ABSTRACT
Conventional fragility evaluations often neglect soil-structure interaction (SSI), treating structures as fixed-base. This study develops comprehensive seismic fragility curves for mid-rise RC residential buildings that explicitly incorporate SSI for more accurate vulnerability assessment. We compared three modeling approaches: fixed-base, simplified sway-rocking soil springs, and a detailed finite element model using solid elements for a two-layer soil profile (soft soil over bedrock). Results consistently shows detailed finite element model, best representing SSI, predicts higher damage probabilities at lower peak ground accelerations compared to the fixed-base and sway-rocking models. This suggests simpler models underestimate seismic vul-nerability. The significance of SSI, further examined by varying topsoil properties, underscores its critical role. The methodology developed, including the semi-automated analysis process using programming languages, provides a robust framework for conducting large-scale seismic fragility assessments. Ultimately, demonstrating SSI's crucial influence calls for reevaluating current seis-mic design practices and risk methodologies for more realistic building performance predictions.
