Seismic fragility analysis for subway station considering the soil non-linear dynamic property uncertainty

Abstract

The dynamic characteristics of a site play a crucial role in the seismic response of underground structures. However, existing seismic vulnerability models often inadequately account for variability in soil parameters. This paper examines a frame subway station underground structure, performing both a traditional seismic vulnerability analysis considering only seismic motion record uncertainty, and a comprehensive analysis incorporating uncertainties in soil dynamic parameters. These parameters include soil shear wave velocity and three additional parameters reflecting the soil’s nonlinear dynamic behavior. The Incremental Dynamic Analysis (IDA) method was used to develop both the traditional seismic fragility curves and the curves incorporating these additional uncertainties. Differences between these two curves were quantified and compared using the Wasserstein distance. The results indicate that ignoring soil dynamic parameter uncertainty significantly impacts the assessment of post-earthquake failure probability for underground structures. This impact varies with seismic motion intensity, and the discrepancy between the two seismic fragility curves increases as the performance level of the assessed structure rises.