The National Academies

NCHRP 20-07/Task 088 [Completed]

LRFD Specifications for Retaining Walls
[ NCHRP 20-07 (Research for AASHTO Standing Committee on Highways) ]

  Project Data
Funds: 65000
Research Agency: D'Appolonia
Effective Date: 9/2/1997
Completion Date: 12/31/1998
Comments: Completed

Task 88, FY 1997, "LRFD Specifications for Retaining Walls", (D'Appolonia, Engineering Division of Ground Technology, Inc., James Withium). The AASHTO LRFD Bridge Design Specifications were implemented in 1994. The most recent revision to these specifications was published in 1996. Section 3, especially Article 3.11, and Section 11, contain the LRFD provisions for lateral earth pressures and retaining wall design. Other articles in Section 3 also contain definitions and required load factors which affect retaining wall design. The LRFD provisions for retaining walls are based on the allowable stress design methods in the 1996 AASHTO Standard Specifications for Highway Bridges. These 1996 Standard Specifications for retaining walls (Sections 5 and 7 of Division I and Section 7 of Division II) were recently rewritten and will be published in the 1997 interim AASHTO specifications. Because the rewrite of Sections 5 and 7 of the AASHTO Standard Specifications has resulted in substantial changes to that portion of the AASHTO code, the LRFD specifications for retaining walls, specifically the pertinent articles of Section 3 and all of Section 11, must be rewritten to reflect those changes.

The objective of this task is to prepare a rewrite of articles of Section 3 and all of Section 11 of the 1994 AASHTO LRFD Bridge Design Specifications and the 1996 Interim Specifications which address retaining wall design. The document produced shall be suitable for adoption by the AASHTO Highway Subcommittee on Bridges and Structures. Calibration of the resistance factors for retaining wall design will also be an objective of this task. The research agency's work is complete. The recommended specification has been referred to Technical Committee T-15, "Substructures and Retaining Walls," of the AASHTO Highway Subcommittee on Bridges and Structures. (NCHRP Staff: D.B. Beal)

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