Proposed AASHTO Specifications for Design of Piles for Downdrag

The AASHTO LRFD Bridge Design Specifications recognize that piles in settling soil experience downdrag forces from negative skin friction and may also move downward with the adjacent soil. Many bridges are constructed in areas where there is compressible soil or liquefiable soil, which necessitates the consideration of downdrag forces and associated settlement. Downdrag for static conditions as well as seismic conditions has increasingly placed greater demands on existing and new foundations and also led to higher construction costs. Therefore, there is an immediate need to review the fundamental behavior of piles subject to downdrag and propose design specifications for the implementation of the neutral plane method for the evaluation of downdrag and the static and seismic design of piles. The objectives of this research were to (1) propose modifications to the AASHTO LRFD Bridge Design Specifications for the static and seismic design of piles for downdrag and (2) develop design examples to demonstrate the application of the proposed design specifications.

• Record URL:
  http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=4567
• Supplemental Notes:
  • Further work will be conducted under NCHRP 12-116A in 2020.

Language

• English

Project

• Status: Completed
• Contract Numbers:

  Project 12-116

• Sponsor Organizations:

  American Association of State Highway and Transportation Officials (AASHTO)

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

  National Cooperative Highway Research Program

  Transportation Research Board
  500 Fifth Street, NW
  Washington, DC  United States  20001

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Project Managers:

  Dekelbab, Waseem

• Performing Organizations:

  Brigham Young University

  Provo, UT  United States  84602-4081
• Principal Investigators:

  Rollins, Kyle

• Start Date: 20190627
• Expected Completion Date: 20191121
• Actual Completion Date: 20191121

Subject/Index Terms

• TRT Terms: Bridge design; Drag forces; Earthquake resistant design; Load and resistance factor design; Piles (Supports); Specifications
• Identifier Terms: AASHTO LRFD Bridge Design Specifications
• Subject Areas: Bridges and other structures; Design; Highways;

Filing Info

• Accession Number: 01672544
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: Project 12-116
• Files: TRB, RIP
• Created Date: Jun 19 2018 9:39AM