In situ tests of building structures isolated by innovative three-dimensional vibration isolation bearings

An innovative three-dimensional vibration isolation bearing (3D-VIB) was proposed in past studies to mitigate rail-induced vibration and improve the seismic performance of buildings. The 3D-VIB was composed of a thick laminated rubber bearing as the vertical vibration isolation element and a friction pendulum system as the horizontal seismic isolation element. In this study, in situ tests were carried out on a subway over-track structure with 3D-VIBs. The in situ tests included the subway-induced vibration excitation test and the horizontal loading test on the same structure. In the subway-induced vibration excitation test, the vertical isolation performance of the test structure was changed by transforming the isolation layer from a normal vibration-isolation-state to a non-isolation-state. The comparison between the two states proved that the installation of 3D-VIBs significantly changed the vertical vibration mode and reduced the subway-induced vibration of the superstructure. The shear performances of the isolated structure were examined by the horizontal loading test, which subjected the superstructure to a large horizontal movement under external load. The shear performances of the structure with 3D-VIBs were consistent with that of the 3D-VIB specimens measured in the laboratory. The in situ tests confirmed the effectiveness and stability of the 3D-VIBs when applied to practical engineering.