In this paper, a semi-active control method for seismically excited nonlinear benchmark buildings equipped with the controllable fluid viscous dampers is presented and evaluated. A fuzzy logic controller (FLC) is designed to alter the damping coefficient of controllable viscous dampers during the earthquake. A genetic algorithm (GA) is employed to find optimum fuzzy controller rules as well as adjusting the membership functions to minimize the overall damage index. This combination of genetic algorithm and fuzzy logic controller (GFLC) is also used to minimize the peak value of top story displacement response in order to verify the effectiveness of minimizing displacement on damage index. The effectiveness of the FLC is verified and illustrated using simulated response of a 3-story and a 20-story full-scale nonlinear benchmark building excited by several historical earthquake records through the computer simulation on MATLAB. A linear quadratic Gaussian (LQG) is designed as comparative active controller to minimize the peak values of top story displacement response. Moreover, for comparison, the results of a study that has used the self-organizing fuzzy logic controllers (SOFLC) with active actuators are used. The results demonstrate that the GFLC is quite effective in overall damage reduction for wide range of motions, compared with the SOFLC and LQG controllers.

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