Influence of Corrosion Deterioration on Lifetime Seismic Resilience of Highway Bridges

Highway bridges across the globe have demonstrated vulnerability to damage during earthquake events. While earthquakes occur infrequently, environmental degradation mechanisms such as chloride-induced corrosion deterioration are continuous and decrease the structural performance over time. There is a need to assess the performance of existing older bridges in India, taking into account the combined threats of corrosion degradation and seismic hazard. In this regard, resilience has emerged as a powerful tool to determine the bridge performance integrating the seismic vulnerability, losses, and recovery functions. This study presents a case-study for lifetime resilience assessment considering the effect of environmental and seismic hazards using a representative two-span semi-integral bridge. Finite element models of the bridge is developed at pristine and four degraded conditions considering chloride-induced corrosion. Nonlinear time-history analyses are conducted on the bridge models to develop time-dependent seismic fragility curves. Further, these fragility curves are used to estimate post-earthquake direct and indirect losses that are combined with suitable recovery models to estimate the functionality and resilience of the bridge. Results obtained from the analysis revealed a degrading trend of the resilience of the bridge as it deteriorates with age, representing the significance of lifetime seismic resilience assessment for estimating the performance of existing aging bridges.