A SEMI ACTIVE CONTROL STRATEGY FORSEISMIC TORSIONALLY COUPLEDBUILDING STRUCTURES

This paper addresses the effects of different semi-active control strategies on seismic responses of onestory,asymmetric-plan systems. The Magneto-Rheological (MR) dampers have been used as a semi-active control device in numerous researches both for symmetric and asymmetric buildings due to their attractive characteristics. However, one can show that the level of reduction in seismic torsional responses of asymmetric buildings is strongly affected by the plan asymmetric parameters of the building. To examine the effect of asymmetry on the dynamic behavior of a controlled typical structure, a parametric study is performed using a mathematical model of a one-story building with an asymmetric stiffness distribution in one direction. The model is subjected to a uniaxial lateral disturbance, exciting both lateral and torsional motions. Due to the highly nonlinear dynamic behavior of MR dampers, existing uncertainty of seismic excitation and also torsional behavior of the systems, development of a robustness control algorithm is found as a significant challenge. Therefore application of optimal strategy to create an admissible control algorithm and attain the desired level of performance is also investigated in this study. In order to evaluate the effectiveness of the proposed methods, the performances of semi-active controllers are compared with some other control algorithms in a numerical example.