Numerical Assessment of Bidirectional Roller Bearing Isolators under Near-Fault Earthquakes

Abstract

In this research, a bidirectional seismic isolation device composed of sloped bearing plates and multiple rollers arranged in both orthogonal-in-plane directions is numerically studied. A previous analytical model of a single direction of roller bearing (RB) system is extended to a two-direction RB system. Several experimental tests in a physical building model with and without an RB system are used to validate the numerical model. The model is used to perform the nonlinear response of a four-story multi-column building when subjected to pairs of scaled near-fault earthquake records. The effect of the inclination angle of bearing plates in the range of 1.0° to 4.0°, the sliding friction force, and supplementary damping mechanisms ranging from 0.0 to 0.5 N/kg (i.e. friction force normalized with the structure mass) are also investigated. The results show that the proposed bidirectional RB system is suitable for reducing the seismic response of stiff and flexible multi-column structures. In particular, the RB system reduces the acceleration responses by 5% to 85% in flexible structures and 86% to 96% in stiff structures. Furthermore, bearing plates with an inclination angle greater than or equal to 3.0° have significant benefits in terms of self-centering capacity.