Characterization and Modeling of the In-Plane Multi-directional Behavior of a Rolling Pendulum Isolation System

Abstract

The social and economic losses caused by an earthquake can be mitigated by using a rolling pendulum (RP) isolation system to protect vital non-structural building contents. In this paper, a physics-based mathematical model for an RP bearing—as well as an isolation systems comprised of these bearings—is derived. An experimental campaign for multi-directional characterization of RP isolators was conducted. A single, full-scale (four RP bearings) isolation system was tested. These tests were performed using an in-plane multi-directional shake table. Restoring forces and moments were measured by restraining the top of the isolation system from moving horizontally by using three struts with uniaxial load cells. Controlled-displacement characterization tests were defined to capture the envelope performance of the isolation system subjected to a variety of multi-directional conditions, by specifying combinations of slow and fast tests, various in-plane ($X$, $Y$, and $\theta$) amplitudes and frequencies, and different orbits. The experimental results were used to calibrate and validate the mathematical model.