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2020 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 951 Proposed AASHTO Load Rating Provisions for Implements of Husbandry Gongkang Fu E&T ConsulTing EnginEErs Tinley Park, IL Qing Wang Jingya Chi illinois insTiTuTE of TEChnology Chicago, IL Myint Lwin Olympia, WA Ross Corotis Boulder, CO Subscriber Categories Bridges and Other Structures 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 techniquesâthe 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 TRBâs 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; TRBâs 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&Iâs 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.nationalacademies.org and then searching for TRB Printed in the United States of America NCHRP RESEARCH REPORT 951 Project 12-110 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-67352-5 Library of Congress Control Number 2020947137 Â© 2020 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 manufacturersâ names 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 Boardâs 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 team would like to express its sincere gratitude for the project panelâs guidance, advice, and assistance throughout the course of study. The efforts of Mr. Scott Neubauer to make the unpublished measurement data set of the pooled fund study available to this project are particularly appreciated. The research team also thanks Mr. Matthew Chynoweth of the Michigan Department of Transportation (DOT) and Dr. Sreenivas Alampalli of New York State DOT, as well as their staff members, for their review of Interim Report No. 2. Mr. Leutrim Demiri, Mr. Abbass Divani, and Ms. Vivian Z. Cui performed some of the analyses and/or contributed to the artwork presented herein. State DOT personnel patiently answered questions and kindly provided information on various aspects of their practice and their weigh-in-motion (WIM) sites, which was critical to the success of this project. The research team grate- fully acknowledges the following individuals for providing the WIM data used in the calibration of live load factors for implements of husbandry: Dr. Ian Vaagenes of Minnesota DOT; Mses. Eileen Pankratz and Brittany N. Crawford and Messrs. Dan Bisom, Duane Williams, and Dave Gardner of Montana DOT; and Messrs. Richard Jones and Thad Tibbles of Ohio DOT. CRP STAFF FOR NCHRP RESEARCH REPORT 951 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Waseem Dekelbab, Senior Program Officer Tyler Smith, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications NCHRP PROJECT 12-110 PANEL Field of DesignâArea of Bridges Fouad A.H. Jaber, Nebraska DOT, Lincoln, NE (Chair) William Oliva, Wisconsin DOT, Madison, WI Kammy K. Bhala, California DOT, Sacramento, CA (retired) Rick Brice, Washington State DOT, Tumwater, WA Moises Dimaculangan, Minnesota DOT, Oakdale, MN Scott Neubauer, Iowa DOT, Ames, IA Francesco M. Russo, Michael Baker International, Philadelphia, PA Lubin Gao, FHWA Liaison Stephen F. Maher, TRB Liaison
This report presents bridge load rating procedures for implements of husbandry (IoH). The procedures are presented as a proposed AASHTO manual, a set of protocols, and examples of bridge load ratings for IoH. Comprehensive weigh-in-motion data collection and analysis were performed to develop the recommended live load factors. Various bridge spans and vehicle configurations were analyzed in order to develop the new live load dis- tribution factors. This report will be of immediate interest to bridge engineers responsible for bridge rating and ensuring public safety while allowing IoH to safely cross bridges. The size, geometry, and weight of farm equipment known as implements of husbandry (IoH) have increased and changed significantly to meet the needs of the modern agricultural industry. While intended primarily for use on the farm or in the field, IoH frequently travel on roads and bridges. A review of the history of bridge design vehicles and the evolution of truck size and weight legislation clearly shows that the growth of IoH has exceeded legal vehicles. Bridges are designed based on AASHTO live loads that are different from IoH. Therefore, research was needed to provide guidance to help bridge owners and engineers load rate bridges for IoH in order to both ensure public safety and preserve bridges. Research was performed under NCHRP Project 12-110 by E&T Consulting Engineers to (1) propose new IoH load rating provisions for the AASHTO Manual for Bridge Evaluation (load factor rating âLFRâ and load and resistance factor rating âLRFRâ) and related revisions to the AASHTO LRFD Bridge Design Specifications and (2) develop a set of protocols to evaluate IoH with various configurations for load rating and overload permits. F O R E W O R D By Waseem Dekelbab Staff Officer Transportation Research Board
1 Chapter 1 Background and Report Organization 3 Chapter 2 Research Approach 3 2.1 Phase IâPlanning 3 2.2 Phase IIâAnalytical Program 4 2.3 Phase IIIâProposed Provisions to the AASHTO Specifications 4 2.4 Phase IVâFinal Products 5 Chapter 3 Findings and Applications 5 3.1 Bridge Owner Survey and the State of the Practice 5 3.1.1 Survey 7 3.1.2 State Experience in Controlling IoH and the Impact on Bridge Safety 8 3.2 Literature Review and Relevant Subjects 9 3.2.1 IoH Vehicles and Their Model for Bridge Load Rating 9 3.2.2 Pooled Fund Study Sponsored by DOTs and USDA 14 3.2.3 Load Volume and Frequency 14 3.2.4 Transverse Distribution of the Two and Three Wheel Lines 15 3.2.5 Dynamic Impact Effect of IoH Vehicles 25 3.2.6 Presence of Multiple Vehicles on the Same Span 26 3.2.7 Code Calibration for IoH Load Rating 30 3.3 Objectives and Protocols of Load Rating for IoH Vehicles 31 3.4 Notional Load Models for IoH Vehicles 38 3.5 Live Load Lateral Distribution 38 3.5.1 Finite Element Modeling for Live Load Distribution 45 3.5.2 Scope of Bridge Types and Spans 46 3.5.3 Effects of Nonstandard Gauge Width 64 3.5.4 Effects of Tracked Wheels 65 3.5.5 Effects of Dual-Tire Wheels 67 3.5.6 Effects of Single-Tire Steering Axle 73 3.6 Dynamic Load Allowance IM and I for IoH Load Rating 74 3.6.1 Fourier Filtration for Extracting IM Factor and Impact Factor I 84 3.6.2 Load Test Data 85 3.6.3 IM Factor for LRFR and I for LFR Based on Load Test Results 88 3.7 Calibration for Live Load Factor for IoH Load Rating 88 3.7.1 WIM Data for Calibration 91 3.7.2 Calibration Approach 93 3.7.3 Temporal Projection for Future Maximum Load Effects 94 3.7.4 Calibration Results for IoH Load Rating 100 3.8 Proposed Revisions to Current AASHTO Specifications 101 Chapter 4 Conclusions and Suggested Research 102 Bibliography C O N T E N T S
107 Appendix A Protocols for Load Rating Bridges for Implements of Husbandry 137 Appendix B Proposed AASHTO Guide Manual for Bridge Evaluation for Implements of Husbandry 138 Appendix C Implementation of Research Findings and Products 139 Appendix D Questionnaires Used in Survey 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.