Earthquake-Induced Bridge Displacements

Most bridges respond inelastically to large seismic demand. However, seismic design using the AASHTO LRFD Bridge Design Specifications and the AASHTO Guide Specifications for LRFD Seismic Bridge Design methodologies relies on an elastic analysis to estimate the inelastic demands using the “equal displacement approximation.” The equal displacement approximation, introduced over 60 years ago, has not been fully validated. Advances in numerical and physical methods suggest that the equal displacement approximation underestimates the “real” seismic displacement demands. Consequently, bridges may not perform as intended when using the elastic analysis methods used for most designs. The potential underestimation associated with the AASHTO provisions was verified by the recently completed NCHRP Project 12-106, “Proposed Guidelines for Performance-Based Seismic Bridge Design.” Research is needed to examine the equal displacement approximation and, if necessary, develop simple, reliable adjustment factors that can modify the elastic displacement predictions to better match the “real” inelastic displacement response. The research outcome should provide the basis for design recommendations to better predict seismic demands resulting in safer and more reliable bridges. The objective of the research is to develop robust yet simple procedures for calculation of inelastic displacement demands in bridges subject to earthquake demands.


  • English


  • Status: Active
  • Funding: $400000
  • Contract Numbers:

    Project 12-125

  • Sponsor Organizations:

    National Cooperative Highway Research Program

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

    American Association of State Highway and Transportation Officials (AASHTO)

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

    Federal Highway Administration

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

    Abu-Hawash, Ahmad

  • Performing Organizations:

    Modjeski & Masters, Incorporated

    P.O. Box 2345
    Harrisburg, PA  United States  17105-
  • Principal Investigators:

    Murphy, Thomas

  • Start Date: 20240116
  • Expected Completion Date: 20270115
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01846785
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 12-125
  • Files: TRB, RIP
  • Created Date: May 24 2022 7:54PM