Investigation of Structural Response Of Magneto Rheological Elastomer (MRE) Based Multi Degree Of Freedom (MDOF) Isolated Structure Under Sinusoidal and Earthquake Excitations

Abstract

Fixed base structures subjected to earthquake forces are prone to problems like attraction of greater forces to structure, amplified accelerations to non-structural components, expensive design for better seismic performance etc. Base isolation applied at foundation of the vulnerable structures is a radical bypass from the conventional approaches utilized by structural engineers. But practical implementation of Passive Base Isolation is constrained by factors like large displacements at isolation level, uplifting forces at isolators and vulnerability to unpredictable and versatile earthquakes. This study is focused on the development of MRE based adaptive seismic isolator and evaluation of smart base isolation system under various harmonic and earthquake loadings. The proposed system employs a magneto-rheological elastomer (MRE) based adaptive isolation layer under the building structure. The building is idealized as 5 degree-of-freedom (DOF) structure with the mass lumped at each storey. The stiffness of MRE isolation layer is adjusted using Linear Quadratic Regulator (LQR) optimal feedback control algorithm. A total of 36 simulations have been performed for fixed base, passively isolated and MRE based isolated structures under various harmonic and earthquake loadings for analyzing a total of 612 responses of the structures. The simulation results show that MRE based isolation has significantly reduced all the responses compared to passively isolated structure for most of the earthquake loadings. For harmonic loading however, the passively isolated structure outperformed the MRE isolated structure in terms of storey drift and acceleration responses.