Load Rating Examples and Changes to the AASHTO Manual for Bridge Evaluation for Concrete Segmental Post-Tensioned Box Girder Bridges

The objective is to develop a “Segmental Bridge Load Rating Guideline” based on real-world examples. These analyses will provide clear templates that will allow engineers to follow comprehensive procedures necessary to produce industry standard accurate load ratings for segmental box girders taking into account all pertinent variables. Concrete segmental box girder bridges have proven to be an efficient means for accomplishing a solution for long span bridges. However, due to the complexities involved with the section shape, reinforcement, construction type and continuity conditions a common solution for load rating these bridges is essential. There is a lack of understanding among owners and the consulting community about how to accurately load rate new and older concrete segmental box girder bridges. Concrete segmental box girder bridges were first constructed in the United States in the 1970s. The earliest concrete segmental box girder bridges were designed and load rated using methods that were often not codified by AASHTO, and differ significantly from the current AASHTO Load and Resistance Factor Design (LRFD) and Load and Resistance Factor Rating (LRFR). Many construction details used at that time are generally not used in the design and construction of today’s bridges; such as: fewer tendons in a cluster, open joints between precast segments in lieu of double faced epoxied joints, etc. As a result, the use of these details have resulted in significant reduction in capacity when evaluated using the current LRFR from the original load ratings. Current load rating criteria attempts to account for some of the details specific to segmental bridges, by including concrete tensile stresses in the calculation of the load rating at operating. However, applying these criteria to all segmental bridge types does not appear to be a consistent procedure for load rating concrete segmental bridges. As a result, there is a need to develop load rating criteria to accurately determine the load rating capacity of bridges designed in the time period before codification of the AASHTO LRFD and LRFR, to ensure safety and mobility. A search was done that showed previous research on the barrier effects on transverse loads and a project in Florida that produced a program to analyze the axle equivalent transverse loading for segmental bridges. This project will build upon these reports to provide a comprehensive guide with examples.

Language

  • English

Project

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

    Project 12-123

  • 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:

    Dekelbab, Waseem

  • Start Date: 20200811
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01739625
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 12-123
  • Files: TRB, RiP
  • Created Date: May 18 2020 3:06PM