Advancing seismic resilience: an innovative performance-based methodology for evaluating bridge seismic performance with soil-structure interaction considerations

Seismic events pose a significant threat to the structural integrity of bridges, often exacerbated by inadequate consideration of nonlinear responses and soil-structure interaction (SSI) effects.Existing guidelines for assessing bridge collapse risks lack practical and comprehensive approaches, hindering effective design and retrofitting strategies.This paper introduces an innovative, performance-based seismic evaluation framework tailored to bridge structures, inspired by the FEMA P695 methodology.The proposed approach integrates advanced seismic hazard analysis, nonlinear structural modeling, and statistical evaluation of collapse risks, incorporating ground motion spectral shape effects and system uncertainties.The methodology was applied to the Meloland Road Overcrossing (MRO) in Southern California as a case study.Four discrete archetype models, each with varying levels of SSI representation, were developed and subjected to incremental dynamic analysis (IDA) using a suite of 22 ground motions.These models ranged from simplified SSI representations to a detailed model (D4) explicitly accounting for abutment-soil and pile-soil interactions.Results reveal that the level of SSI representation significantly influences collapse behavior.The D4 model, with detailed SSI features, exhibited higher collapse probabilities and lower collapse margin ratios than simplified models, underscoring the critical role of SSI in structural performance.Fragility curves demonstrated the interplay of ground motion characteristics and SSI modeling on failure sequences and global collapse predictions, highlighting the necessity of accurate SSI characterization in seismic evaluations.This methodology supports resilient bridge design and retrofit planning in seismic zones.