Full‐Scale Shaking Table Tests on a Four‐Story Frame Structure With Multi‐Dimensional Earthquake Isolation and Mitigation Devices

ABSTRACT Due to the rocking effect, the majority of existing three‐dimensional (3D) seismic isolators are applied to low‐rise structures, and there are few studies conducted to investigate the seismic response of 3D base isolation structures (3D‐BISs) featuring large aspect ratios. This study proposed a novel multi‐dimensional earthquake isolation and mitigation device (denoted MEIMD), which was composed of a viscoelastic (VE) bearing, disc spring‐damper elements (DSDEs), and rocking suppression elements (RSEs). Dynamic tests were conducted to reveal the mechanical property of the MEIMD under different excitation frequencies and displacement amplitudes. Then, to explore the seismic performance of the MEIMD and the rocking effect of the 3D‐BIS, full‐scale shaking table tests were implemented on a four‐story frame structure under one‐dimensional (1D) and 3D ground motion excitations. The results demonstrate that, compared to the fixed‐base structure, employing the MEIMD significantly reduced the horizontal accelerations, and this isolation effect primarily stemmed from a coupled horizontal‐rocking motion mode. The MEIMD ensured a nearly vertical translational motion mode for the superstructure, thereby effectively mitigating the out‐of‐plane vibrations of floor slabs. Compared to that under 1D excitations, the overall isolation effect of the MEIMD was weakened under 3D excitations, which was ascribed to the aggravated coupling between horizontal and vertical motions of the seismic isolation interface. Finally, a simplified analytical model is established for the 3D‐BIS, and good agreement is found between analytical solutions and test results.