Multiple-variable frequency pendulum isolator with high-performance materials

Abstract

The spherical surface of the friction pendulum system (FPS) inevitably introduce a constant dominant period, which may lead to resonance problem when subjected to the ground motions with long-period components. In this study, a multiple-variable frequency pendulum isolator (MVFPI) was developed to overcome this limitation. The sliding surface of the MVFPI was predefined as a continuous piecewise function to combine the seismic performance of MVFPI with different seismic intensities. The high-performance materials, polytetrafluoroethylene (PTFE) fabric and shape memory alloy (SMA) were utilized to improve its durability and control the deformation. Based on the underlying principles of operation, the force-displacement relationships of the MVFPI were derived. A series of tests of high-performance materials and MVFPI were conducted to verify the accuracy of the derived hysteresis model. Parametric studies and optimal analysis were carried out on the critical parameters of the MVFPI. The results indicate that the MVFPI has the desired hysteretic behavior as prescribed by the derived formulas. Moreover, the seismic responses of the structure isolated by MVFPI with optimal parameters could be controlled within the desired range.