Optimal Design of Active Multiple Tuned Mass Dampers (AMTMDs) For Nonlinear Hysteretic Structures

In this paper optimal design and effectiveness assessment of active multiple tuned mass dampers (AMTMDs) in reducing the vibration of nonlinear hysteretic structures has been studied. For active control of nonlinear structures the Newmark-based instantaneous optimal control algorithm has been used. Optimal parameters of AMTMDs and weighting matrices of active control performance index have been determined based on minimization of the maximum required control force of ATMDs to below the maximum drift of structure to a specified limit. For solving the optimization problem which includes a large number of variables, genetic algorithm (GA) has been applied. For numerical simulation, an eight–storey shear frame with bilinear hysteretic behavior subjected to white noise excitation and for different values of MTMDs mass ratio and ATMDs number, optimal AMTMDs have been designed. Also the efficiency of the AMTMDs mechanism under both near-fault and far-fault earthquakes has been tested. The results of numerical simulations show the effectiveness of the proposed method in designing AMTMDs on nonlinear structures. Also, it has been concluded that using AMTMDs could be effective in mitigating the damage of nonlinear structures which the amount of reduction depends on the input earthquake characteristics, AMTMDs mass ratio and ATMDs number.