Isolation mechanism of a subway station structure with flexible devices at column ends obtained in shaking-table tests

A series of shaking-table tests of a subway station structure with mini natural rubber bearings (Mini-NFtBs) installed at column ends were carried out for near-field earthquake motions. By comparing the dynamic response of the structure model with or without Mini-NRB, the isolation mechanism and effectiveness of Mini-NRB on the station model were studied. It is found that the Mini-NRB has an obvious isolation effect on the column of the structure. After installing Mini-NRB, the lateral stiffness of the column decreases greatly, which reduces the bending moment and shear force at the column end by 60%-80% and about 90% respectively under near-field earthquake excitation. The test data, real-time monitoring pictures, and ultimate structural seismic damage all show that Mini-NRB shares most of the lateral deformation of the column, so that the column is no longer a vulnerable spot of the subway station structure. In addition, Mini-NRB reduces the high frequency component of the middle plate response, thus reducing the peak acceleration response of the middle plate by 3%-10%. However, the lateral deformation of the structure and the internal force of the sidewall will increase. The lateral deformation of the structure with Mini-NRB increases by 30%-50% and the bending moment at the end of the side wall increases by 5%-25%.