EXPERIMENTAL STUDY ON MITIGATION OF SEISMIC RESPONSE OF A BUILDING BY VARIABLE DAMPERS

Abstract: In this study, the damping force algorithm called the viscous-plus-variable-friction damping force algorithm is proposed by combining advantageous features of typical viscous and friction dampers. The variable damper with the proposed algorithm can be represented by a viscous element placed in series with a variable-friction element. As a piston velocity increases from zero, the damping force is generated by the viscous element. This is aimed to allow energy dissipation at a small velocity. When the damping force reaches a peak value of the viscous element or a preset force limit, the sliding of the variable-friction element occurs, resulting in a constant damping force. A variable damper with the proposed damping force algorithm was developed using a magnetorheological (MR) damper. A series of cyclic loading tests of a MR damper was conducted to develop the mathematical model of the MR damper for control purpose. It is found that the proposed algorithm can be realized by the MR damper with a good accuracy. Subsequently, the MR damper was installed in the first story of a three-story steel model building. The model building is excited by a shaking table under a one-directional ground motion. It is found that the proposed damping force algorithm is effective in controlling the displacement, acceleration, and column displacement of the model building