Semi-Active Seismic Isolation System with Controllable Viscous Dampers Using Magneto-Rheological Fluid

Abstract

Many base-isolated buildings have been constructed using passive isolation systems to reduce response accelerations of superstructures due to earthquakes. The trade-off in the passive systems is that large relative displacements are inevitable to achieve satisfactory reduction in the response accelerations. To solve this trade-off problem, a semi-active seismic isolation system with a controllable viscous damper using a magneto-rheological fluid has been developed. The damping force of the MR damper can easily be changed by altering the magnetic field. However, the MR damper's response to the control signal is delayed, resulting in a negative effect on control performance. To improve this defect, a control law which takes the delay into considerations was proposed for the semi-active seismic isolation system. This paper outlines the results of simulation and excitation tests on the semi-active seismic isolation system with the MR damper using the control law.