Comparison of Post-Earthquake Highway Bridge Repair Costs

Abstract

Post-earthquake repair costs are useful for evaluating different bridge design options in a performance-based setting. For example, expected post-earthquake repair cost estimates together with the estimated cost of new construction provide transportation managers with a ratio useful for inventory assessment and post-disaster decision support. The derivation of post-earthquake repair cost involves assessment of expected site seismicity, bridge configuration and geometry, structure seismic response, failure modes, and available repair methods and associated costs. The repair cost probability distribution is derived using first and second moments from a simple graphical tool called Fourway. This tool uses three probabilistic models to evaluate repair costs based on the Pacific Earthquake Engineering Research Center’s performance-based earthquake engineering framework: (1) a probabilistic seismic demand model relating earthquake intensity measure to bridge response parameters, (2) a probabilistic damage model relating bridge demand to discrete damage states of key bridge components, and (3) a cost model relating damage states to the cost of available repair methods. This procedure is used to compare the post-earthquake repair costs of four design options for a reinforced concrete highway overpass bridge in California with four singlecolumn bents. Bridge design options are represented by different column heights and circular and oblong column cross-sections with different dimensions. The column choices produce different post-earthquake repair costs due to differing demand model parameters for each structural component. The total repair cost for each design option is computed by combining the individual costs for each component. Repair cost ratios are used to compare the design options.