STUDY ON THE ISOLATION EFFECT OF SUBWAY COVER STRUCTURES

In order to study the seismic isolation effect of the subway superstructure comprehensively, a simplified two-degree-of-freedom model of the large base with multiple towers was presented, and the influences of mass ratio and period ratio on dynamic characteristics and seismic response of structures were investigated. In addition, a precise model of the subway superstructure was established by ETABS to study the effect of tower height, tower number, isolation floor stiffness, and viscous dampers on the structural dynamic characteristics, seismic isolation coefficient. The analysis results of the simplified two-degree-of-freedom model show that in the general period ratio range, the shear-weight ratio of the tower has almost no change with its mass variation, while the shear-weight ratio of the large base decreases when the tower mass increases. The analysis results of the precise model of the large base with multi-tower show that the seismic inertial force is evenly distributed along the height of the tower, and the building height has little effect on the earthquake action, and the seismic effect of the large base increases slightly as the height of the tower increases. As the number of towers increases, the seismic isolation effect of the tower decreases slightly, the seismic effect of the large base is less than that of non-seismic isolation structures. As the stiffness of the seismic isolation floor increases, the seismic effect of the tower increases and the seismic effect of the large base decreases. After viscous dampers are installed, the distribution of seismic force along the height of the tower changes significantly, the seismic action decreases at the bottom of the tower and the seismic action is significantly amplified at the top. Setting viscous dampers can effectively reduce the seismic action of the large base.