Semi-active fuzzy control for seismic response reduction of building frames using variable orifice dampers subjected to near-fault earthquakes

In this paper, a fuzzy-rule-based semi-active control of building frames using semi-active variable orifice dampers (VODs) is presented. Additionally, the consequences of well-known characteristics of near-fault ground motions, forward directivity and fling step, on the seismic response control is investigated. The membership functions and fuzzy rules of the fuzzy controller were optimized by genetic algorithm. To illustrate the efficiency of the proposed fuzzy controller strategy in application and effects of near-fault ground motions, numerical simulation for a 10-story building frame equipped with VODs is presented. The VODs are installed in all storeys to prevent damage to the structure from severe earthquakes. The controlled response of the frame was compared with results obtained by controlling the frame by the classical clipped-optimal control method based on linear quadratic regulator theory. Results revealed that the fuzzy logic controller is capable of improving the structural responses and VODs are promising for reducing seismic responses during near-fault earthquakes.