Shaking table tests on semi-active base-isolation system by magnetorheological fluid damper

Recent study is to the performance of variable dampers for reducing earthquake response of buildings or wind induced sway. The variable damper using magnetorheological fluid (MR damper) changes its damping force by changing the magnetic field acting on the MR fluid according to an electric current. MR dampers have a simple mechanism and don’t need a large amount of energy. Semi-active control using such a variable damper stabilizes building responses in an earthquake better than the conventional passive control. Basic characteristics of the MR damper have been clarified. This time, authors proposed control algorithm of base-isolated structure, which carried out semi-active control by optimal regulator theory. This control algorithm reduces response displacement and response acceleration for the purpose of, and aims at enhancements, such as safety and amenity. This paper presents a comprehensive study on the performance of the MR damper to base-isolated structure. It's describes shaking table tests on a three-story large-scale test frame with base-isolated structure. The test results verify the controlling system and the control effect as a semi-active device of the MR damper.