Semi-Active Control of Floor Isolation System Using MR-Damper

Semi-Active Control of Floor Isolation System Using MR-Damper

This paper presents the performance evaluation of a semi-active controlled floor isolation system for earthquake effect reduction. The floor isolation system consists of a rolling pendulum system and a semi-active controlled magnetorheological(MR) damper. The modified Bouc-Wen model was used to represent the behavior of the MR damper. A series of performance tests of the MR damper was made and has been used for system identification. Two contrasting control methods including LQR with continuous-optimal control and Fuzzy Logic control were investigated experimentally as potential algorithms, and comparisons were made from the results. Unlike the clipped-optimal control, LQR with continuous-optimal control can output the continuous command voltage to control the MR damper, and obtain smoother control effect. A three-story steel structure with floor isolation system on its second floor was tested on the shake table. Scaled historical near and far-field seismic records were employed to examine the controller’s performance with respect to frequency content and peak ground acceleration(PGA) level. Experimental results show that both control algorithms can suppress the acceleration of the isolated floor during small and large PGA levels and alleviate both displacement and acceleration simultaneously in larger, near-field events. Both control algorithms were found adaptive and robust to various intensity of excitation. This investigation demonstrates the feasibility and capabilities of a smart semi-active controlled floor-isolation system.