EACS 2016 paper - Seismic test of building floor isolation using polynomial friction pendulum isolators

<div>EACS 2016 Paper No. 143</div><div><br></div>Compared to structural base isolation, floor isolation is a more cost-effective and efficient means for seismic protection of vibration-sensitive equipment in a building structure. However, in order to protect the precision equipment, floor isolation usually has to satisfy more stringent isolation performance than that of base isolation; at the meantime, it also calls for less isolation displacement demand due to the indoor space limitation. In order to satisfy these multiple demands, in this study, a multi-functional floor isolation system (FIS) that consists of several variable-stiffness sliding isolators, called polynomial friction pendulum isolators (PFPIs), is proposed and studied. Due to its variable-stiffness nature, the proposed system is able to achieve the desired dual performance objectives that were selected during the design stage for two-level seismic loads. The variable-stiffness hysteretic property of the proposed system was verified by a shaking table test conducted on a prototype PFPI-FIS. Moreover, by using the parameters of the prototype system, the seismic performance of the prototype PFPI-FIS under ten ground motions, which represent earthquakes with different spectral contents and intensity levels, are investigated numerically. The simulated results demonstrate that the isolation performance of the PFPI-FIS does comply with the designated dual performance objectives, which yield either acceleration or displacement control depending on the earthquake intensity and isolator drift.