Hazard-Based Risk and Cost-Benefit Assessment of Temporary Bridges in California

Details

• Creators:
  Petrone, Floriana ; Kunnath, Sashi K. ; Kashizadeh, SeyyedMahdi
• Corporate Creators:
  University of Nevada, Reno. Department of Civil and Environmental Engineering ; University of California, Davis. Department of Civil and Environmental Engineering
• Corporate Contributors:
  California. Department of Transportation
• Subject/TRT Terms:
  Assessments Benefit Cost Analysis Bridges Design Design Return Period Flexural Strength Hazard-Consistent Seismic Design Hazard Analysis Lightweight Materials Lightweight Superstructure Performance Risk Seismicity Seismic Risk Superstructures Temporary Bridges

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• Publication/ Report Number:
  CA25-3945
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Edition:
  Final Report 6/1/2022 to 5/31/2024
• Corporate Publisher:
  California. Department of Transportation
• Abstract:
  Temporary bridges are systems designed for an expected service life of 5 years. In 2011, the California Department of Transportation issued a memo to designers advocating the use of design spectra corresponding to a return period of 100 years for temporary bridges. However, broad consensus on the most appropriate hazard level and design approach is yet to be achieved. This study carries out fragility and risk analyses across a range of hazard levels, bridge life spans, and locations of different seismicity in California to provide recommendations to achieve a performance-based and hazard-consistent design for temporary bridges. Bridges systems with lightweight superstructures are first designed for three hazard levels corresponding to 50, 100, and 200-year return periods at four sites in California based on the site-specific seismic demands obtained from the U.S. Geological Survey maps and the Caltrans Seismic Design Criteria without meeting the AASHTO minimum reinforcement requirements. The sites include San Francisco, Los Angeles, San Luis Obispo, and Sacramento. Fragility and risk calculations are carried out to assess the attainment of a set of damage states currently adopted by Caltrans. Results demonstrate that a hazard-based design can ensure satisfactory performance with damage limited to minor concrete cover spalling to large concrete cover spalling and extensive flexural cracks, even when the design minimum requirements for ordinary bridges are not met. In addition, a baseline bridge model meeting the AASHTO (2020) and Caltrans (2019) minimum reinforcement requirements was used to identify the level of hazard resulting in Life Safety performance level, herein defined as the initiation of concrete core damage and longitudinal bar bucking. It was established that if a 200-year return period is targeted as the design return period for temporary bridges, the performance of the ‘minimum design’ bridge across the considered locations is satisfactory, with a probability of exceeding extensive flexural cracks and relatively large concrete cover spalling that substantially decreases for the locations with lower seismic hazard. Finally, an explicit comparison of the seismic risk for the bridges designed for 100 and 200-year return periods was carried out, showing that the risk is slightly affected by the change in the design return period from 100 to 200 years, thereby confirming the adequacy of the current recommendation of 100 years as the target return period when minimum design requirements are relaxed.
• Format:
  PDF
• Funding:
  65A0774 TO 006
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:c166836f684d57443c3e8f48a05c109734819b8abc9cf2a88a7a31874298d5e88d2b21451a4a988f7b8e5b119e08c9ea6f9663b13d26a5b54ea52b231b681f73
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/87054/dot_87054_DS1.pdf
• File Type:
  [PDF - 11.68 MB ]