Development of LRFD Specifications for Horizontally Curved Steel Girder Bridges (2006)

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T R A N S P O R T A T I O N R E S E A R C H B O A R D WASHINGTON, D.C. 2006 www.TRB.org NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM NCHRP REPORT 563 Research Sponsored by the American Association of State Highway and Transportation Officials in Cooperation with the Federal Highway Administration SUBJECT AREAS Bridges, Other Structures, Hydraulics and Hydrology Development of LRFD Specifications for Horizontally Curved Steel Girder Bridges JOHN M. KULICKI WAGDY G. WASSEF DANIELLE D. KLEINHANS Modjeski and Masters, Inc. Harrisburg, PA CHAI H. YOO Auburn University Auburn, AL ANDRZEJ S. NOWAK University of Nebraska Lincoln, NE MIKE GRUBB Bridge Software Development International, Ltd. Coopersburg, PA

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COOPERATIVE RESEARCH PROGRAMS STAFF FOR NCHRP REPORT 563 ROBERT J. REILLY, Director, Cooperative Research Programs CRAWFORD F. JENCKS, Manager, NCHRP DAVID B. BEAL, Senior Program Officer EILEEN P. DELANEY, Director of Publications BETH HATCH, Editor NCHRP PROJECT 12-52 Field of Design—Area of Bridges EDWARD P. WASSERMAN, Tennessee DOT (Chair) RALPH E. ANDERSON, Illinois DOT KARL FRANK, University of Texas at Austin GREGG C. FREDRICK, Wyoming DOT THOMAS P. MACIOCE, Pennsylvania DOT VASANT C. MISTRY, FHWA MARK RENO, Quincy Engineering, Inc., Sacramento, CA KEVIN WESTERN, Minnesota DOT WILLIAM WRIGHT, FHWA SHEILA RIMAL DUWADI, FHWA Liaison STEPHEN F. MAHER, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Proj- ect 12-52. Modjeski and Masters, Inc., was the contractor. Dr. John M. Kulicki was the principal investigator. Other co-authors, acting as sub-consultants to Modjeski and Masters, and their main contri- bution to the work are as follows: • Dr. Chai H. Yoo, Auburn University: Literature search • Dr. Andrzej S. Nowak, University of Nebraska: Statistical calibration • Mr. Mike Grubb, Bridge Software Development International, Ltd.: Preparation of the specifications articles. The research team would like to acknowledge the contributions of many of Modjeski and Masters’s staff. Particularly acknowledged are the contributions of Mr. Christopher Smith and Mr. Kevin Johns to the preparation of two curved girders design examples, which are available online at http://www.transportation.org/sites/bridges/ docs/Box%20Girder.pdf and http://www.transportation.org/sites/ bridges/docs/I-Girder.pdf. The research team would like to acknowledge the support of the AASHTO Technical Committee on Steel Bridges, T14. The support and technical contributions of the committee’s chair, Mr. Ed Wasserman, Civil Engineering Director, Structures Division, Ten- nessee Department of Transportation, are gratefully acknowledged. Dr. Donald White, Georgia Institute of Technology, provided sig- nificant technical support in incorporating the results of his work on many other research projects into the recommended specifications. Dr. Dennis Mertz, University of Delaware, reviewed and com- mented on the recommended specification articles. His contribu- tions to the work are greatly appreciated.

This report contains the findings of research performed to develop design specifications for horizontally curved steel girder bridges. The developed specifications have been adopted by AASHTO and are included in the 2005 Interims to the third edition of the AASHTO LRFD Bridge Design Specifications. Detailed examples showing the application of the speci- fications to the design of an I-girder bridge and a box-girder bridge are available from AASHTO. The material in this report will be of immediate interest to bridge designers. In the late 1980s and early 1990s, AASHTO and the FHWA recognized the need to address problems with design and construction of horizontally curved steel girder highway bridges. AASHTO, through the NCHRP, embarked on an overhaul of the AASHTO Guide Specifications for Horizontally Curved Highway Bridges. NCHRP Project 12-38, “Improved Design Specifications for Horizontally Curved Steel Girder Highway Bridges,” provided rec- ommended load factor design (LFD) and construction specifications based on the state of the art that addressed many of the problems associated with the design and construction of these structures. While the LFD specifications were under development, the FHWA and others began conducting significant research that enhanced the understanding of steel bridge behavior in general and horizontally curved bridges in particular. The FHWA research included tests on a full-scale I-girder bridge, and knowledge of the moment and shear capacities of hor- izontally curved I-girder bridges resulted from this research. Analytical work, also funded by the FHWA, resulted in the unification of the design equations for straight and curved steel girders. NCHRP Project 12-52 was performed by Modjeski & Masters, Inc., with the assistance of Mike Grubb, Andrzej Nowak, Don White, and Chai Yoo. The report fully documents the effort leading to the specifications and contains an extensive compilation of abstracts of horizontally curved girder bridge research reports. Appendix C, “Calibration of LRFD Design Specifications for Steel Curved Girder Bridges,” and Appendix D, “Comparison of Curved Steel I-Girder Bridge Design Specifications,” can be downloaded from http://trb.org/ news/blurb_detail.asp?id=5965 or from the Project 12-52 website at trb.org/nchrp. F O R E W O R D By David B. Beal Staff Officer Transportation Research Board

C O N T E N T S 1 Summary 3 Chapter 1 Introduction and Research Approach 3 1.1 Introduction 4 1.2 Research Objective 4 1.3 Scope of the Study 4 1.4 Research Approach 6 Chapter 2 Findings 6 2.1 Literature Search 6 2.2 Design Specifications 6 2.3 Calibration 6 2.3.1 Scope 7 2.3.2 Study Bridges 7 2.3.3 Calibration Procedure 8 2.3.4 Load Models 8 2.3.4.1 Load Components 8 2.3.4.2 Dead Load 8 2.3.4.3 Live Load 9 2.3.4.4 Dynamic Load 10 2.3.4.5 Load Ratios 11 2.3.5 Resistance Models 11 2.3.6 Calibration Results 11 2.4 Design Comparisons 11 2.4.1 Objective 11 2.4.2 Application of the NCHRP 12-50 Process 13 2.4.3 Methodology 17 2.4.4 Shear Design 19 2.4.5 Flexural Design 20 2.4.6 Summary of Comparison Results 21 2.5 Design Examples 23 Chapter 3 Conclusions 24 References A-i Appendix A Literature Search B-i Appendixes B–D Related Materials