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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 654 Subscriber Categories Bridges and Other Structures â¢ Highways â¢ Materials Evaluation and Repair Procedures for Precast/Prestressed Concrete Girders with Longitudinal Cracking in the Web Maher K. Tadros UNIVERSITY OF NEBRASKA-LINCOLN Lincoln, NE Sameh S. Badie GEORGE WASHINGTON UNIVERSITY Washington, DC Christopher Y. Tuan UNIVERSITY OF NEBRASKA-LINCOLN Lincoln, NE 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 654 Project 18-14 ISSN 0077-5614 ISBN 978-0-309-11835-4 Library of Congress Control Number 2010926177 Â© 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 654 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 Danna Powell, Senior Program Assistant Eileen P. Delaney, Director of Publications Hilary Freer, Senior Editor NCHRP PROJECT 18-14 PANEL Field of Materials and ConstructionâArea of Concrete Materials Edward P. Wasserman, Tennessee DOT, Nashville, TN (Chair) Andre V. Pavlov, Florida DOT, Tallahassee, FL William E. Cook, Nebraska Concrete Paving Association, Lincoln, NE Paul Finnerty, Maryland State Highway Administration, Hanover, MD Z. John Ma, University of Tennessee, Knoxville, TN Michael R. Pope, California DOT, Sacramento, CA Chuck Prussack, Central Pre-Mix Prestress Company, Spokane, WA Richard B. Stoddard, Washington State DOT, Tumwater, WA Joey Hartmann, FHWA Liaison Stephen F. Maher, TRB Liaison 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 establishes a userâs manual for the acceptance, repair, or rejection of precast/ prestressed concrete girders with longitudinal web cracking. The report also proposes revi- sions to the AASHTO LRFD Bridge Design Specifications and provides recommendations to develop improved crack control reinforcement details for use in new girders. The material in this report will be of immediate interest to bridge engineers. Precast/prestressed concrete girders are widely used in the United States for bridge con- struction. Longitudinal web cracks have been observed during prestress transfer, particu- larly at the ends of girders. With the use of higher strength concrete, deeper girders, and sig- nificantly higher prestress forces, these cracks are becoming more prevalent and, in some cases, larger. Reactions to these cracks have ranged from doing nothing to rejecting girders. Other reactions include debonding strands at the ends, reducing permissible prestress force, reducing allowable compression stress at the time of transfer, injecting sealants into cracks, and coating the ends of girders with sealants. Clearly, there is no consensus on the causes of longitudinal cracking and what level of longitudinal cracking is unacceptable. A thorough understanding of whether longitudinal web cracks are of structural signifi- cance is needed. If these cracks are not structurally significant, an understanding of whether they reduce durability is required. Although published guidance exists regarding acceptance and repair criteria, these documents need validation. The research was performed under NCHRP Project 18-14 by the University of Nebraska â Lincoln with the assistance of the George Washington University, Washington, DC. The project established procedures for the acceptance, repair, or rejection of precast/prestressed concrete girders with longitudinal web cracking. A userâs manual for the application of these procedures was prepared. The report also provides recommendations for improved crack control reinforcement details for use in new girders, and proposes revisions to Article 5.10.10 of the AASHTO LRFD Bridge Design Specifications as warranted. Appendices A through G from the research agencyâs final report are not published herein but are available on the TRB website. These appendixes are titled as follows. â¢ Appendix AâLiterature Review â¢ Appendix BâNational Survey â¢ Appendix CâStructural Investigation & Full-Scale Girder Testing â¢ Appendix DâSealant Specifications â¢ Appendix EâASTM Specifications â¢ Appendix FâField Inspection of Bridges â¢ Appendix GâDesign Examples of End Zone Reinforcement F O R E W O R D By Waseem Dekelbab Staff Officer Transportation Research Board
AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 18-14 by the Department of Civil Engineering, University of Nebraska â Lincoln, Nebraska, and the Civil and Environmental Engineering Department, George Washington University, Washington, D.C. The work undertaken at George Wash- ington University was under individual subcontract with the University of Nebraska â Lincoln. Maher K. Tadros, the Leslie D. Martin Professor of Civil Engineering, Department of Civil Engineer- ing, University of Nebraska â Lincoln, was the principal investigator and an author of this report. Sameh S. Badie, Associate Professor of Civil Engineering, Civil and Environmental Engineering Department, George Washington University, was a co-principal investigator and an author of this report. Christopher Y. Tuan, Professor of Civil Engineering, Department of Civil Engineering, University of Nebraska â Lincoln, was a co-principal investigator. The authors would like to express their gratitude to Mark Lafferty, Vice President/General Manager, Concrete Industries Inc., Lincoln, Nebraska, and Steve Seguirant, Vice President and Director of Engi- neering, Concrete Technology Corporation (CTC), Tacoma, Washington, who served as consultants on this project, not only for their technical contributions during the various phases of the project, but also for their generous donations of the girders used for testing. The authors also wish to thank Todd Culp of Coreslabs, Inc., Omaha, Nebraska, for his timely coordination in the storage and transportation of the donated girders shipped to Omaha for testing. Also, the authors would like to thank Chad Saunders and Joe Rose of Bayshore Concrete Products Corporation, Cape Charles, Virginia; Don Thomson of Construc- tion Products, Inc., Jackson, Tennessee; and Standard Concrete Products, Inc., Tampa, Florida, for their generous donations of the girders used for testing. The authors would like to thank Mark Traynowicz, State Bridge Engineer; the engineers and personnel of the Bridge Division of the Nebraska Department of Roads (NDOR); Julius F.J. Volgyi, Assistant State Structure and Bridge Engineer; William F. Via, Material Engineer; Christopher R. Williams, Structures and Bridge Safety Inspection Engineer; and the engineers and personnel of the Structure and Bridge Divi- sion of the Virginia Department of Transportation (VDOT) for their help and support, which allowed the authors to inspect many concrete bridges in Nebraska and Virginia. The following individuals provided assistance during various phases of the project: Gary L. Krause, Associate Professor; Kromel Hanna, Assistant Research Professor; Christie J. Hasenkamp, research grad- uate student; and Kelvin J. Lein, Senior Laboratory Technician at the University of Nebraska â Lincoln, as well as Amir Arab, George Washington University PhD candidate. Their assistance and contributions are greatly appreciated and acknowledged.
C O N T E N T S 1 Summary 4 Chapter 1 Background 4 1.1 Problem Statement 4 1.2 Control of Cracking in Concrete Structures 4 1.2.1 Evolution of Permissible Crack Widths 7 1.2.2 Sources of End Zone Cracking 9 1.2.3 Design of End Zone Reinforcement 10 1.3 Methods and Materials Used for Repair 10 1.3.1 Epoxy Injection Procedure by PCI Manual for the Evaluation and Repair of Precast, Prestressed Concrete Bridge Products 11 1.3.2 Batching Materials and Sealants 11 1.4 Objective and Scope of the Research 11 1.5 Applicability of Results to Highway Practice 12 1.6 Organization of the Report 13 Chapter 2 Research Approach 15 Chapter 3 Research Findings 15 3.1 National Survey 16 3.2 Structural Investigation and Full-Scale Girder Testing 16 3.2.1 Introduction 17 3.2.2 Description of the Test Specimens and Test Setup 21 3.2.3 Test Setup 22 3.2.4 Test Results 30 3.2.5 Full-Scale Testing Conclusions 32 3.3 Epoxy Injection Testing 32 3.3.1 Introduction 32 3.3.2 Description of the Test Specimens 35 3.3.3 Preparation of the Test Specimens 36 3.3.4 Test Results 38 3.3.5 Discussion and Conclusions 40 3.4 Durability Testing 40 3.4.1 Introduction 40 3.4.2 Durability Test, Stage I 42 3.4.3 Durability Test, Stage II 47 3.4.4 Durability Test, Stage III 49 3.4.5 Chemical Composition of the Sealers 49 3.5 Field Inspections of Bridges 49 3.5.1 Introduction 50 3.5.2 Nebraska Department of Roads (NDOR) 53 3.5.3 Virginia Department of Transportation (VDOT) 58 3.5.4 Bridge Field Inspection Conclusions
58 3.6 Manual of Acceptance, Repair, or Rejection 59 3.7 Improved Crack Control Reinforcement Details for Use in New Girders 61 3.8 Proposed Revisions to the AASHTO LRFD Bridge Design Specifications 62 Chapter 4 Conclusions, Recommendations, and Suggested Future Research 62 4.1 Conclusions 62 4.2 Implementation of Research Findings in Highway Communities 63 4.3 Suggestions for Future Research 64 References 65 Appendices