 Table 2.4 Deficiency in Bridges, 2011 Table 2.5 Trends in Deficient Bridges Table 2.6 Bridge Building by Year Table 6.1 Causes of Bridge Failure, United States, 1980–2012 Table 7.1 Recommended Standard Values for Vehicle Operation, State of Minnesota Table 7.2 Costs and Benefits of a New Bridge in Constant $1000 Table 7.3 Net Present Value ($ millions) of New Bridge Under Alternative Scenarios and Discount Rates Table 7.4 Costs and Benefits of Long-Lasting New Bridge in Constant $1000 Table 8.1 Four bridge congestion scenarios for Square City during peak traffic hour Table 10.1 Stages in a Major Public Projects in the United States FIGURES Figure 2.1 US Bridges in 2010 by Decade of Completion. Figure 2.2 Trends in Travel by Metro Size. Figure 3.1 A 100-kip load imposes more stress (causing strain) on the thinner cylinder. Figure 3.2 Beyond a column’s ultimate strength, the load causes buckling in the tall column, but crushing in the short column. Figure 3.3 Larger loads impose greater tensile strain. Figure 3.4 From original size (0), the cable stretches proportionately to applied stress, until yield stress (A). Beyond that threshold, the cable deforms permanently (B), and eventually snaps (C). Figure 3.5 Terms for a beam’s three dimensions, from an observer’s point of view. Figure 3.6 (A) Shear forces applied to a component. (B) Shear strain experienced by a beam at its juncture with a column. Figure 3.7 Under bending, the imaginary cubes at the beam’s upper surface are stretched apart (undergo tension), and at the lower surface get pushed together (are compressed). Figure 3.8 Cylinder undergoing torsion at its free end. Figure 3.9 Actual bending on a beam bridge includes normal bending (compression on the upper surface, tension on the lower) and shear. Figure 3.10 Effects of bending moment, shown by live loads of equal weight applied to ever longer cantilevers. Figure 4.1 Cross sections of reinforced concrete beam (left), steel box beam (middle), and steel I-beam (right). Figure 4.2 Slab bridge. Figure 4.3 Viaduct. Figure 4.4 Girder bridge. Figure 4.5 A simple stone arch bridge. Figure 4.6 A through-arch and a deck arch. Figure 4.7 Truss bridge. Figure 4.8 Suspension bridge. Figure 4.9 Cable-stayed bridge. Figure 4.10 Tower shapes. Figure 4.11 Piers—footings and foundations. Figure 5.1A A three-span steel girder bridge viewed from the side. Figure 5.1B The same bridge viewed in cross section, revealing a two-column pier, the columns connected with a cap beam, on which five girders rest, supporting the deck. Figure 5.2 A model truck for estimating bridge loads. Figure 5.3 Load (Q) and resistance (R) curves, shown on the same plot. Figure 5.4 Reliability curve, also known as the failure probability curve. Failure probability is shown in the striped area to the left of the Y-axis. Figure 6.1 Bridge span unseated by longitudinal shaking. Figure 6.2 A viscous damper and elastomeric bearing connecting a girder bridge to its abutment. Figure 6.3 Scouring at a bridge. Figure 6.4 Scour wears away soils at the bridge foundation. Figure 6.5 Riprap to reduce erosion and scour at bridge. Figure 6.6 Ways a vessel can collide with a bridge. Figure 8.1 The Cross-Bronx Expressway, the nation’s most traffic-choked highway. Figure 8.2 Square City divided into Transportation Analysis Zones. Figure 8.3 Average traffic speed (in each direction) on Old Bridge during peak travel hour. Figure 9.1 Bridge Proposals for “Harbor Bridge” in Great Lake City. Figure 10.1 Upper: The twin-span Cattaraugus Creek Bridge, carrying Route 219, an expressway in upstate New York. Lower: A view of the Kosciuszko Bridge on the Brooklyn-Queens Expressway in New York City, taken October 2010.
PREFACE AND ACKNOWLEDGMENTS

As we worked on our book, we consulted with Mr. Myint Lwin, director of the Office of Bridge Technology at the US Federal Highway Administration (FHWA). He told us of the two most serious challenges facing the highway system and bridges in particular. The first is the need for properly educated new professionals who can effectively design and manage the renewal of our aging system. The second is communication with the general public and with elected representatives, to make them aware that infrastructure investments require long-term commitment and the steady flow of resources.
We hope our book plays a part in answering both these challenges. We intend it to inspire students in search of satisfying careers to take up the study of bridge engineering and infrastructure planning. And we wish it to inform citizens and public officials about what their community will face when it decides whether to build or replace a bridge, and if it actually commits to doing so, the many complex tasks through which the project will be brought to completion. Oh yes, we are very glad to have as a reader anyone who is just curious. We are proud that over the course of our writing, and with assistance from the FHWA, our university has also established a master’s degree program in bridge engineering, which is already graduating a new generation ready to face the future of aging infrastructure.
This writing project has received partial financial support from the FHWA (DTFH61-08-C-00012), the National Science Foundation PAESMEN Individual Award (DUE0627385), the University at Buffalo Samuel P. Capen endowment fund, and MCEER, the multidisciplinary center for research on earthquakes and extreme events. To them we express our sincere gratitude.
The writing of an interdisciplinary book on bridges, by two authors with different backgrounds, one in structural engineering and one in urban planning, has depended on open dialog between us. With much discussion and with growing friendship we did indeed find the basis for mutually understanding complex topics well enough to put them into words we could each appreciate. We hope we have thereby been able to provide clear, well-rounded explanations to our readers.
Our ability to write this book has also depended on advice and assistance from friends, students, colleagues, and bridge-engineering professionals. Mr. Srikanth Akula did extensive analysis for us on American bridges ( chapter 2 ), and later so did Mr. Sanket T. Dhatkar, who brought the analysis up to date. This effort was quite necessary because of the National Bridge Inventory’s great complexity. We are obligated to Mr. Jerome O’Connor for his insistence that we redouble our efforts to make sure we had interpreted the inventory well, for his careful review of our chapter on bridge delivery, and for his suggestions for photographs.
Ms. Nasi Zhang helped us analyze and provide technically correct illustration of stresses and strains in a typical bridge under applied forces, helping bring chapters 5 and 6 to their present state, in which we strive for them to be accessible while remaining technically respectable. For chapter 9 , to illustrate how planners analyze auto traffic for decisions about needs for a bridge, we hypothesized a simple place called Square City. The software with which we analyze Square City is known as “DynusT.” We are grateful to Mr. Jinge Hu and Professor Qian Wang for developing the Square Ci