Mitigate Seismic Response of Three-Span Bridge Using MR Damping System

In this paper, a mitigation of earthquake response is aimed at by constituting an MR damping system in a three-span bridge. It is a system where bridge spans are connected by means of an MR damper to control their vibration. A model structure of three-span bridge (12 m long) was built with an MR damper applied to connect each span, one between span A and B, the other between span B and C, and the MR damping system for this study was designed to work as a single unit with five components, that is, three spans and two MR dampers. Shaking table tests were carried out by inflicting a 40% load of Kobe earthquake to see how effective the system would be in mitigating seismic responses. All the tests were done under various conditions (un controlled, passive off, control algorithm) in order to closely examine and analyze under which condition mitigation could be maximized and how mitigation could be effected. As a result of the tests, it was found that the MR damping system was effective in reducing three spans from pounding each other and its active performance decreased the relative displacement of the bridge structure. Therefore, it was proven to be effective in attenuating the seismic responses of three-span bridge.