Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
Home
My WebLink
About
RR-40 - AASHTO LRFD Bridge Design Specifications - 9th Edition
LRFD BRIDGE DESIGN SPECIFICATIONS 9th Edition | 2020 978-1-56051-738-2 | LRFDBDS-9 RR-40 – CA received 8/22/25, Exhibit 40 © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 American Association of State Highway and Transportation Officials 555 12th Street, NW, Suite 1000 Washington, DC 20004 202-624-5800 phone/202-624-5806 fax www.transportation.org Cover photos: Top: Stan Musial Veterans Memorial Bridge at sunset, with the St. Louis, MO city skyline in the distance. Photo provided by Missouri Department of Transportation. Bottom: Segment K, Shreveport, LA. Segment K is a portion of the 36-mile I-49 Corridor which is a four- lane Interstate highway with a 4 ft inside shoulder and a 10 ft outside shoulder from the Arkansas state line to the Port of NOLA. Photo provided by PCL Civil Constructors, Inc. © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. ISBN: 978-1-56051-738-2 Pub Code: LRFDBDS-9 © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS 555 12th Street, NW, Suite 1000 Washington, DC 20004 EXECUTIVE COMMITTEE 2019–2020 OFFICERS: PRESIDENT: Patrick McKenna, Missouri* VICE PRESIDENT: Victoria Sheehan, New Hampshire* SECRETARY-TREASURER: Scott Bennett, Arkansas EXECUTIVE DIRECTOR: Jim Tymon, Washington, D. C. REGIONAL REPRESENTATIVES: REGION I: Vacant Diane Gutierrez-Scaccetti, New Jersey REGION II: Melinda McGrath, Mississippi Russell McMurry, Georgia REGION III: Mark Lowe, Iowa Craig Thompson, Wisconsin REGION IV: Kyle Schneweis, Nebraska James Bass, Texas IMMEDIATE PAST PRESIDENT: Carlos Braceras, Utah *Elected at the 2019 Annual Meeting in St. Louis, Missouri i © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 AASHTO COMMITTEE ON BRIDGES AND STRUCTURES, 2019 CARMEN E.L. SWANWICK, Chair SCOT BECKER, Vice Chair JOSEPH L. HARTMANN, Federal Highway Administration, U.S. DOT Liaison PATRICIA J. BUSH, AASHTO Liaison ALABAMA, William “Tim” Colquett, Eric J. Christie, Randall Mullins ALASKA, Richard A. Pratt, Leslie Daughtery, Elmer E. Marx ARIZONA, David L. Eberhart, David Benton, Pe-Shen Yang ARKANSAS, Charles “Rick” Ellis, Michael Hill, Joe Sartini CALIFORNIA, Thomas A. Ostrom, Gedmund Setberg, Dolores Valls COLORADO, Michael Collins, Stephen Harelson, Jessica Martinez CONNECTICUT, Timothy D. Fields, Mary E. Baker DELAWARE, Jason N. Hastings, Jason Arndt, Craig A. Stevens DISTRICT OF COLUMBIA, Konjit C. “Connie” Eskender, Donald L. Cooney, Richard Kenney FLORIDA, Sam Fallaha, William Potter, Jeff A. Pouliotte GEORGIA, Bill DuVall, Douglas D. Franks, Steve Gaston HAWAII, James Fu, Kevin Murata, John Williams IDAHO, Matthew M. Farrar ILLINOIS, Carl Puzey, Tim A. Armbrecht, Jayme Schiff INDIANA, Anne M. Rearick, Andrew Fitzgerald, Stephanie Wagner IOWA, James S. Nelson, Ahmad Abu-Hawash, Michael Nop KANSAS, Karen Peterson KENTUCKY, Bart Asher, Andy Barber, Marvin Wolfe LOUISIANA, Zhengzheng “Jenny” Fu, Artur D’Andrea, Chris Guidry MAINE, Wayne L. Frankhauser, Jeff S. Folsom, Michael H. Wight MARYLAND, Maurizio Agostino, Jesse Creel, Jeffrey Robert MASSACHUSETTS, Alexander K. Bardow, Joe Rigney MICHIGAN, Matthew Chynoweth, Rebecca Curtis, Richard E. Liptak MINNESOTA, Kevin L. Western, Arielle Ehrlich, Ed Lutgen MISSISSIPPI, Justin Walker, Scott Westerfield MISSOURI, Dennis Heckman, Greg E. Sanders MONTANA, Stephanie Brandenberger, Amanda Jackson, Dustin E. Rouse NEBRASKA, Mark J. Traynowicz, Mark Ahlman, Fouad Jaber NEVADA, Jessen Mortensen, Troy Martin NEW HAMPSHIRE, Robert Landry, David L. Scott NEW JERSEY, Eddy Germain, Xiaohua “Hannah” Cheng NEW MEXICO, Shane Kuhlman, Kathy Crowell, Jeff C. Vigil NEW YORK, Richard Marchione, Brenda Crudele, Ernest Holmberg NORTH CAROLINA, Brian Hanks, Scott Hidden, Girchuru Muchane NORTH DAKOTA, Jon D. Ketterling, Jason R. Thorenson OHIO, Timothy J. Keller, Alexander B.C. Dettloff, Jeffrey E. Syar OKLAHOMA, Steven J. Jacobi, Walter L. Peters, Tim Tegeler OREGON, Albert Nako, Tanarat Potisuk PENNSYLVANIA, Thomas P. Macioce, Richard Runyen, Louis J. Ruzzi PUERTO RICO, (Vacant) RHODE ISLAND, Georgette K. Chahine, Keith Gaulin SOUTH CAROLINA, Terry B. Koon, Hongfen Li, Jeff Sizemore SOUTH DAKOTA, Steve Johnson, Dave Madden, Todd S. Thompson TENNESSEE, Ted A. Kniazewycz iii © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 TEXAS, Graham Bettis, Bernie Carrasco, Jamie F. Farris UTAH, Carmen E.L. Swanwick, Cheryl Hersh Simmons, Rebecca Nix VERMONT, Kristin M. Higgins, Jim Lacroix VIRGINIA, Kendal R. Walus, Prasad L. Nallapaneni, Andrew M. Zickler WASHINGTON STATE, Mark A. Gaines, Tony M. Allen, Bijan Khaleghi WEST VIRGINIA, Tracy W. Brown, Ahmed Mongi WISCONSIN, Scot Becker, Bill C. Dreher, William L. Oliva WYOMING, Michael E. Menghini, Jeff R. Booher, Paul Cortez MARYLAND TRANSPORTATION AUTHORITY, James Harkness MULTNOMAH COUNTY TRANSPORTATION DIVISION, Jon Henrichsen NEW YORK STATE BRIDGE AUTHORITY, William Moreau TRANSPORTATION RESEARCH BOARD, Waseem Dekelbab U.S. ARMY CORPS OF ENGINEERS— Phillip W. Sauser U.S. COAST GUARD, Kamal Elnahal U.S. DEPARTMENT OF AGRICULTURE— FOREST SERVICE, John R. Kattell iv © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 FOREWORD The first broadly recognized national standard for the design and construction of bridges in the United States was published in 1931 by the American Association of State Highway Officials (AASHO), the predecessor to AASHTO. With the advent of the automobile and the establishment of highway departments in all of the American states dating back to just before the turn of the century, the design, construction, and maintenance of most U.S. bridges was the responsibility of these departments and, more specifically, the chief bridge engineer within each department. It was natural, therefore, that these engineers, acting collectively as the AASHTO Highway Subcommittee on Bridges and Structures (now the Committee on Bridges and Structures), would become the author and guardian of this first bridge standard. This first publication was entitled Standard Specifications for Highway Bridges and Incidental Structures. It quickly became the de facto national standard and, as such, was adopted and used by not only the state highway departments but also other bridge-owning authorities and agencies in the United States and abroad. Rather early on, the last three words of the original title were dropped and it has been reissued in consecutive editions at approximately four-year intervals ever since as Standard Specifications for Highway Bridges, with the final 17th edition appearing in 2002. The body of knowledge related to the design of highway bridges has grown enormously since 1931 and continues to do so. Theory and practice have evolved greatly, reflecting advances through research in understanding the properties of materials, in improved materials, in more rational and accurate analysis of structural behavior, in the advent of computers and rapidly advancing computer technology, in the study of external events representing particular hazards to bridges such as seismic events and stream scour, and in many other areas. The pace of advances in these areas has, if anything, stepped up in recent years. In 1986, the Subcommittee submitted a request to the AASHTO Standing Committee on Research to undertake an assessment of U.S. bridge design specifications, to review foreign design specifications and codes, to consider design philosophies alternative to those underlying the Standard Specifications, and to render recommendations based on these investigations. This work was accomplished under the National Cooperative Highway Research Program (NCHRP), an applied research program directed by the AASHTO Standing Committee on Research and administered on behalf of AASHTO by the Transportation Research Board (TRB). The work was completed in 1987, and, as might be expected with a standard incrementally adjusted over the years, the Standard Specifications were judged to include discernible gaps, inconsistencies, and even some conflicts. Beyond this, the specification did not reflect or incorporate the most recently developing design philosophy, load-and-resistance factor design (LRFD), a philosophy which has been gaining ground in other areas of structural engineering and in other parts of the world such as Canada and Europe. From its inception until the early 1970s, the sole design philosophy embedded within the Standard Specifications was one known as working stress design (WSD). WSD establishes allowable stresses as a fraction or percentage of a given material’s load-carrying capacity, and requires that calculated design stresses not exceed those allowable stresses. Beginning in the early 1970s, WSD began to be adjusted to reflect the variable predictability of certain load types, such as vehicular loads and wind forces, through adjusting design factors, a design philosophy referred to as load factor design (LFD). A further philosophical extension results from considering the variability in the properties of structural elements, in similar fashion to load variabilities. While considered to a limited extent in LFD, the design philosophy of load-and- resistance factor design (LRFD) takes variability in the behavior of structural elements into account in an explicit manner. LRFD relies on extensive use of statistical methods, but sets forth the results in a manner readily usable by bridge designers and analysts. Starting with the Eighth Edition of the AASHTO LRFD Bridge Design Specifications, interim changes to the Specifications were discontinued, and new editions are published on a three-year cycle. Changes are balloted and approved by at least two-thirds of the members of the Committee on Bridges and Structures. AASHTO members include the 50 State Highway or Transportation Departments, the District of Columbia, and Puerto Rico. Each member has one vote. The U.S. Department of Transportation is a non-voting member. Orders for Specifications may be placed by visiting the AASHTO Store, store.transportation.org; calling the AASHTO Publication Sales Office toll free (within the U.S. and Canada), 1-800-231-3475; or mailing to P.O. Box 933538, Atlanta, GA 31193-3538. A free copy of the current publication catalog can be downloaded from the AASHTO Store. v © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 vi For additional publications prepared and published by the Committee on Bridges and Structures and by other AASHTO Committees, please look online in the AASHTO Store (store.transportation.org) under “Bridges and Structures.” Suggestions for the improvement of the AASHTO LRFD Bridge Design Specifications are welcomed, just as they were for the Standard Specifications for Highway Bridges before them, at www.transportation.org. The following have served as chair of the Committee on Bridges and Structures since its inception in 1921: E. F. Kelley, who pioneered the work of the Committee; Albin L. Gemeny; R. B. McMinn; Raymond Archiband; G. S. Paxson; E. M. Johnson; Ward Goodman; Charles Matlock; Joseph S. Jones; Sidney Poleynard; Jack Freidenrich; Henry W. Derthick; Robert C. Cassano; Clellon Loveall; James E. Siebels; David Pope; Tom Lulay; Malcolm T. Kerley; Gregg Fredrick; and Carmen Swanwick. The Committee expresses its sincere appreciation of the work of these individuals and of those active members of the past, whose names, because of retirement, are no longer on the roll. The Committee would also like to thank John M. Kulicki, Ph.D., and his associates at Modjeski and Masters for their valuable assistance in the preparation of the AASHTO LRFD Bridge Design Specifications. © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 PREFACE AND ABBREVIATED TABLE OF CONTENTS The AASHTO LRFD Bridge Design Specifications, Ninth Edition contains the following 15 sections and an index: 1.Introduction 2.General Design and Location Features 3.Loads and Load Factors 4.Structural Analysis and Evaluation 5.Concrete Structures 6.Steel Structures 7.Aluminum Structures 8.Wood Structures 9.Decks and Deck Systems 10.Foundations 11.Abutments, Piers, and Walls 12.Buried Structures and Tunnel Liners 13.Railings 14.Joints and Bearings 15.Design of Sound Barriers Index Detailed Tables of Contents precede each section. The last article of each section is a list of references displayed alphabetically by author. Figures, tables, and equations are denoted by their home article number and an extension, for example 1.2.3.4.5-1 wherever they are cited. In early editions, when they were referenced in their home article or its commentary, these objects were identified only by the extension. For example, in Article 1.2.3.4.5, Eq. 1.2.3.4.5-2 would simply have been called “Eq. 2.” The same convention applies to figures and tables. Starting with this edition, these objects are identified by their whole nomenclature throughout the text, even within their home articles. This change was to increase the speed and accuracy of electronic production (i.e., CDs and downloadable files) with regard to linking citations to objects. Please note that the AASHTO materials standards (starting with M or T) cited throughout the LRFD Bridge Design Specifications can be found in Standard Specifications for Transportation Materials and Methods of Sampling and Testing, adopted by the AASHTO Highway Subcommittee on Materials. The individual standards are also available as downloads on the AASHTO Store, https://store.transportation.org. Unless otherwise indicated, these citations refer to the current edition. ASTM materials specifications are also cited and have been updated to reflect ASTM’s revised coding system, i.e., spaces removed between the letter and number. vii © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 SECTION 11: WALLS, ABUTMENTS, AND PIERS TABLE OF CONTENTS 11-i 11 11.1—SCOPE ............................................................................................................................................................. 11-1 11.2—DEFINITIONS ................................................................................................................................................. 11-1 11.3—NOTATION ..................................................................................................................................................... 11-2 11.3.1—General ................................................................................................................................................... 11-2 11.4—SOIL PROPERTIES AND MATERIALS ....................................................................................................... 11-7 11.4.1—General ................................................................................................................................................... 11-7 11.4.2—Determination of Soil Properties............................................................................................................ 11-7 11.5—LIMIT STATES AND RESISTANCE FACTORS ......................................................................................... 11-7 11.5.1—General ................................................................................................................................................... 11-7 11.5.2—Service Limit States ............................................................................................................................... 11-8 11.5.3—Strength Limit State ............................................................................................................................... 11-9 11.5.4—Extreme Event Limit State ..................................................................................................................... 11-9 11.5.4.1—General Requirements ................................................................................................................. 11-9 11.5.4.2—Extreme Event I, No Analysis ..................................................................................................... 11-9 11.5.5—Resistance Requirement ....................................................................................................................... 11-11 11.5.6—Load Combinations and Load Factors ................................................................................................. 11-11 11.5.7—Resistance Factors—Service and Strength ........................................................................................... 11-15 11.5.8—Resistance Factors—Extreme Event Limit State ................................................................................. 11-18 11.6—ABUTMENTS AND CONVENTIONAL RETAINING WALLS ................................................................ 11-19 11.6.1—General Considerations ........................................................................................................................ 11-19 11.6.1.1—General....................................................................................................................................... 11-19 11.6.1.2—Loading ...................................................................................................................................... 11-19 11.6.1.3—Integral Abutments .................................................................................................................... 11-20 11.6.1.4 —Wingwalls ................................................................................................................................. 11-20 11.6.1.5—Reinforcement ........................................................................................................................... 11-20 11.6.1.5.1—Conventional Walls and Abutments ................................................................................ 11-20 11.6.1.5.2—Wingwalls ........................................................................................................................ 11-20 11.6.1.6 —Expansion and Contraction Joints ............................................................................................. 11-21 11.6.2—Movement at the Service Limit State ................................................................................................... 11-21 11.6.2.1—Abutments .................................................................................................................................. 11-21 11.6.2.2—Conventional Retaining Walls ................................................................................................... 11-21 11.6.3—Bearing Resistance and Stability at the Strength Limit State ............................................................... 11-21 11.6.3.1—General....................................................................................................................................... 11-21 11.6.3.2—Bearing Resistance ..................................................................................................................... 11-21 11.6.3.3—Eccentricity Limits ..................................................................................................................... 11-24 11.6.3.4—Subsurface Erosion .................................................................................................................... 11-24 11.6.3.5—Passive Resistance ..................................................................................................................... 11-24 11.6.3.6—Sliding ........................................................................................................................................ 11-24 11.6.3.7—Overall Stability ......................................................................................................................... 11-24 11.6.4—Safety against Structural Failure .......................................................................................................... 11-25 11.6.5—Seismic Design for Abutments and Conventional Retaining Walls ..................................................... 11-25 11.6.5.1—General....................................................................................................................................... 11-25 11.6.5.2—Calculation of Seismic Acceleration Coefficients for Wall Design ........................................... 11-27 11.6.5.2.1—Characterization of Acceleration at Wall Base ................................................................ 11-27 11.6.5.2.2—Estimation of Acceleration Acting on Wall Mass ........................................................... 11-28 11.6.5.3—Calculation of Seismic Active Earth Pressures .......................................................................... 11-29 11.6.5.4—Calculation of Seismic Earth Pressure for Nonyielding Abutments and Walls ......................... 11-32 11.6.5.5—Calculation of Seismic Passive Earth Pressure .......................................................................... 11-32 11.6.5.6—Wall Details for Improved Seismic Performance ...................................................................... 11-34 11.6.6—Drainage ............................................................................................................................................... 11-35 11.7—PIERS............................................................................................................................................................. 11-35 11.7.1—Load Effects in Piers ............................................................................................................................ 11-35 11.7.2—Pier Protection...................................................................................................................................... 11-35 11.7.2.1—Collision ..................................................................................................................................... 11-35 11.7.2.2—Collision Walls .......................................................................................................................... 11-35 11.7.2.3—Scour .......................................................................................................................................... 11-36 © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 11-ii AASHTO LRFD BRIDGE DESIGN SPECIFICATIONS, NINTH EDITION, 2020 11.7.2.4—Facing ......................................................................................................................................... 11-36 11.8—NONGRAVITY CANTILEVERED WALLS ............................................................................................... 11-36 11.8.1—General ................................................................................................................................................. 11-36 11.8.2—Loading ................................................................................................................................................ 11-36 11.8.3—Movement at the Service Limit State ................................................................................................... 11-36 11.8.3.1—Movement .................................................................................................................................. 11-36 11.8.4—Safety against Soil Failure at the Strength Limit State ......................................................................... 11-36 11.8.4.1—Overall Stability ......................................................................................................................... 11-36 11.8.5—Safety against Structural Failure .......................................................................................................... 11-38 11.8.5.1—Vertical Wall Elements .............................................................................................................. 11-38 11.8.5.2—Facing ......................................................................................................................................... 11-38 11.8.6—Seismic Design of Nongravity Cantilever Walls .................................................................................. 11-39 11.8.6.1—General ....................................................................................................................................... 11-39 11.8.6.2—Seismic Active Lateral Earth Pressure ....................................................................................... 11-40 11.8.6.3—Seismic Passive Lateral Earth Pressure ...................................................................................... 11-41 11.8.6.4—Wall Displacement Analyses to Determine Earth Pressures ...................................................... 11-42 11.8.7—Corrosion Protection ............................................................................................................................ 11-44 11.8.8—Drainage ............................................................................................................................................... 11-44 11.9—ANCHORED WALLS ................................................................................................................................... 11-44 11.9.1—General ................................................................................................................................................. 11-44 11.9.2—Loading ................................................................................................................................................ 11-45 11.9.3—Movement at the Service Limit State ................................................................................................... 11-45 11.9.3.1—Movement .................................................................................................................................. 11-45 11.9.4—Safety against Soil Failure.................................................................................................................... 11-46 11.9.4.1—Bearing Resistance ..................................................................................................................... 11-46 11.9.4.2—Anchor Pullout Capacity ............................................................................................................ 11-47 11.9.4.3—Passive Resistance ..................................................................................................................... 11-50 11.9.4.4—Overall Stability ......................................................................................................................... 11-50 11.9.5—Safety Against Structural Failure ......................................................................................................... 11-50 11.9.5.1—Anchors ...................................................................................................................................... 11-50 11.9.5.2—Vertical Wall Elements .............................................................................................................. 11-52 11.9.5.3—Facing ......................................................................................................................................... 11-52 11.9.6—Seismic Design ..................................................................................................................................... 11-53 11.9.7—Corrosion Protection ............................................................................................................................ 11-54 11.9.8—Construction and Installation ............................................................................................................... 11-54 11.9.8.1—Anchor Stressing and Testing .................................................................................................... 11-54 11.9.9—Drainage ............................................................................................................................................... 11-55 11.10—MECHANICALLY STABILIZED EARTH WALLS ................................................................................. 11-55 11.10.1—General ............................................................................................................................................... 11-55 11.10.2—Structure Dimensions ......................................................................................................................... 11-57 11.10.2.1—Minimum Length of Soil Reinforcement ................................................................................. 11-58 11.10.2.2—Minimum Front Face Embedment ........................................................................................... 11-59 11.10.2.3—Facing ....................................................................................................................................... 11-60 11.10.2.3.1—Stiff or Rigid Concrete, Steel, and Timber Facings ....................................................... 11-60 11.10.2.3.2—Flexible Wall Facings .................................................................................................... 11-61 11.10.2.3.3—Corrosion Issues for MSE Facing .................................................................................. 11-61 11.10.3—Loading .............................................................................................................................................. 11-61 11.10.4—Movement at the Service Limit State ................................................................................................. 11-61 11.10.4.1—Settlement ................................................................................................................................ 11-61 11.10.4.2—Lateral Displacement ............................................................................................................... 11-62 11.10.4.3—Soil Failure (Internal Stability) ................................................................................................ 11-63 11.10.5—Safety against Soil Failure (External Stability) .................................................................................. 11-64 11.10.5.1—General ..................................................................................................................................... 11-64 11.10.5.2—Loading .................................................................................................................................... 11-64 11.10.5.3—Sliding ...................................................................................................................................... 11-65 11.10.5.4—Bearing Resistance ................................................................................................................... 11-66 11.10.5.5—Overturning .............................................................................................................................. 11-66 11.10.5.6—Overall and Compound Stability .............................................................................................. 11-66 11.10.6—Safety against Structural Failure (Internal Stability) .......................................................................... 11-68 © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 SECTION 11: WALLS, ABUTMENTS, AND PIERS 11-iii 11.10.6.1—General ..................................................................................................................................... 11-68 11.10.6.2—Loading (Internal Stability) ..................................................................................................... 11-68 11.10.6.2.1—Maximum Reinforcement Loads ................................................................................... 11-69 11.10.6.2.1a—Special Loading Conditions .................................................................................. 11-70 11.10.6.2.1b—Reinforcement Spacing for Calculation of Tmax .................................................... 11-72 11.10.6.2.1c—Calculation of Lateral Earth Pressure Coefficients for Determination of Tmax...... 11-73 11.10.6.2.1d—Coherent Gravity Method ..................................................................................... 11-74 11.10.6.2.1e—Stiffness Method ................................................................................................... 11-76 11.10.6.2.2—Reinforcement Loads at Connection to Wall Face ........................................................ 11-79 11.10.6.3—Reinforcement Pullout ............................................................................................................. 11-79 11.10.6.3.1—Boundary between Active and Resistant Zones ............................................................. 11-79 11.10.6.3.2—Reinforcement Pullout Design ....................................................................................... 11-81 11.10.6.4—Reinforcement Strength ........................................................................................................... 11-84 11.10.6.4.1—General .......................................................................................................................... 11-84 11.10.6.4.2—Design Life Considerations ........................................................................................... 11-88 11.10.6.4.2a—Steel Reinforcements ............................................................................................ 11-88 11.10.6.4.2b—Geosynthetic Reinforcements ............................................................................... 11-90 11.10.6.4.3—Design Tensile Resistance ............................................................................................. 11-93 11.10.6.4.3a—Steel Reinforcements ............................................................................................ 11-93 11.10.6.4.3b—Geosynthetic Reinforcements ............................................................................... 11-94 11.10.6.4.4—Reinforcement/Facing Connection Design Strength ...................................................... 11-94 11.10.6.4.4a—Steel Reinforcements ............................................................................................ 11-94 11.10.6.4.4b—Geosynthetic Reinforcements ............................................................................... 11-95 11.10.7—Seismic Design of MSE Walls ........................................................................................................... 11-97 11.10.7.1—External Stability ..................................................................................................................... 11-97 11.10.7.2—Internal Stability ...................................................................................................................... 11-99 11.10.7.3—Facing Reinforcement Connections ....................................................................................... 11-103 11.10.7.4—Wall Details for Improved Seismic Performance .................................................................. 11-104 11.10.8—Drainage ........................................................................................................................................... 11-106 11.10.9—Subsurface Erosion .......................................................................................................................... 11-106 11.10.10—Special Loading Conditions ........................................................................................................... 11-106 11.10.10.1—Concentrated Dead Loads .................................................................................................... 11-106 11.10.10.2—Traffic Loads and Barriers ................................................................................................... 11-109 11.10.10.3—Hydrostatic Pressures ........................................................................................................... 11-110 11.10.10.4—Obstructions in the Reinforced Soil Zone ............................................................................ 11-111 11.10.11—MSE Abutments ............................................................................................................................. 11-112 11.11—PREFABRICATED MODULAR WALLS ............................................................................................... 11-113 11.11.1—General ............................................................................................................................................. 11-113 11.11.2—Loading ............................................................................................................................................ 11-114 11.11.3—Movement at the Service Limit State ............................................................................................... 11-114 11.11.4—Safety against Soil Failure ............................................................................................................... 11-115 11.11.4.1—General ................................................................................................................................... 11-115 11.11.4.2—Sliding .................................................................................................................................... 11-115 11.11.4.3—Bearing Resistance ................................................................................................................. 11-115 11.11.4.4—Overturning ............................................................................................................................ 11-115 11.11.4.5—Subsurface Erosion ................................................................................................................ 11-116 11.11.4.6—Overall Stability ..................................................................................................................... 11-116 11.11.4.7—Passive Resistance and Sliding .............................................................................................. 11-116 11.11.5—Safety against Structural Failure ...................................................................................................... 11-116 11.11.5.1—Module Members ................................................................................................................... 11-116 11.11.6—Seismic Design for Prefabricated Modular Walls ............................................................................ 11-117 11.11.7—Abutments ........................................................................................................................................ 11-117 11.11.8—Drainage ........................................................................................................................................... 11-118 11.12—SOIL NAIL WALLS ................................................................................................................................. 11-118 11.12.1—General Considerations .................................................................................................................... 11-118 11.12.2—Loading ............................................................................................................................................ 11-120 11.12.3—Movement at the Service Limit State ............................................................................................... 11-122 11.12.4—Safety against Soil Failure (External and Overall Stability—Strength Limit State) ........................ 11-122 11.12.4.1—Sliding .................................................................................................................................... 11-122 © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 11-iv AASHTO LRFD BRIDGE DESIGN SPECIFICATIONS, NINTH EDITION, 2020 11.12.4.2—Overall Stability ..................................................................................................................... 11-122 11.12.5—Safety against Soil Failure (Internal and Compound Stability—Strength Limit State) .................... 11-123 11.12.5.1—Soil Shear Strength................................................................................................................. 11-123 11.12.5.2—Soil Nail Pullout ..................................................................................................................... 11-123 11.12.6—Safety against Structural Failure (Internal and Compound Stability—Strength Limit State) .......... 11-125 11.12.6.1—Soil Nail in Tension ............................................................................................................... 11-125 11.12.6.2—Soil Nail Wall Facing—Strength Limit State......................................................................... 11-126 11.12.6.2.1—General ......................................................................................................................... 11-126 11.12.6.2.2—Facing Flexure ............................................................................................................. 11-127 11.12.6.2.3—Facing Punching Shear Resistance .............................................................................. 11-130 11.12.6.2.4—Headed Stud in Tension ............................................................................................... 11-132 11.12.7—Seismic Design of Soil Nail Walls ................................................................................................... 11-133 11.12.7.1—External and Global Stability ................................................................................................. 11-133 11.12.7.2—Internal Stability ..................................................................................................................... 11-134 11.12.8—Corrosion Protection ........................................................................................................................ 11-134 11.12.9—Soil Nail Testing .............................................................................................................................. 11-136 11.12.10—Drainage ......................................................................................................................................... 11-136 11.13—REFERENCES ........................................................................................................................................... 11-137 APPENDIX A11—SEISMIC DESIGN OF RETAINING STRUCTURES ........................................................... 11-143 A11.1—GENERAL ................................................................................................................................................ 11-143 A11.2—PERFORMANCE OF WALLS IN PAST EARTHQUAKES................................................................... 11-143 A11.3—CALCULATION OF SEISMIC ACTIVE PRESSURE ............................................................................ 11-144 A11.3.1—Mononobe–Okabe Method .............................................................................................................. 11-144 A11.3.2—Modification of Mononobe–Okabe Method to Consider Cohesion ................................................ 11-146 A11.3.3—Generalized Limit Equilibrium (GLE) Method ............................................................................... 11-149 A11.4—SEISMIC PASSIVE PRESSURE ............................................................................................................. 11-149 A11.5—ESTIMATING WALL SEISMIC ACCELERATION CONSIDERING WAVE SCATTERING AND WALL DISPLACEMENT .................................................................................................................................................. 11-154 A11.5.1—Kavazanjian et al., (1997) ................................................................................................................ 11-155 A11.5.2—NCHRP Report 611—Anderson et al. (2008) ................................................................................. 11-155 A11.5.3—Bray et al. (2010), and Bray and Travasarou (2009) ....................................................................... 11-158 A11.6—APPENDIX REFERENCES ..................................................................................................................... 11-158 APPENDIX B11—DETERMINATION OF TMAX FOR MSE WALLS USING THE SIMPLIFIED METHOD ... 11-161 B11.1—GENERAL ................................................................................................................................................ 11-161 B11.2—DETERMINATION OF TMAX .................................................................................................................... 11-161 B11.3—APPENDIX REFERENCE ........................................................................................................................ 11-163 © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40 SECTION 11 WALLS, ABUTMENTS, AND PIERS 11-1 11.1—SCOPE This Section provides requirements for design of abutments and walls. Conventional retaining walls, nongravity cantilevered walls, anchored walls, mechanically stabilized earth (MSE) walls, prefabricated modular walls, and soil nail walls are considered. 11 11.2—DEFINITIONS Abutment—A structure that supports the end of a bridge span, and provides lateral support for fill material on which the roadway rests immediately adjacent to the bridge. In practice, different types of abutments may be used. These include: • Stub Abutment—Stub abutments are located at or near the top of approach fills, with a backwall depth sufficient to accommodate the structure depth and bearings which sit on the bearing seat. • Partial-Depth Abutment—Partial-depth abutments are located approximately at middepth of the front slope of the approach embankment. The higher backwall and wingwalls may retain fill material, or the embankment slope may continue behind the backwall. In the latter case, a structural approach slab or end span design must bridge the space over the fill slope, and curtain walls are provided to close off the open area. Inspection access should be provided for this situation. • Full-Depth Abutment—Full-depth abutments are located at the approximate front toe of the approach embankment, restricting the opening under the structure. • Integral Abutment—Integral abutments are rigidly attached to the superstructure and are supported on a spread footing or a deep foundation capable of permitting necessary horizontal movements. Anchored Wall—An earth retaining system typically composed of the same elements as nongravity cantilevered walls, and that derive additional lateral resistance from one or more tiers of anchors. Geogrid—A geosynthetic formed by a regular network of integrally connected elements with apertures greater than 0.25 in. to allow interlocking with surrounding soil, rock, earth, and other surrounding materials to function primarily as reinforcement. Geostrip—Polymeric material in the form of a strip (also sometimes called a polymer strap) of width not more than 8.0 in., used in contact with soil or other materials in geotechnical and civil engineering applications, or both. Geotextile—A permeable geosynthetic comprised solely of textiles. Mechanically Stabilized Earth Wall—A soil-retaining system, employing either strip- or grid-type, metallic, or polymeric tensile reinforcements in the soil mass, and a facing element that is either vertical or nearly vertical. Nongravity Cantilever Wall—A soil-retaining system that derives lateral resistance through embedment of vertical wall elements and supports retained soil with facing elements. Vertical wall elements may consist of discrete elements, e.g., piles, drilled shafts, or auger-cast piles spanned by a structural facing, e.g., lagging, panels, or shotcrete. Alternatively, the vertical wall elements and facing may be continuous, e.g., sheet piles, diaphragm wall panels, tangent-piles, or tangent drilled shafts. Pier—Part of a bridge structure that provides intermediate support to the superstructure. Different types of piers may be used. These include: • Solid Wall Piers—Solid wall piers are designed as columns for forces and moments acting about the weak axis and as piers for those acting about the strong axis. They may be pinned, fixed, or free at the top, and are conventionally fixed at the base. Short, stubby types are often pinned at the base to eliminate the high moments which would develop due to fixity. Earlier, more massive designs were considered gravity types. © 2020 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. RR-40 – CA received 8/22/25, Exhibit 40