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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process. Washington, DC: The National Academies Press. doi: 10.17226/26223.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process. Washington, DC: The National Academies Press. doi: 10.17226/26223.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process. Washington, DC: The National Academies Press. doi: 10.17226/26223.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process. Washington, DC: The National Academies Press. doi: 10.17226/26223.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process. Washington, DC: The National Academies Press. doi: 10.17226/26223.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process. Washington, DC: The National Academies Press. doi: 10.17226/26223.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process. Washington, DC: The National Academies Press. doi: 10.17226/26223.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process. Washington, DC: The National Academies Press. doi: 10.17226/26223.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

2021 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 965 Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process Caroline Bennett Jian Li The University of Kansas Lawrence, KS Adolfo Matamoros The University of Texas San Antonio, TX Subscriber Categories Bridges and Other Structures • Construction • Materials 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, 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 965 Project 10-94 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-67400-3 Library of Congress Control Number 2021937565 © 2021 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, FTA, GHSA, NHTSA, or TDC 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; 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.

The 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. The 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. The 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. The 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. The 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. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The 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. The 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. The 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 AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 10-94 by the Department of Civil, Environmental, and Architectural Engineering at the University of Kansas (KU). Dr. Jian Li of KU was the principal investigator. The other authors are Dr. Caroline Bennett and Dr. Stan Rolfe, both of KU, and Dr. Adolfo Matamoros of The University of Texas at San Antonio (formerly with KU). Dr. John Barsom from John Barsom Consulting, Ltd.; Dr. Duane Miller from The Lincoln Electric Company; and Mr. Thomas J. Kinstler from GalvaScience, LLC, served as technical consultants for the project. Dr. Tom Schlafly from the American Institute of Steel Construction served as the technical advisor for this study. Their comments and valuable input are greatly appreciated. The research team also gratefully acknowledges technical input from Dr. Arturo Montoya of The University of Texas at San Antonio. Graduate students Dr. Kien Nguyen and Mr. Luke Bridwell, both of KU, and Dr. Reza Nasouri of The University of Texas at San Antonio made significant contributions to this research. CRP STAFF FOR NCHRP RESEARCH REPORT 965 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Amir N. Hanna, Senior Program Officer Emily Griswold, Program Coordinator Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications Lisa Whittington, Editor NCHRP PROJECT 10-94 PANEL Field of Materials and Construction—Area of Specifications, Procedures, and Practices Mary A. Grieco, Massachusetts Department of Transportation, Boston (Chair) Ernesto Flores, Pennsylvania Department of Transportation, Harrisburg Tom J. Langill, American Galvanizers Association, Centennial, CO Paul V. Liles, formerly with Georgia Department of Transportation, Atlanta Norman L. McDonald, formerly with Iowa Department of Transportation, Ames Gregory R. Perfetti, North Carolina Department of Transportation, Raleigh Justin M. Ocel, FHWA Liaison Nelson H. Gibson, TRB Liaison

NCHRP Research Report 965: Mitigation of Weldment Cracking in Steel Highway Struc- tures Due to the Galvanizing Process proposes modifications to the current AASHTO LRFD Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals and the AASHTO LRFD Bridge Design Specifications that, if implemented, will help mitigate weldment cracking that occurs due to the galvanizing process. This should enable these assets to achieve their intended service life and eliminate related safety concerns. This report will be of immediate interest to state bridge and construction engineers and others involved in the different aspects of steel structures. Structural supports for signs, luminaires, and traffic signals and other highway steel structures are generally galvanized to prevent corrosion and provide a long service life. However, recent investigations have revealed incidents of cracking in weldments of gal- vanized structures that appear related to the galvanizing process. When placed in service, structures with such flaws will exhibit short service lives and pose safety concerns. There was a need to identify the factors contributing to cracking of weldment in galvanized steel highway structures and to propose changes to current design, materials, and construction specifications to help mitigate such cracking. Implementing these changes will ensure that galvanized highway structures provide the intended service life and eliminate related safety concerns. Under NCHRP Project 10-94, “Mitigation of Weldment Cracking of Highway Steel Structures due to the Galvanizing Process,” the University of Kansas was charged with proposing improved design, materials, and construction specifications of galvanized steel highway structures—specifically structural supports for signs, luminaires, traffic signals, and bridge superstructures—to mitigate weldment cracking caused by the galvanizing process. To accomplish this objective, the researchers reviewed relevant literature and identified those factors contributing to cracking of weldments in galvanized steel struc- tures. They also conducted an experimental investigation and a computational study to evaluate the effect of these factors and their interactions on weldment cracking. Based on the findings of these investigations, the research team proposed changes to the AASHTO LRFD Specifications for Structural Supports to Highway Signs, Luminaires, and Traffic Signals, first edition, and the AASHTO LRFD Bridge Design Specifications, eighth edition. This report summarizes the work performed in the project and includes four appendices that provide further details on the different aspects of the research. The appendices are available online at www.trb.org by searching for NCHRP Research Report 965. F O R E W O R D By Amir N. Hanna Staff Officer Transportation Research Board

Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org) retains the color versions. 1 Summary 4 Chapter 1 Introduction and Research Scope 4 Problem Statement 4 Research Objective and Scope 4 Report Organization 6 Chapter 2 Background and Literature Review 7 LMAC Mechanism 10 Chapter 3 Factors Contributing to Weldment Cracking Due to the Galvanizing Process 10 Organization of Factors Contributing to Liquid Metal Assisted Cracking 10 Type 1 Cracking 13 Type 2 Cracking 13 Development of Test Plan 14 Research Approach 16 Chapter 4 Experimental Test Program 16 Tension Specimen Preparation 26 Tension Test Setup and Testing Protocols 30 Tension Testing Results 46 WOL Specimens 54 Chapter 5 Computational Simulations—High Mast Illumination Poles 54 Description of Parametric Study 58 Model Calibration 58 Results 65 Chapter 6 Summary and Recommendations for Research 65 Summary of Research Findings 68 Suggested Revisions to Current Specifications 68 Recommendations for Future Research 70 References 74 Attachment Proposed Specification Changes 75 Suggested Revisions to the AASHTO LRFD Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals, First Edition (2015) 81 Suggested Revisions to the AASHTO LRFD Bridge Design Specifications, Eighth Edition (2017) 85 Appendices C O N T E N T S

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Structural supports for signs, luminaires, and traffic signals and other steel highway structures are generally galvanized to prevent corrosion and provide a long service life. However, recent investigations have revealed incidents of cracking in weldments of galvanized structures that appear to be induced during the galvanizing process.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 965: Mitigation of Weldment Cracking in Steel Highway Structures Due to the Galvanizing Process proposes improved design, materials, and construction specifications of galvanized steel highway structures to mitigate weldment cracking caused by the galvanizing process.

Supplemental materials to the report are appendices that provide details of the work performed in the project.

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