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TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2010 www.TRB.org N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP REPORT 645 Subject Areas Bridges, Other Structures, and Hydraulics and Hydrology ⢠Security Blast-Resistant Highway Bridges: Design and Detailing Guidelines Eric B. Williamson Oguzhan Bayrak G. Daniel Williams Carrie E. Davis UNIVERSITY OF TEXAS AT AUSTIN Austin, TX Kirk A. Marchand Aldo E. McKay PROTECTION ENGINEERING CONSULTANTS Dripping Springs, TX John Kulicki Wagdy Wassef MODJESKI AND MASTERS, INC. Mechanicsburg, PA Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Boardâs recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs. Published reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: http://www.national-academies.org/trb/bookstore Printed in the United States of America NCHRP REPORT 645 Project 12-72 ISSN 0077-5614 ISBN 978-0-309-11819-4 Library of Congress Control Number 2009944223 © 2010 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the National Cooperative Highway Research Program conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. Such approval reflects the Governing Boardâs judgment that the program concerned is of national importance and appropriate with respect to both the purposes and resources of the National Research Council. The members of the technical committee selected to monitor this project and to review this report were chosen for recognized scholarly competence and with due consideration for the balance of disciplines appropriate to the project. The opinions and conclusions expressed or implied are those of the research agency that performed the research, and, while they have been accepted as appropriate by the technical committee, they are not necessarily those of the Transportation Research Board, the National Research Council, the American Association of State Highway and Transportation Officials, or the Federal Highway Administration, U.S. Department of Transportation. Each report is reviewed and accepted for publication by the technical committee according to procedures established and monitored by the Transportation Research Board Executive Committee and the Governing Board of the National Research Council. The Transportation Research Board of the National Academies, the National Research Council, the Federal Highway Administration, the American Association of State Highway and Transportation Officials, and the individual states participating in the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names appear herein solely because they are considered essential to the object of this report.
CRP STAFF FOR NCHRP REPORT 645 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs David B. Beal, Senior Program Officer, Retired Waseem Dekelbab, Senior Program Officer Eileen P. Delaney, Director of Publications Doug English, Editor NCHRP PROJECT 12-72 PANEL Field of DesignâArea of Bridges George A. Christian, New York State DOT, Albany, NY (Chair) John A. Bryson, Parsons Brinckerhoff Quade & Douglas, Inc., New York, NY Shyam Gupta, Columbia, MO Sophia Hassiotis, Stevens Institute of Technology, Hoboken, NJ Jugesh Kapur, Washington State DOT, Olympia, WA Richard D. Land, California DOT, Sacramento, CA Thomas Rummel, Texas DOT, Austin, TX Jonathan C. Van Hook, Florida DOT, Tallahassee, FL David G. Winget, U.S. Army Theodore P. Zoli, III, HNTB Corporation, New York, NY Sheila Rimal Duwadi, FHWA Liaison Stephen F. Maher, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed for NCHRP Project 12-72 under the supervision of Dr. Eric B. Williamson, Associate Professor of Civil Engineering at the University of Texas at Austin (UT), who served as the project Principal Investigator. Dr. Oguzhan Bayrak, Associate Professor of Civil Engineering at UT, Kirk A. Marchand, Managing Principal of Protection Engineering Consultants (PEC), Dripping Springs, Texas, and Dr. John Kulicki, President/CEO and Chief Engineer of Modjeski and Masters, Inc. (M&M), Mechanicsburg, Pennsylva- nia, served as co-Principal Investigators. Other researchers included G. Daniel Williams, Graduate Research Assistant and Ph.D. Candidate at UT, and Carrie E. Davis, Graduate Research Assistant and M.S. Candidate at UT. Additional contributors included Aldo E. McKay, Project Engineer with PEC, James C. Ray, Research Engineer at the U.S. Army Corps of Engineers, Vicksburg, Mississippi, and Wagdy G. Wassef, Senior Associate at M&M. C O O P E R A T I V E R E S E A R C H P R O G R A M S
This report presents code-ready language containing general design guidance and a sim- plified design procedure for blast-resistant reinforced concrete bridge columns. It provides the results of experimental blast tests and analytical research on reinforced concrete bridge columns intended to investigate the effectiveness of a variety of different design techniques. The material in this report will be of immediate interest to bridge designers. There is a need to protect the nationâs bridges from intentional or accidental explosions. The impacts of these loads on buildings and military structures have been studied for many years, but design for resistance to explosive effects is a new area for bridge engineers. Much research and development has been done on the effectiveness of seismic strengthening details for buildings and bridges, and it has been suggested that these or similar bridge details, used in new construction or as a retrofit, may serve also to resist explosions and pro- vide a predictable level of protection. There is a need to meld knowledge of seismic and extreme-event design for new and existing structures with the equally well-known field of blast-resistant design and the relatively new field of highway bridge blast-resistant design. Under NCHRP Project 12-72, the research team was selected to develop design and detailing guidelines for improving the structural performance and resistance to explosive effects for new and existing bridges. This research was performed under NCHRP Project 12-72 by the University of Texas at Austin with the assistance of Protection Engineering Consultants and Modjeski and Mas- ters, Inc. The report fully documents the research leading to the developed design and detailing guidelines for blast-resistant reinforced concrete bridge columns. F O R E W O R D By Waseem Dekelbab Staff Officer Transportation Research Board
C O N T E N T S 1 Summary 4 Chapter 1 Introduction 4 1.1 Overview 5 1.2 Background and History 7 1.3 Research Approach 8 Chapter 2 Research Background 8 2.1 Overview 8 2.2 Literature Review 8 2.2.1 Blast Loads and Shock Phenomena 13 2.2.2 Structural Response to Blast Loads 13 2.2.3 Dynamic Material Strength and Strain-Rate Effects 15 2.2.4 Application of Seismic Design to Blast-Loaded Bridges 18 2.2.5 Design Issues 24 2.3 Research Needs 24 2.3.1 Research Needs and Focus of Current Study 25 2.3.2 Blast-Resistant Design: Buildings versus Bridges 26 2.3.3 Current and Past Research on Highway Bridges 28 2.3.4 Summary 28 2.4 Focus of Current Work 30 Chapter 3 Experimental Program 30 3.1 Overview 30 3.2 Phase I Load Characterization Study 30 3.2.1 Experimental Setup 31 3.2.2 Data Acquisition and Instrumentation Plan 31 3.3 Phase II Response Test 33 3.3.1 Background on Parameters Selected for Testing 37 3.3.2 Column Design 41 3.3.3 Reaction Structure Design 41 3.3.4 Data Acquisition and Instrumentation Plan 43 3.3.5 Column Construction 43 3.3.6 Small Standoff Test Setup 44 3.3.7 Spall/Breach Test Setup 45 3.4 Summary 46 Chapter 4 Analytical Research Program 46 4.1 Overview 46 4.2 Current State-of-Practice: SDOF 49 4.3 Simplified Modeling and Software 49 4.3.1 Load Prediction Techniques 50 4.3.2 Response Prediction 55 4.3.3 Advanced Modeling Methods and Software
60 Chapter 5 Observations and Research Findings 60 5.1 Overview 60 5.1.1 Phase I Tests 65 5.1.2 Phase II Tests 83 5.2 Observations from Analytical Programs 83 5.2.1 Strain Data 83 5.2.2 Actual Boundary Conditions 85 5.2.3 Actual Load Distribution 87 5.3 Summary 88 Chapter 6 Design and Detailing Guidelines 88 6.1 Overview 88 6.2 Risk Assessment Guidelines for Bridges 89 6.3 Blast-Load Guidelines 90 6.4 Design and Detailing Guidelines for Columns 91 6.4.1 Design Category A 92 6.4.2 Design Category B 92 6.4.3 Design Category C 97 6.5 Analysis Guidelines for Columns 99 6.6 Summary 100 Chapter 7 Analysis Guidelines 100 7.1 Overview 100 7.2 Simplified Analyses Guidelines 102 7.3 Airblast Modeling Using Computation Fluid Dynamics 105 7.4 Concrete Modeling 106 7.5 Coupled Analyses 107 7.6 Summary 108 Chapter 8 Design Examples 108 8.1 Overview 108 8.2 Design Examples 109 8.2.1 Design Example 1 115 8.2.2 Design Example 2 123 8.2.3 Design Example 3 129 8.2.4 Design Example 4 133 8.3 Summary 134 Chapter 9 Summary, Conclusions, and Recommendations 134 9.1 Summary of Research Program 135 9.2 Conclusions and Recommendations 135 9.2.1 Summary of Small Standoff Blast Tests 135 9.2.2 Summary of Local Damage Tests 135 9.2.3 Summary of Design Guidelines 136 9.3 Recommendations for Future Work 138 References 141 List of Variables
