Seismic target drifts for underground railway stations. Cases of traditional rigid connections and sliding interior columns

Abstract

In this study, the seismic performances of underground structures with either transverse traditional rigid layout or sliding interior columns are numerically evaluated by pushover analyses; both the horizontal and vertical components of the seismic ground motion are taken into account. Thirty-one representative actual subway stations featured with various structural forms, soil types, and burial depths are analyzed in this study; although each of these stations has rigid connections between all their structural members, alternative solutions with sliding interior columns are also designed. The seismic performance of each station (with rigid connections and sliding columns) is evaluated in the framework of the Performance-Based Design by considering four Target Drifts: Normal Operational, Immediate Operational, Reparable Operational, and Irreparable. The corresponding drift thresholds are determined for each station, and then global average values for the two considered cases (traditional rigid layout and sliding columns) are proposed. The rationality of the proposed seismic performance quantification system is verified by comparison with observed damage (Daikai station, traditional rigid solution) and experimental results (shaking table test of reduced scale station model with sliding columns).