Life-Cycle Risk Assessment of Spatially Distributed Aging Bridges under Seismic and Traffic Hazards

Abstract

This paper presents a rational framework for the quantitative assessment of life-cycle risk of bridges within a transportation network. Bridge vulnerability is evaluated with respect to seismic and abnormal traffic hazards. The effects induced by seismic hazard are investigated by means of fragility analysis. Random earthquakes are generated using Latin Hypercube sampling technique, and probabilities of exceeding specific structural damage states are computed for each specific seismic scenario. Traffic hazard is assessed considering Weibull distributed time-to-failure of the bridge superstructure. Epistemic and aleatory uncertainties are accounted for in order to provide a rational assessment of life-cycle risk. Consequence analysis includes different levels of bridge serviceability (fully serviceable, partly serviceable, closed, and collapsed), and monetary values are used to evaluate direct and indirect consequences. Seismic risk, traffic-induced risk, and total risk are evaluated for a group of existing bridges located north of the San Diego metropolitan area.