Semi-active Fuzzy Control of 5-Story Structure under Near & Far Field Earthquakes Using Piezoelectric Friction dampers

One of the main challenges civil engineers face today is to find more effective means for protecting structures and their contents from the damaging effects of dynamic hazards such as strong earthquakes. Vibration control of civil engineering structures have been studied for three decades. Casualties and economic damages in recent earthquakes at different countries show the importance of vibration control of structures. Vibration control of structures evolves from passive control, active control to semi-active control. Recently, semi-active control systems have attracted much attention because they have good efficiency with best features of both passive and active control. In this paper the performance of the semi-active control systems used by piezoelectric friction dampers was studied. The damper system was set on 5-story structure model and in order to adjust and assign the voltage on piezoelectric elements; the fuzzy logic controller was used. Two input variables including relative displacement and velocity of stories were assigned to the fuzzy logic controller; moreover, the command voltage was assigned as output variable. Incremental dynamic analysis of structure with maximum acceleration from 0.1g to 1g was used. The results of both semi-active and passive control were compared. The average results of semi-active control for displacement and base shear evaluation criteria show 12 and 3.4% of improvement compared to those of passive control, respectively; under farfield earthquakes while 13.8% and 4.7% improvements were observed under near-field earthquakes. Moreover, the sensitivity of the semi-active control systems shows 43% and 33.1% reduction compared to that of passive control under far-field and near-field earthquakes respectively.