Comparative performance of seismic mitigation devices for underground subway station

Abstract

Reducing horizontal deformation of vertical support columns is effective in improving structural seismic resilience and performance of shallow buried underground frame structures. This paper investigates the seismic response of underground station mitigation devices with laminated rubber bearings (LRB) and arc groove roller bearings (AGRB) installed at the column ends based on this seismic mitigation design concept. The performance of different seismic mitigation devices is evaluated and compared considering different earthquake combination conditions and intensity levels as well as key parameters of bearing characteristics. The results demonstrate that both bearing types are effective in mitigating the seismic damage of station structure by significantly reducing the internal forces of structural members and their deformation response, especially the damage of the central column. However, the AGRB is better than that of LRB under medium and large earthquakes. Within the practical range of design parameters, the seismic mitigation rate of LRB exceeds over 60 %, while the seismic mitigation rate of AGRB exceeds 80 %. In addition, as the peak ground acceleration (PGA) increases, the effectiveness of LRB seismic mitigation decreases while the effectiveness of AGRB increases slightly. It is found that the seismic mitigation rate of the central column increases with the increases in horizontal stiffness of the LRB and the decrease in friction coefficient of the AGRB. These findings inform the reliable design of seismic mitigation devices for underground subway station structures.