Seismic Vibration Control of Nonlinear Structures Using Semi-Active Tuned Mass Dampers

In this paper, designing semi-active tuned mass damper (SATMD) for reducing the response of nonlinear frame structures under earthquake excitations has been studied. The semi- active characteristic of the control system has been achieved by modifying the damping in each time step. To determine the appropriate command signals for selecting the damping coefficient of SATMD, a semi-active control algorithm based on nonlinear instantaneous optimal control and Clipped Optimal Control concept has been developed. Also for optimal design of the control system, the design parameters have been determined by solving an optimization problem that minimizes the maximum response of the structure using genetic algorithm (GA). As numerical example, for an eight-storey nonlinear shear frame with bilinear hysteresis behavior under white noise excitation, SATMD has been designed. The results of numerical simulations show the capability of the proposed method for determination of control signal as well as the effectiveness of the SATMD mechanism in reducing the response of the nonlinear structures under earthquake excitation. In addition, comparing the performance of SATMD with those of passive and active tuned mass dampers shows that SATMD has worked better than passive tuned mass damper while active mass damper shows better performance than SATMD .