عنوان مقاله [English]
Nowadays, semi-active control systems are used extensively because of their stability in structural response and high ability in control. Semi-active control, by use of variable friction dampers, in order to improve the loss of the energy characteristics of passive friction dampers, has received more attention in recent years. Seismic vibration can produce high acceleration and displacement and, finally, result in damage to vulnerable equipment. Semi-active control systems with a frictional controller and extremely small force, and by means of limiting input acceleration and device displacement, can truly control the response of the above equipment.In this paper, the evaluation of the workability of a semi-active control technique, by means of variable friction dampers, to reduce the seismic response of equipment, and the effect of $H_infty$ control algorithms in systems accompanied by frictional controllers, is studied. This study demonstrates that the use of variable friction dampers with an adaptive property against various earthquake vibrations, and the requirement of low source energy, while, effectively, causing a decrease in the response of input acceleration to equipment, hold the device displacement to the floor with the least value. Results of this study, denoted by the use of frictional controllers and appropriate control algorithms that consider the effect of external disturbances and excitations, can help effectively to increase system ability to control equipment response.