Assessment and Evaluations of I-80 Truck Loads and Their Load Effects: Final Report

Details

• Creators:
  Barker, Michael ; Puckett, Jay A.
• Corporate Creators:
  BridgeTech, Inc.
• Corporate Contributors:
  Wyoming. Department of Transportation
• Subject/TRT Terms:
  • Load factor
  • Loads
  • Pavement performance
  • Trucks
  • Weigh in motion Bridge design
  • live load
  • calibration
  • reliability
  • bridge analysis
  • live load factor
  More +
• Publication/ Report Number:
  FHWA - WY - 17/02F
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States;Wyoming
• Edition:
  Final report
• Corporate Publisher:
  Wyoming. Department of Transportation
• Abstract:
  The research objective is to examine the safety of Wyoming bridges on the I-80 corridor considering the actual truck traffic on the ; interstate based upon weigh in motion (WIM) data. This was accomplished by performing statistical analyses to determine reliability indices for a ; set of archetype bridges. This set of bridges include simple-span bridges with lengths between 30 ft and 200 ft (positive moments) and two-span ; bridges with equal spans lengths of 30 ft to 200 ft (negative moments). Adequate safety, as defined by AASHTO Bridge Specifications, is a ; reliability index of at least 3.50. Wyoming DOT has several years of truck characteristics that were used to develop a live load model in a manner ; similar to the NCHRP used to calibrate the LRFD Specifications. The results are the live load bias values and coefficients of variations for the ; different bridge archetypes that are used to determine the 75-year maximum load statistical properties for the reliability analyses. ; Three optimally designed steel bridges from the NCHRP 20-7/186 report with varying ratios of dead, wearing surface, and live loads are used to ; perform the reliability analyses and assess safety. Truck traffic along I-80 creates more demand than that assumed in the AASHTO LRFD bridge ; design procedures. The greater demand results in reliability indices that do not meet target safety levels and have reliability indices significantly ; less than 3.5. Two issues should be addressed: (1) the unacceptably low reliability indices for short multi-span bridges (2) the overall low reliability ; indices for all span lengths. ; The “optional” (low-boy) dual tandem load where there is a tandem in adjacent spans in the AASHTO LRFD commentary significantly increases ; the negative design live load moments. Using the dual tandem, the reliability indices for the shorter two-span bridges increase to 3.00 and above, ; placing this bridge type into the range of the reliability indices for the other bridge span lengths. However, indices are below the target. Raising ; the design live load factor, yL, directly and fairly uniformly increases reliability indices. An increase in yL to 2.00 (from 1.75) increases almost all of ; the reliability indices above 3.50. ; In summary, the “optional” low boy load should be used for design and will control shorter multiple-span bridges in the negative moment region. ; Alternatives to address this situation are outlined.
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• Format:
  PDF
• Funding:
  RS03(214)
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/32469/dot_32469_DS1.pdf
• File Type:
  [PDF - 1.07 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:dcb384c37f5b13f4edac1a8615fd889e3e275b26b2438a5ae9194f4fe69b42aef10503d380931a9f1964780adf113f63f92f9b3337e18631ef6fe3b678dc2edb