A vertical isolator with high horizontal resistance for layered isolation of large hub buildings

Abstract

A layered isolation system is proposed for large hub buildings by installing horizontal isolators at the base of the substructure and vertical isolators at the supports of the long-span spatial structure separately. Significant horizontal static forces which can be close to the gravity loads of the spatial structure are normally generated on the vertical isolators, which will seriously affect the vertical isolation effect. In this paper, a vertical isolator with high horizontal resistance is developed for the layered isolation system of large hub buildings. The developed isolator is composed of a horizontal-force-resisting component and a vertical-isolation component. The horizontal-force-resisting component is designed to resist horizontal forces from the spatial structure and restrain the horizontal displacement of the isolator. The vertical-isolation component is designed to support vertical loads of the spatial structure and isolate vertical seismic excitations. A series of vertical sinusoidal motion tests and numerical simulations are carried out to investigate the vertical hysteretic behavior of the isolator considering horizontal forces. The maximum horizontal force is as large as the designed gravity load on the isolator. Results show that the vertical hysteretic behavior has typical friction characteristic and it is influenced by the loading conditions, the geometric parameters of the horizontal-force-resisting component and the friction coefficient of the pin connections. Additionally, a theoretical model of the vertical restoring force of the isolator is derived and validated, and the vertical isolation performance is analyzed based on the model. The vertical seismic responses of the long-span spatial structure can be reduced by up to 60%–80%. The developed isolator is proved to be an efficient solution for vertical isolation considering large horizontal forces.