Characteristics and Modeling of Multiple Direction Optimized-Friction Pendulum System With Numerous Sliding Interfaces Subjected to Multidirectional Excitations

In this paper, a base isolator called a multiple direction optimized-friction pendulum system (Multiple DO-FPS) with numerous sliding interfaces is proposed. To understand the mechanical behavior of the Multiple DO-FPS isolator under multidirectional excitations, an analytical model called the multiple yield and bounding surfaces model is proposed. On the basis of the derived mathematical formulations for simulation of the characteristics of the Multiple DO-FPS isolation bearing, it is revealed that the natural period and damping effect of the Multiple DO-FPS isolator are a function of the sliding displacement and sliding direction. By virtue of the proposed model, the phenomena of the sliding motions of the Multiple DO-FPS isolator with numerous sliding interfaces subjected to multidirectional excitations can be understood in a simple manner. The analytical results indicate that the natural frequency and damping effect of the Multiple DO-FPS isolator with numerous concave sliding interfaces change continually during earthquakes and are controllable through appropriate designs.