Determination of barge impact probabilities for bridge design.

Details

• Creators:
  Consolazio, Gary R. ; Kantrales, George C.
• Corporate Creators:
  University of Florida. Dept. of Civil and Coastal Engineering
• Corporate Contributors:
  Florida. Dept. of Transportation. Research Management Center
• Subject/TRT Terms:
  • Bridge waterways
  • Barges
  • Risk assessment
  • Bridge design
  • Collisions
  • Impact loads
  • Aberrancy rate
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Florida
• Corporate Publisher:
  University of Florida. Department of Civil and Coastal Engineering
• Abstract:
  Waterway bridges in the United States are designed to resist vessel collision loads according to design provisions released by the American Association of State ; Highway and Transportation Officials (AASHTO). These provisions provide detailed procedures for calculating design vessel impact loads within the context of a ; comprehensive risk assessment. One of the primary subcomponents of this process is the calculation of probabilities that estimate the likelihood that a barge-to-bridge impact ; event will occur. However, the expressions used to predict the frequency of barge-to-bridge collisions were developed from a limited number of data sets. Furthermore, the ; technology employed by the maritime industry at the time the original AASHTO provisions were developed—in the early 1990s—has been significantly improved in ; subsequent decades. As a consequence of these factors, current estimates of barge-to-bridge collision probabilities may differ from presently-employed AASHTO estimates. ; The focus of the research described in this report was the development of a revised barge impact probability expression particularly applicable for the design of bridge ; structures located on Florida waterways. Specifically, the existing AASHTO expression for the base aberrancy rate (BR)—used to estimate the likelihood that a barge flotilla ; will stray from the intended transit path—was recalibrated and updated. Barge flotilla traffic data and barge-to-bridge collision (casualty) data for Florida bridge locations ; were collected and used to compute historical barge-to-bridge collision probabilities. These probabilities were then utilized in conjunction with additional supplementary ; parameters specified in AASHTO—quantified using bridge site-specific information—to back-calculate BR values for each bridge location. A subset of BR estimates from ; several bridge sites were then utilized to produce a single design value of BR that may be used in risk assessments for new and existing bridge structures. Based on results ; from the recalibration process, the updated BR estimate was 55% smaller than the current value prescribed by AASHTO. To demonstrate the effect of the recalibrated BR ; parameter, annual frequency (AF) of collapse values from risk assessments of two previously-investigated bridge structures—the Bryant Grady Patton Bridge (Apalachicola ; Bay, FL) and the LA-1 Bridge (Leeville, LA)—were recomputed using the updated BR expression. Despite the reduction in BR, values of AF estimated using UF/FDOT ; methods and the updated BR expression remained high relative to AF estimates produced by existing AASHTO methods. It was noted in this study that bridge locations with ; low volumes of barge traffic corresponded to high estimates of BR. This finding was a consequence of utilizing less data in the statistical calibration process, which reduced ; the accuracy of the resulting predictions. Consequently, only Florida bridge locations with significant levels of barge flotilla traffic were utilized to produce the recommended ; design value of BR. However, additional out-of-state locations exist with more highly trafficked bridge locations, as well as a more comprehensive source of barge traffic ; data. Inclusion of such locations in a similar recalibration effort could result in a lower design value of BR.
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• Format:
  PDF
• Funding:
  BDV31-977-21
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/31010/dot_31010_DS1.pdf
• File Type:
  [PDF - 4.03 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:3ffa9a26cfe5caae40a0b42639e0aa2e826f832501971e76e4103061e195aabf