عنوان مقاله [English]
In this paper, a new procedure is presented for active control of structures. This strategy is developed based on the structural dynamics topics so that well-known and fundamental structural dynamics theories are used to calculate the actuator force and determine the positions of assembling the sensor and actuator. The goal of such procedure is that the structural vibrations are damped in the shortest possible time. As a result, improving the efficiency of the control process is the most important goal of this study. For this purpose, the critical damping concept that is a fundamental structural dynamics theory is utilized to formulate the proposed active control scheme. Based on this concept, the structural vibrations are destroyed if system damping is in critical condition. In this case, there are no vibrations in the structural response and steady state response is achieved in the shortest possible time. In the conventional method, which has been previously developed for active structural control of dynamic systems, only the effect of first mode has been incorporated in the formulation. This approach i.e. only considering the effect of the first vibration mode decreases the efficiency of such techniques. As a result, the proposed method tries to overcome this defect by considering and including the effects of two vibration modes i.e. the first and second modes for determining the actuator force. Although there is only one actuator in the proposed method, this strategy improves the efficiency of the critical damping technique. Moreover, based on the condition of semi positive definiteness of total damping matrix corresponding to the dynamical system, a novel approach for determining the actuator and sensor location is suggested. According to the proposed theories, a new active control algorithm is obtained. Efficiency of the proposed method is assessed by active control of some shear buildings subjected to various loading conditions. Results demonstrate considerable merit of the proposed active control algorithm compared to the critical damping method.