Investigation of Shear Capacity in Girders with Undersized Transverse Stiffeners

The design of transverse shear stiffeners in steel plate girder bridges has changed over the years. Earlier AASHTO Standard Specifications and AASHTO Bridge Design Specifications (BDS) required transverse stiffeners to have sufficient flexural rigidity to develop the shear buckling resistance of a steel girder web. The current AASHTO Load and Resistance Factor Design Bridge Design Specifications (LRFD BDS) use a different approach based on minimum geometric dimensions of the stiffener. This change affects the load rating of older bridges that do not meet current criteria. The AASHTO LRFD BDS and the AASHTO Manual for Bridge Evaluation (MBE) do not include provisions for determining the shear capacity of girders with undersized stiffeners or the effectiveness of an undersized stiffener. In current practice, load rating engineers may assume existing undersized transverse stiffeners are adequate based on inspection or original design practice; however, when these stiffeners are evaluated against current geometric requirements, even slightly undersized stiffeners may be treated as ineffective, and the girder may be rated as unstiffened. This can significantly reduce the calculated shear resistance of the girder and may result in unnecessary strengthening, load posting, or bridge closure. Engineering judgment indicates that slightly undersized stiffeners may still provide some resistance; however, there is currently no mathematical basis or load rating procedure to quantify that resistance. Therefore, research is needed to investigate the resistance of steel girders with undersized transverse stiffeners. This research would help state departments of transportation (DOTs) and bridge owners more accurately evaluate existing steel girder bridges, reduce unnecessary load postings or strengthening, and extend the service life of bridges that have reserve capacity. OBJECTIVE: The objective of this research is to develop load rating provisions for bridges with undersized transverse stiffeners. The research should be presented through a white paper with proposed revisions to the AASHTO MBE.

• Record URL:
  • http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=6041

Language

• English

Project

• Status: Proposed
• Funding: $900,000.00
• Contract Numbers:

  10-159

• 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: 20261001
• Expected Completion Date: 0
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Girder bridges; Load and resistance factor design; Shear strength; Transverse stiffeners
• Subject Areas: Bridges and other structures; Design; Highways; Maintenance and Preservation; Materials;

Filing Info

• Accession Number: 01991750
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: 10-159
• Files: TRB, RIP
• Created Date: Jun 2 2026 3:10PM