Probabilistic long-term resilience of bridges under seismic and deterioration processes

Accurate long-term risk and resilience assessments of bridges are of paramount importance to aid rational decision making under seismic hazards. Both earthquakes and structural deterioration exhibit time-varying features. It has been found that the occurrence of large earthquakes is dependent on time, due to energy accumulation, whereas the widely adopted homogeneous Poisson process assumes a time-independent hazard occurrence. Bridges can deteriorate over time due to environmental exposure, resulting in increased seismic vulnerability. The time-varying characteristics associated with earthquakes and deterioration, which have compound effects on structures, should thus be incorporated in long-term seismic risk and resilience assessments. An approach for assessing the long-term resilience of bridges incorporating the time-varying characteristics of earthquakes and deterioration is presented. The Brownian passage time model, capturing energy accumulation and release, is used to model the time-varying characteristics of earthquakes. Bridge seismic vulnerability is computed in a time-varying manner considering deterioration. Subsequently, long-term bridge resilience loss is computed by considering earthquakes and deterioration over the entire service life of the bridge. The proposed approach is illustrated on a highway bridge subjected to time-dependent seismic hazard and structural deterioration.