Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections (2023)

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2023 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 RESEARCH REPORT 1045 Improved Cross-Frame Analysis and Design WIDE-FLANGE T-SHAPE SECTIONS Sunghyun Park Matthew Reichenbach Todd Helwig Michael Engelhardt Ferguson Structural Engineering Laboratory The University of Texas at Austin Austin, TX Robert Connor Purdue University West Lafayette, IN Michael Grubb M.A. Grubb & Associates, LLC Wexford, PA Subscriber Categories Bridges and Other Structures • Construction • Design Research sponsored by the American Association of State Highway and Transportation Ofcials in cooperation with the Federal Highway Administration

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transporta- tion results in increasingly complex problems of wide interest to high- way authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniques—the National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration (FHWA), United States Department of Transportation, under Agree- ment No. 693JJ31950003. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRB’s recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRB’s relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs iden- tified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the FHWA. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&I’s recommendations are proposed to the AASHTO Board of Direc- tors and the National Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving 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 research 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 by going to https://www.mytrb.org/MyTRB/Store/default.aspx Printed in the United States of America NCHRP RESEARCH REPORT 1045 Project 12-113 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-69868-9 Library of Congress Control Number 2023937738 © 2023 by the National Academy of Sciences. National Academies of Sciences, Engineering, and Medicine and the graphical logo are trade- marks of the 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, APTA, FAA, FHWA, FTA, GHSA, or NHTSA 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 research report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the National Academies of Sciences, Engineering, and Medicine. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; the FHWA; or the program sponsors. The Transportation Research Board does not develop, issue, or publish standards or spec- ifications. The Transportation Research Board manages applied research projects which provide the scientific foundation that may be used by Transportation Research Board sponsors, industry associations, or other organizations as the basis for revised practices, procedures, or specifications. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names or logos appear herein solely because they are considered essential to the object of the report.

e National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. e National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. e National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. e three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. e National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. e Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. e mission of the Transportation Research Board is to provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. e Board’s varied activities annually engage about 8,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. e program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.

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 CRP STAFF FOR NCHRP RESEARCH REPORT 1045 Christopher J. Hedges, Director, Cooperative Research Programs Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program Ahmad Abu-Hawash, Senior Program Officer Sheila Moore, Program Associate Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Sreyashi Roy, Editor NCHRP PROJECT 12-113 PANEL Field of Design—Area of Bridges Norman L. McDonald, Ames, IA (Chair) Xiaohua Hannah Cheng, New Jersey Department of Transportation, Trenton, NJ Domenic A. Coletti, HDR, Raleigh, NC Karl H. Frank, Austin, TX John S. Hastings, National Steel Bridge Alliance (NSBA), Thompsons Station, TN Thomas P. Macioce, Carlisle, PA Michelle Lauren Romage-Chambers, Burgess & Niple, Austin, TX Dayi Wang, FHWA Liaison Stephen F. Maher, TRB Liaison

NCHRP Research Report 1045 presents improved bridge design requirements for the analysis and design of cross-frames using wide-flange T-shape (WT) sections in straight and curved steel I-girder bridges. The proposed requirements are based on comprehensive analytical and testing programs for investigating the effects of support skew on cross-frame behavior, fatigue design forces, strength and stiffness requirements for stability bracing, and the influence of cross-frame member end connections upon cross-frame stiffness. This report will be of immediate interest to bridge engineers. Recent developments in bridge design and analysis have created opportunities for improve- ments to cross-frame analysis and design for steel I-girder bridges. Improvements to cross- frame analysis and design were proposed in Stage 1 of the research conducted under NCHRP Project 12-113, as documented in NCHRP Research Report 962: Proposed Modification to AASHTO Cross-Frame Analysis and Design. However, the work in Stage 1 was limited to cross- frames constructed with single-angle sections. Additional research was needed to study other types of cross-frames that were commonly used by many states. The inclusion of addi- tional types of cross-frames, such as cross-frames constructed with wide-flange T-shape (WT) sections, will increase the applicability of the research findings from Stage 1 and could result in a dramatic improvement in the reliability and economy of cross-frames for steel I-girder bridges. Research was performed under Stage 2 of NCHRP Project 12-113 by the University of Texas at Austin and included (1) controlled live load tests and measurement of in-service stress cycle counts for three steel I-girder bridges and (2) an extensive analytical parametric study. The results of the live load tests and analytical study were used to develop the proposed requirements. F O R E W O R D By Ahmad Abu-Hawash Staff Officer Transportation Research Board

1 Chapter 1 Introduction 1 1.1 Background 4 1.2 Research Objectives 4 1.3 Organization of the Report 5 Chapter 2 Research Approach 6 2.1 Experimental Program and Model Validation 7 2.2 Parametric Finite Element Analytical Studies 9 Chapter 3 Experimental Program 9 3.1 Review of Typical WT Cross-Frame Details 13 3.2 Design and Detailing of Specimens 18 3.3 Experimental Testing Protocol 23 3.4 Experimental Results 31 3.5 Model Validation 39 Chapter 4 Parametric Studies 39 4.1 Stiffness Modification Factor 41 4.2 Panel-Level Parametric Study 52 4.3 System-Level Parametric Study 58 Chapter 5 Conclusions and Recommendations 58 5.1 Conclusions 59 5.2 Recommendations for Cross-Frame Analysis 61 References A-1 Appendix Design Drawings for Test Specimens C O N T E N T S