Multi-Directional Base Isolation System for Coupled Horizontal and Vertical Seismic Excitations

Abstract

The concept of a new Multi-Directional Seismic Isolation (MDSI) system is developed to enhance the seismic performance of structures under coupled horizontal-vertical excitations. The MDSI system consists of a typical isolation unit and a Super-High-Damping-Rubber (SHDR) device to tune vertical stiffness without affecting horizontal movements. The efficiency of the proposed system is demonstrated for 3-, 5-, 8- and 12-story steel frames under 10 different combined vertical-horizontal earthquake excitations. Compared to conventional base isolation systems, MDSI can reduce the maximum vertical and horizontal accelerations by up to 55% and 25%, respectively, resulting in a significant reduction of non-structural damage due to acceleration.