Design of Roadside Barrier Systems Placed on MSE Retaining Walls (2010)

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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 663 Subscriber Categories Bridges and Other Structures Design of Roadside Barrier Systems Placed on MSE Retaining Walls Roger P. Bligh Jean-Louis Briaud Kang Mi Kim Akram Abu-Odeh TEXAS TRANSPORTATION INSTITUTE TEXAS A&M UNIVERSITY SYSTEM College Station, TX 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 Board’s recognized objectivity and understanding of modern research practices. 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The 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 Governing Board of the National Research Council. 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 Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of the report.

CRP STAFF FOR NCHRP REPORT 663 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Charles W. Niessner, Senior Program Officer Emily R. Greenwood, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Editor NCHRP PROJECT 22-20 PANEL Field of Design—Area of Vehicle Barrier Systems Mark P. McClelland, Texas DOT, Austin, TX (Chair) Alexander K. Bardow, Massachusetts DOT, Boston, MA Robert L. Chen, Parsons Brinckerhoff, Irvine, CA Ronald K. Faller, University of Nebraska–Lincoln, Lincoln, NE Grant Gummow, Utah DOT, Salt Lake City, UT Ramesh C. Gupta, Virginia DOT, Richmond, VA Christopher Hahin, Illinois DOT, Springfield, IL Michael L. McMullen, Denver, CO Silas Nichols, 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 presents a design procedure for roadside barrier systems mounted on the edge of a mechanically stabilized earth (MSE) wall. The procedures were developed following AASHTO Load Resistant Factor Design (LRFD) practices. The report will be of particular interest to personnel responsible for the structural design of MSE walls. It is estimated that 10 million square feet of mechanically stabilized earth (MSE) retain- ing wall is constructed annually in the United States. Most MSE retaining walls used in high- way fill applications are constructed with a roadside barrier system consisting of a traffic barrier placed on a structural footing (moment slab). The footing is intended to provide sta- bility for the barrier to resist impact loads and to reduce the influence of those impact loads on the retaining wall system by distributing the load over a wide area. The proper design of the roadside barrier, the structural slab, and the MSE wall system requires a good under- standing of how barrier impact loads are transferred through the structural slab and into the wall system. The move from the AASHTO Standard Specifications for Highway Bridges (ASD) to the AASHTO LRFD Bridge Design Specifications has made evident the need for a rational, reli- able procedure for designing roadside barrier systems placed on MSE retaining walls. Cur- rent procedures and design details for roadside barriers placed on retaining walls vary widely among state highway agencies. Most designs currently used are overly conservative because of inadequate understanding of how barrier impact loads are distributed through the bar- rier and transferred to the structural slab and the wall system. There is a need to develop procedures for use by state highway agencies in designing roadside barrier systems placed on MSE retaining walls. Under NCHRP Project 22-20, “Design of Roadside Barrier Systems Placed on MSE Retaining Walls,” Texas A&M Research Foundation reviewed the current design practice for roadside barriers, conducted a survey of state transportation agencies, performed finite element simulations, conducted static and dynamic tests using a bogie vehicle and a full- scale Test Level 3 crash test following the AASHTO Manual for Assessing Safety Hardware (MASH). Based on these evaluations, recommended design procedures were developed fol- lowing AASHTO LRFD design practices. The design procedures for the barrier system address sliding, overturning, and structural adequacy of the coping and wall panel. The reinforcement design procedure considers pull- out and rupture of the reinforcement. The dynamic design loads are specified using both a pressure distribution approach and a line load approach. F O R E W O R D By Charles W. Niessner Staff Officer Transportation Research Board

C O N T E N T S 1 Chapter 1 Introduction 1 1.1 Research Problem Statement 1 1.2 Research Objective 1 1.3 Research Approach 2 1.4 Report Scope 3 Chapter 2 State of the Practice 3 2.1 Design of MSE Wall 3 2.1.1 External Stability 3 2.1.2 Internal Stability 4 2.2 Design of Barrier 4 2.2.1 Background of Barrier Crash Testing Guidelines 7 2.2.2 Background of Barrier Design Loads 10 2.2.3 Barrier Design Practice 11 2.3 Design of the Barrier on Top of the MSE Wall 12 2.3.1 Design of MSE Wall for Barrier Impact 13 2.3.2 Comparison between ASD and LRFD 13 2.3.3 Previous Crash Test of Barrier on Edge of MSE Wall 15 2.4 Survey of State Transportation Agencies 15 2.4.1 MSE Walls 16 2.4.2 Barriers 17 2.4.3 Barrier Connection to Wall/Pavement 20 2.4.4 Design 21 2.4.5 Performance 22 Chapter 3 Barrier Stability Study 22 3.1 Description of Barrier 22 3.2 Static Analyses and Static Test 23 3.2.1 Static Analytical Solution 23 3.2.2 Quasi-static Finite Element Analysis 24 3.2.3 Full-Scale Static Test on Barrier 26 3.3 Dynamic Analyses and Dynamic Test 26 3.3.1 Full-Scale Dynamic Test (Bogie Test) on Barrier 32 3.3.2 Dynamic Analytical Simple Solution 34 3.3.3 Dynamic Finite Element Analysis 35 3.4 Conclusions 38 Chapter 4 Reinforcement Pullout Tests 38 4.1 Rate of Loading 38 4.2 Saturation 38 4.3 Fines 38 4.4 Reinforcement 41 4.5 Number of Tests

41 4.6 Procedure (Soil Installation, Rate of Loading, Testing) 41 4.7 Results and Conclusion 50 Chapter 5 5 ft High MSE Wall and Barrier Study 50 5.1 5 ft High MSE Wall and Barrier Test Plan 50 5.1.1 Calculation of MSE Wall Capacity 51 5.1.2 Calculation of Barrier Capacity 52 5.2 Finite Element Analysis 52 5.2.1 Modeling Methodology 57 5.2.2 Finite Element Model: Boundary Conditions 59 5.2.3 Simulated Impact into Barrier Placed on MSE Wall with 8 ft Long Strip 64 5.2.4 Simulated Impact into Barrier Placed on MSE Wall with 16 ft Long Strip 71 5.3 Bogie Test 71 5.3.1 5 ft High MSE Wall Construction and Test Installation 73 5.3.2 Bogie Test 1: New Jersey Barrier with 16 ft Strips 81 5.3.3 Bogie Test 2: Vertical Concrete Barrier with 8 ft Bar Mats 92 5.3.4 Bogie Test 3: Vertical Concrete Barrier with 8 ft Strips 105 5.3.5 Bogie Test 4: Vertical Concrete Barrier with 16 ft Strips 115 5.3.6 Damage of Moment Slab after Test 115 5.4 Summary of Bogie Tests 116 5.5 Comparison of Test and Numerical Simulation 123 Chapter 6 10 ft High MSE Wall and Barrier Study 123 6.1 10 ft High MSE Wall and Barrier Study Description 123 6.1.1 Calculation of MSE Wall Capacity 123 6.1.2 Calculation of Barrier Capacity 124 6.2 Finite Element Analysis 127 6.2.1 Barrier Damage and Displacement 128 6.2.2 Loads and Displacements in Reinforcement Strips 128 6.2.3 Panel Analysis 133 6.3 TL-3 Crash Test 133 6.3.1 10 ft High MSE Wall Construction and Test Installation 136 6.3.2 Impact Conditions 136 6.3.3 Test Vehicle 136 6.3.4 Test Description 138 6.3.5 Test Article and Vehicle Damage 139 6.3.6 Occupant Risk 139 6.3.7 Data from Accelerometers 143 6.3.8 Photographic Instrumentation 144 6.3.9 Load on the Strip from Strain Gages 146 6.3.10 Panel Analysis 146 6.3.11 Other Instrumentations 146 6.3.12 Damage of Moment Slab after Test 146 6.4 Conclusions 147 6.5 Comparison of Test and Simulation

152 Chapter 7 Design Guidelines 152 7.1 Guidelines for the Barrier 152 7.1.1 Sliding of the Barrier 152 7.1.2 Overturning of the Barrier 153 7.1.3 Rupture of the Coping in Bending 153 7.2 Guidelines for the Wall Reinforcement 153 7.2.1 Pullout of the Wall Reinforcement 155 7.2.2 Rupture of the Wall Reinforcement 156 7.3 Guidelines for the Wall Panel 156 7.4 Data to Back Up Guidelines 156 7.4.1 Barrier 159 7.4.2 Wall Reinforcement 163 Chapter 8 Summary and Conclusions 163 8.1 Summary of Studies and Tests 163 8.1.1 Study of Barrier Stability 163 8.1.2 Pullout Tests on the Reinforcement 163 8.1.3 Study of 5 ft MSE Wall and Barrier 164 8.1.4 Study of 10 ft MSE Wall and Barrier 164 8.2 Conclusions 166 References 168 Appendices A–H 169 Appendix I AASHTO LRFD Format Design Guideline 178 Appendix J Example of Design Guideline Note: Many of the photographs, figures, and tables in this report 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.