Optimal semi-active control of seismically excited MR-equipped nonlinear buildings using FLC and multi-objective NSGAII algorithms considering ground excitations

Among the variety of control algorithms, fuzzy logic control (FLC) strategies have the advantage of not depending on the system model behavior, of being simple, and intrinsically robust, and therefore they have recently been used to control the dynamic response of multi-story buildings equipped with semi-active supplemental damping devices. However, their tuning has shown to be a difficult task, especially when they use a multi-objective strategy. Introducing several FLC-based control strategies, an optimal semi-active control strategy using an advanced multi-objective optimization procedure called Non-dominated Sorting Genetic Algorithm II (NSGAII) has been proposed in this paper to mitigate the nonlinear structural response of a new generation of benchmark buildings. Besides peak inter-story drift ratio and peak floor acceleration, the base shear force as an extra objective has been used as the three-objective function for the multi-objective optimal design problem. The robustness of the optimized semi-active algorithms which were produced using binary tournament-based parents has been assessed for 3-story and 20-story nonlinear benchmark buildings experiencing nonlinear behavior during a wide range of earthquake records. The results showed that the performance of optimized semi-active control systems is acceptable and in some cases work much better than the non-optimized controllers taken in previous studies.