Experiment-based performance evaluation framework for isolated structures in underground subway station–soil–aboveground structure interaction system under seismic excitations

Abstract

Owing to the complementary functions of aboveground and underground structures, the complex structure group has been practically applied in many real-world situations. For the aboveground structures, isolation technology is widely adopted as an efficient approach to improve their seismic performances. However, being limited to the isolation effectiveness and design of the single isolated structures, previous studies have ignored the inevitable influence of the underground structure–soil–aboveground structure interaction (USSI) on the aboveground structure. This study proposes a performance evaluation framework for the isolated structures facilitated by a sliding bearing that considers the USSI. A series of shaking table tests and numerical simulations are performed to establish a reference database of the proposed framework. The performance evaluation procedure is detailed for the USSI system, based on which the seismic performances are investigated for experimental and numerical models. Following the proposed framework, the influences of various soil conditions, sliding bearing parameters, and seismic excitations are systematically quantified, while emphasizing the necessity of the USSI in this study. The results show that the isolated structure in this case not only significantly improves the multiple seismic responses in terms of acceleration, displacement, and layer drift but also performs adequately in weakening the negative effect from the underground station. According to the parametric analysis results, the seismic performances of the isolated structure in the USSI system are extremely sensitive to the soil type, friction coefficient, spring stiffness, and input frequency, which can be generally incorporated into the proposed performance evaluation framework.