Seismic vulnerability analysis for shallow-buried underground frame structure considering 18 existing subway stations

Abstract

The variability of structural engineering parameters is not accounted for in available literature on seismic vulnerability of underground frame structures. This study investigates the seismic vulnerability of 18 existing subway stations with different site condition, structural stiffness, reinforcement ratio and buried depth employing two-dimensional (2D) finite element analysis considering soil-structure interaction. The peaks of structure inter-story drift ratio under different earthquake intensity of different ground motion records are obtained from non-linear dynamic time-history analysis. Taking the inter-story drift ratio as the damage measure (DM) and the peak ground acceleration (PGA) as the ground motion intensity measure (IM), the seismic vulnerability curves of 18 subway stations are constructed. The comparison of seismic fragility curves of different subway stations demonstrates that site conditions are critical to the post-earthquake structure probability of failure. Furthermore, representative seismic fragility curves are established based on the data collected form the computed results of 18 subway stations, which can aid in evaluating the seismic performance of existing urban underground frame structures in China. The results of this study can provide reference for the performance-based seismic design of urban underground frame structures.