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Mid-America Transportation Center

Protocol For Evaluation of Existing Bridges

Final Report
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Researchers

  • Principal Investigator: Maria Szerszen (mszerszen2@unl.edu 402-472-8069)
  • Project Status
    Complete
    About this Project
    Brief Project Description & Background
    The project is focused on thrust areas of the transportation network. The resulting guide for field-testing will provide a tool for practical evaluation of bridges and the decision-making process.
    Research Objective
    The proposed project will develop protocols for evaluation of existing bridges that will include verification of the load distribution factors, actual live load, dynamic load factors, minimum load carrying capacity or fatigue load spectra. The available field-testing procedures will be presented and described. Protocols will include description of the required equipment and operational guides.
    Potential Benefits
    The proposed project will result in a guide with protocols (procedures) for evaluating existing bridges. The guide will be prepared according to the national standards required by AASHTO and FHWA, and will be ready to use for rating bridges. Bridges can be placed into categories from the point of view of evaluation needs. The guide will include bridge selection criteria for analytical evaluation and field-testing. For each procedure, a list of required equipment will be provided, and other special requirements will be given. Practical procedures will be formulated for the evaluation and verification of actual load carrying capacity, actual load distribution factors, and actual dynamic load factors. The guide will include examples with case studies.
    Abstract
    The proposed project will develop protocols for evaluation of existing bridges. The proposed research will involve identification of problems to be addressed — for example, verification of the load distribution factors, actual live load (weight of trucks), dynamic load factors, minimum load carrying capacity, or fatigue load spectra. The available field-testing procedures will be presented and described. The developed protocols will include description of the required equipment and operational guides. The protocols will also include the assessment of accuracy, potential problems, and best practice observations. The field tests will include the measurement of strain and deflection, with the objective of determining/verifying the dynamic load factor, girder distribution factor, and minimum load carrying capacity. Field-testing will be applied to pre-selected representative structural types and materials, so that the obtained results can be applied to a wider population of bridges. Field-testing will involve instrumentation using strain gauges and LVDT’s, a power generator, and a data acquisition system. The test load will be considered in the form of test trucks. For proof loading, it is efficient to use military tanks (acquirable from local National Guard). The developed protocols will be demonstrated on three selected bridges. The structures will be selected in cooperation with NDOR. Field tests will be performed to verify the live load distribution factor, dynamic load factor, and minimum load carrying capacity by proof load test.
    Project Amount
    $ $60,964