Life-Cycle Resilience of Aging Bridges under Earthquakes

A quantitative framework was developed to assess life-cycle resilience of deteriorating reinforced concrete (RC) bridges under seismic ground motions (GMs). Deterioration of a three-span RC bridge due to chloride-induced corrosion was considered, and three-dimensional (3D) finite-element (FE) models of the bridge were generated at pristine and four degraded conditions. Nonlinear time history analyses of bridge models were performed to develop time-variant bridge fragility curves, which were utilized further to estimate postearthquake direct and indirect losses arising from bridge damage and associated downtime. Sigmoidal functions were used to numerically simulate realistic recovery paths depending on the extent of bridge damage after earthquakes. Finally, bridge resilience was estimated by integrating the bridge's seismic vulnerability, losses, and recovery functions. Obtained results revealed a degrading trend of resilience of the bridge as it aged, signifying the importance of considering a life cycle-oriented framework for estimating time-variant resilience of aging bridges. At a specific state of degradation, bridge resilience was observed to reduce linearly or nonlinearly with increasing GM intensity or peak ground acceleration (PGA). Finally, an uncertainty analysis with key uncertain input parameters showed resilience of the pristine bridge at any specific PGA to vary following a normal distribution.