Seismic performance assessment of an existing multispan bridge in eastern Canada retrofitted with fiber reinforced elastomeric isolator

A seismically resilient transportation network entails preprioritized retrofit plans for conventionally designed highway bridges. This is particularly important for the province of Ontario in Canada, where more than 44% of the multispan bridges have been constructed prior to 1970. To support future seismic risk mitigation efforts, this study evaluated the seismic performance of a multispan continuous reinforced concrete bridge in Ontario, Canada, in its as-built and retrofitted conditions. Seismic retrofit is conducted utilizing novel Fiber Reinforced Elastomeric Isolators (FREIs). Analytical fragility curves are developed using Incremental Dynamic Analysis (IDA) on a three-dimensional nonlinear finite element model of the bridge using 45 synthetic ground motion records for eastern Canada. Results indicate that seismic isolation can effectively mitigate the seismic demand on columns and transfer the shear forces to the end abutments resulting in excessive backfill soil deformation. However, this deformation does not necessarily result in bridge failure and traffic disruption.