Resilience and Economic Loss Assessment of Highway Bridges in Deep Reservoir under Near-Fault Ground Motions

Bridges located in deep reservoir are exposed to threats from near-fault ground motions. The resilience and economic loss of a highway bridge in deep reservoir under near-fault ground motions require better understanding. This study incorporated the existing resilience and economic loss assessment framework with the effect of post-earthquake underwater repair. The methodology was illustrated to evaluate the seismic performance of an example highway continuous rigid-frame bridge in deep reservoir. The three-dimensional nonlinear numerical model of the example bridge was built with the hydrodynamic added mass estimated by the fluid-structure interaction model. Two types of near-fault ground motions, the forward-directivity and fling-step ground motions, were selected to conduct the nonlinear seismic analyses of the bridge. The fragilities of the piers, bearings, and the bridge system were assessed and resilience and economic loss of the example bridge under different types of near-fault ground motions were evaluated and compared. It can be concluded from the studies that: (1) the peak ground velocity (PGV) is suggested to be taken as the intensity measures of ground motions for the probabilistic seismic demand models of the bridge in deep reservoir; (2) the fling-step ground motions caused larger pier, bearing, and system damage probability, but lower resilience and bigger economic loss than the forward-directivity ground motions; (3) the structural resilience decreases, whereas the economic loss increases with the increasing water level; and (4) the highest water level and the fling-step ground motions result in the worst performance of the example highway bridges in deep reservoir near active faults. The framework not only aids engineers to better understand the seismic performance, but also assists in the decision-making of post-event rehabilitation activities for the highway bridges in deep reservoir.