Shaking Table Tests of a Layered Isolation System with High-Horizontal-Resistance Vertical Isolators for Large Hub Buildings

Abstract

To mitigate the horizontal seismic responses of the substructure and the 3D seismic responses of the long-span spatial roof structure in a large hub building, an innovative layered isolation system has been proposed. This system entails the installation of traditional horizontal isolators at the base of the substructure and high-horizontal-resistance vertical isolators at the supports of the roof structure. To verify the system’s isolation performance, a series of shaking table tests of a 1/12-length-scaled simplified model with a latticed shell as the roof structure and concrete frames as the substructure were carried out using friction pendulum bearings and recently proposed vertical isolators. Four distinct model configurations, including the nonisolated, vertically isolated, horizontally isolated, and layered isolated scenarios, were tested. The asynchronous behavior of the vertical isolators in the layered-isolated model is investigated. The results show that the layered isolation is as effective as the horizontal isolation in reducing the seismic responses of the substructure and the seismic responses of the roof structure induced by the horizontal ground motions. It is also as effective as the vertical isolation in reducing the seismic responses of the roof structure induced by the vertical ground motions and generally provides 30% higher isolation ratios than the horizontal isolation for the seismic responses of the roof structure affected by horizontal and vertical ground motions. The horizontal seismic effect considering the frictional nature of the vertical isolators is found to mainly cause the asynchronous behavior of the vertical isolators in the layered-isolated model.