Seismic resilience assessment of unbonded laminated rubber bearing supported highway bridges considering high variability of residual displacement

Post-earthquake residual bearing displacement is the primary earthquake-induced damage of highway bridges supported by unbonded laminated rubber bearings (ULRBs) and characterised by high variability, which is a critical damage indicator for the seismic resilience assessment of bridges. However, achieving a high-fidelity, computationally efficient seismic resilience assessment of ULRB-supported highway bridges that adequately accounts for the stochastic nature of residual displacement remains challenging. This study investigates the seismic behaviour and residual displacement characteristics of a ULRB‑supported highway benchmark bridge through numerical analyses that include girder–abutment pounding, structural parameter uncertainty, and record‑to‑record variability. Next, a high‑fidelity, computationally efficient fragility‑based method for estimating residual bearing displacement is proposed for use in seismic resilience assessment. The proposed method is compared with classical incremental dynamic analysis (IDA) and cloud approaches. Finally, the seismic resilience of the benchmark bridge, quantified as equivalent downtime, is evaluated using an expert‑survey‑based bridge functionality recovery model. Results show that the residual bearing displacement of ULRB-supported bridges exhibits considerable stochasticity than peak girder and bearing displacements. The fragility-based residual bearing displacement estimation method proposed in this study for the seismic fragility and resilience assessment of ULRB-supported bridges balances the accuracy and computational costs, generally outperforming the IDA and cloud methods.