A methodology to find the simultaneous size, geometry and topology design optimization of structures using Genetic Algorithms (GAs) is proposed. The methodology considers that the large structures are constructed from the duplication of some basic structures called bays. For realistic optimal designs, the cross-sectional areas are extracted from the standard profiles and the optimization process is performed considered the AISC design standards. Then a methodology to find the characteristic parameters of the Bouc-Wen model is presented. The methodology considers the effect of each individual term of the Bouc-Wen model over the hysteretic loop to estimate the appropriate values of the parameters. From the results, a new model based on the Bouc-Wen model is proposed with the current, frequency and amplitude excitation as variables. Based on this, a Finite Element Model (FEM) for the MR damper is developed and then integrated to the FEM model of the entire structure. Subsequently, a vibration suppression strategy using MR damper was proposed to improve performance index of the structure. Finally, the application of MR dampers as translational actuator is investigated.