Abstract: This research focuses on the optimization of fuzzy control algorithm for seismic control of asymmetric reinforced concrete structures equipped with magnetorheological (MR) dampers and flexible foundations, taking into account the nonlinear behavior of structures. To investigate various parameters of structures with torsional behavior, 27 parametric asymmetric structures with different eccentricity, period and different ratios of torsional frequency to translational frequency have been generated, in which their eccentricity is of the inertial type. The load-bearing system of the structures is considered as a special reinforced concrete frame, and nonlinear behavior is assigned to the mentioned structures using fiber elements in columns and concentrated plastic hinges in beams. Then, each of these structures is equipped with magnetorheological (MR) dampers, for which the model considered for this damper is a simplified Bouc-Wen model. In order to control the MR dampers, a fuzzy logic system has been used, and the parameters of this fuzzy system have been optimized using the multi-objective elite Non-dominated Sorting Genetic Algorithm II (NSGA II). In this algorithm, minimizing the displacement and acceleration values of the soft edge simultaneously is considered as the goal of the multi-objective optimization algorithm. The design of this control algorithm has been carried out using the Northridge acceleration record, and to eva‎luate the robustness of the controller against input uncertainty, 4 near-fault records and 3 far-fault records have been eva‎luated. In order to further eva‎luate the controller, the effect of foundation flexibility on structures equipped with the optimal fuzzy controller has also been investigated. In order to simplify the analysis of the results, the results are presented in a relative form. The results demonstrate the significant success of the optimized fuzzy control algorithm in reducing structural responses, including displacement, velocity, and center of mass. Furthermore, the controlled shear force of the structure shows a significant reduction compared to the uncontrolled structure. Other indicators such as MR sensor voltage and the ratio of applied force to the total weight of the structure are reported in eva‎luating the performance of the MR sensor, all of which demonstrate the ability of the designed algorithm to control seismic responses of structures under severe earthquakes. The eva‎luation of the resistance of the control algorithm against input uncertainty shows the success of this algorithm in controlling torsionally asymmetric structures under different earthquake excitations with different frequency contents. The behavior of the uncontrolled and controlled structures was examined, and it was found that while the behavior of most controlled structures remains linear, depending on the transfer mass, the controlled structure can also enter its nonlinear behavior zone. Nevertheless, the optimized fuzzy algorithm is capable of controlling it. Furthermore, taking into account the soil-structure interaction effect leads to more successful control algorithm.

اميرمهدي حلبيان

فرهاد بهنام فر , علي بخشي