Seismic performance analysis of a smart base-isolation system considering dynamics of MR elastomers

This article investigates a smart base-isolation system using magnetorheological (MR) elastomers, which are a new class of smart materials whose elastic modulus or stiffness can be adjusted depending on the magnitude of the applied magnetic field. The primary goals of this study are to develop a smart base-isolation model that represents the field-dependent dynamic behaviors of MR elastomers, to design and construct a scaled smart isolation system and a scaled building structure for a proof of concept study and to investigate the dynamic performance of the smart base-isolation in mitigating excessive vibrations of the scaled building structure under earthquake loadings. To this end, a dynamic model of an MR elastomer was first obtained based on characteristic test results of MR elastomers in shear mode. The dynamic model was then incorporated in a shear building model. Its effectiveness was validated by comparing the test results of a small-scale, single-story building structure coupled with the MR elastomer under harmonic excitations. After validating the MR elastomer-based base-isolation system, a further numerical study was performed to evaluate its effectiveness under seismic excitations. The results show that the proposed MR elastomer base-isolation system with the fuzzy logic control algorithm outperforms the conventional passive-type base isolation system in reducing the responses of the building structure for the seismic excitations considered in this study. The results further suggest that the feasibility of using MR elastomers as variable stiffness elements for enhancing the performance of conventional base-isolation systems.