Condition Evaluation of Precast Post-tensioned Concrete Girder Bridges During Fires from Distributed Fiber Optic Sensors

In the past few years, the research team has instrumented three full-scale concrete slab on steel beam composite floor specimens with distributed fiber optic sensors using pulse pre-pumped Brilliouin optical time domain analysis (PPP-BOTDA). Cost-effective single-mode optical fibers were used as distributed sensors for strain measurements when not sheathed with protective layers and for temperature measurements when sheathed with protective layers. Each specimen was prepared in the National Fire Laboratory and tested under combined mechanical and thermal loading by the National Institute of Standards and Technology. Technical challenges discovered during data process and analysis include: (1) uncertain interfacial bond condition between optical fibers and their surrounding concrete as fire gradually melts or burns off the protective layers of the fibers, (2) slow measurement process (e.g., 2 minutes) for the understanding of fire dynamics effect, and (3) interactive effect of multiple cracks on strain and temperature discrimination. This project aims to further understand the behavior of interfaces between optical fibers and their surrounding concrete with or without the effect of protective layers, reduce measurement times using the concept of compressive sensing, and develop and validate the distributed sensing approach for monitoring of the prestress loss in grouted and non-grouted steel tendons in post-tensioned concrete girders under fire conditions. The scope of work includes (1) Effect of the protective layers and deployment schemes of a temperature sensor on potential binding of the optical fiber with its surrounding concrete at high temperatures, (2) Detectability of interactive concrete cracks from distributed strain sensors, (3) Rapid monitoring of the prestress loss in steel tendons in concrete girders, and (4) Implementation and validation of distributed fiber optic sensors in a large-scale two-girder supported bridge deck under combined dead load and fire conditions.

    Language

    • English

    Project

    • Status: Active
    • Funding: $287025
    • Contract Numbers:

      69A3551747107

    • Sponsor Organizations:

      Office of the Assistant Secretary for Research and Technology

      University Transportation Centers Program
      Department of Transportation
      Washington, DC  United States  20590
    • Managing Organizations:

      Mid-America Transportation Center

      University of Nebraska-Lincoln
      2200 Vine Street, PO Box 830851
      Lincoln, NE  United States  68583-0851
    • Project Managers:

      Stearns, Amy

    • Performing Organizations:

      Missouri University of Science & Technology, Rolla

      Department of Engineering
      202 University Center
      Rolla, MO    65409
    • Principal Investigators:

      Chen, Genda

    • Start Date: 20210101
    • Expected Completion Date: 20220630
    • Actual Completion Date: 0
    • USDOT Program: University Transportation Centers
    • Source Data: RiP Project 91994-84

    Subject/Index Terms

    Filing Info

    • Accession Number: 01762022
    • Record Type: Research project
    • Source Agency: Mid-America Transportation Center
    • Contract Numbers: 69A3551747107
    • Files: UTC, RIP
    • Created Date: Jan 7 2021 12:25PM