Research for AASHTO Standing Committee on Highways. Task 316. Establishment of Appropriate Guidelines for Use of the Direct and Indirect Design Methods for Reinforced Concrete Pipe

Currently, in the American Association for State Highway and Transportation Officials (AASHTO) load and resistance factor design (LRFD) Bridge Design Specifications, reinforced concrete pipe can be designed according to one of two methods; the indirect design method, or the direct design method. The Indirect Design Method (IDM) uses tables to select pipe class (thickness, reinforcement, and concrete strength) for a given fill height and installation type. The method is based on three-edge-bearing (TEB) tests. The Direct Design Method (DDM) Method is a more theoretical design method where four separate structural design limit states are considered: flexure, shear (diagonal tension), radial tension, and crack control. These two methods may give different answers for design of equivalent pipe, depending upon size and installation requirements. The IDM is based on a comparison of field moments versus test moments, and may be an overly conservative simplification when flexure criteria are not the governing limit state. The DDM has simplifying assumptions for reinforcement conditions, as well as limitations on the steel and concrete properties that may not allow for a pipe to be designed to its true strength. Thus, an inappropriate selection of design method can result in unneeded expense. Recent suggestions for determining appropriate guidelines for which design method to use have ranged from taking the lower steel area requirement of the two designs, to using the DDM for pipe larger than 36" and the IDM for pipe 36" and smaller. The objectives of this research were to: (1) review the strengths and weaknesses of the IDM and DDM (2) recommend guidelines for when each method is most appropriate for use; and (3) recommend revisions to the AASHTO LRFD Bridge Design Specifications, Section 12.


  • English


  • Status: Completed
  • Contract Numbers:

    Project 20-07, Task

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway & Transportation Officials

    444 North Capitol Street, NW, Suite 225
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Performing Organizations:

    Queen's University, Ontario

    Department of Civil Engineering
    Kingston, Ontario  Canada  K7L 3N6
  • Principal Investigators:

    Moore, Ian

  • Start Date: 20121002
  • Expected Completion Date: 0
  • Actual Completion Date: 20140331
  • Source Data: RiP Project 37899

Subject/Index Terms

Filing Info

  • Accession Number: 01545237
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 20-07, Task
  • Files: TRB, RiP
  • Created Date: Nov 26 2014 1:00AM