Field Studies of Steel Girder Fit-Up

The fit condition of a steel I-girder bridge refers to the deflected geometry associated with a specific load condition in which the cross-frames or diaphragms are detailed to connect to the girders. There are three fit conditions for steel girder bridges: no-load fit (NLF), steel dead load fit (SDLF), and total dead load fit (TDLF). Consideration of the fit condition is important because the appropriate fit decision can provide significant benefit to the constructability and the overall performance of the bridge system. The American Association of State Highway and Transportation Officials (AASHTO) LRFD Bridge Design Specifications specify that the fit condition of the cross-frames or diaphragms should be clearly stated in the contract documents for straight I-girder bridges with skewed supports, and horizontally curved I-girder bridges with or without skewed supports. If the appropriate fit condition is not selected, the bridge could be subjected to problems during erection and construction. It could also result in systems that have errors in final steel vertical profile and cross-slope or other long-term problems. In 2016, the National Steel Bridge Alliance (NSBA) published a document titled “Skewed and Curved Steel I-Girder Bridge Fit.” The document provided guidelines for selecting the appropriate fit condition during design, however, it was based on analytical work and did not include field verifications. These guidelines have been accepted and are being used by bridge design engineers. Research is needed to validate these guidelines by conducting field measurements of existing steel girder systems to determine the condition of the girders relative to the design. The objective of this research is to investigate the effects of the as-detailed cross-frame fit condition (SDLF and TDLF) on the as-built girder geometry in the field. It shall be limited to I-shape plate girders.


  • English


  • Status: Proposed
  • Funding: $300000
  • Contract Numbers:

    Project 10-129

  • 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

  • Start Date: 20240226
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01898274
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 10-129
  • Files: TRB, RIP
  • Created Date: Nov 6 2023 4:54PM