Semi-active Control Strategy using Genetic Algorithm for Seismically Excited Structure Combined with MR Damper

Magnetorheological (MR) damper is a prominent semi-active control device for earthquake response mitigation of structures. The most important topic for the intelligent MR structures is choosing the control current of MR damper quickly and accurately. The typical control strategy is on-off control strategy, while inherent time-delay and coarse control precision lie in this strategy. This article proposes a semi-active control strategy for restricting the MR structures efficiently, in which the genetic algorithm (GA) is adopted to search for the optimal feedback control gain in time-delayed dynamic equations forming a GA controller, and next optimize the control current of the MR damper accurately by a series of GA procedure. The GA strategy has the capability to effectively control the MR structure involving time delay and adjusting for controlled current of the MR damper timely and accurately. Accordingly, numerical examples are used to testify that the feedback gain optimized by GA has the capability to reduce a given objective response dramatically. In addition, a comparison between GA controller and LQR controller indicates that the proposed approach performs much better than LQR method, especially in time-delay systems. Finally, simulation results for a seismically excited structure subjected by the MR damper are presented to verify that the semi-active strategy using GA is predominant in mitigating the dynamic structure efficiently. The strategy and the results presented will also throw light on the development and control of other novel structures.