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Mid-America Transportation Center

NDOR Bottom Flange Reinforcement in NU-I Girders

Final Report
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Researchers

  • Principal Investigator: George Morcous (gmorcous2@unl.edu 402-554-0571)
  • Co-Principal Investigator: Maher Tadros (mtadros1@unl.edu 4025544842)
  • Co-Principal Investigator: Kromel Hanna (kromelhanna@mail.unomaha.edu
  • Project Status
    Complete
    Sponsors & Partners
  • Nebraska Department of Roads
  • Research Objective
    The main objective of this research is to theoretically investigate the effect of the difference between the current NDOR bottom flange reinforcement detail and that requirement by AASHTO Load and Resistance Factor Design (LRFD) specifications on the structural performance of NU-I girders.
    Abstract
    Section 9.22.2 of the 1996 AASHTO Standard Specifications for Highway Bridges states that “For at least the distance d from the end of the beam, where d is the depth of the beam, nominal reinforcement shall be placed to enclose the prestressing steel in the bottom flange”. The requirement does not specify neither the size nor spacing of the bottom flange reinforcement. Therefore, the NU-I girders developed in the mid 1990’s by bridge engineers from Nebraska Department of Roads (NDOR) and researchers from the University of Nebraska-Lincoln (UNL) were detailed conservatively using welded wire reinforcement D4 @ 4 in. spacing along the full length of the girder of the girder depth.: The main objective of this research is to theoretically investigate the effect of the difference between the current NDOR bottom flange reinforcement detail and that requirement by AASHTO LFRD specifications on the structural performance of NU-I girders.
    Project Amount
    $ 29,754