Application Of MR Damper In Structure Dynamic Control

Magnetorheological (MR) fluids belong to the class of controllable fluids. The essential characteristic of MR fluids is their ability to reversibly change from free-flowing, linear viscous liquids to semi-solids having controllable yield strength in milliseconds when exposed to a magnetic field. This feature provides simple, quiet, rapid response interfaces between electronic controls and mechanical systems. MR dampers are one of the most promising control devices for civil engineering applications to earthquake hazard mitigation, because they have many advantages such as small power requirement, reliability, and low price to manufacture. Recent work by several researchers has indicated that MR dampers, when appropriately implemented, achieve significantly better results than passive control systems; in fact, they may even outperform fully active control systems, demonstrating significant potential for controlling structural responses to a wide variety of dynamic loading conditions.In this paper, the major aim is establishing analysis design method about magnetorheological structure. The following work is done:(1) To develop control algorithms that take maximum advantage of the unique features of the damper and to evaluate its effectiveness for structural control applications, a model that can adequately characterize the damper's intrinsic nonlinear behavior must be used. Following a description of the MR damper, a review of several idealized mechanical models for fluid damper is presented and finally a Phenomenological Model for Magnetorheological Dampers is used.(2) MR dampers, like most semi-active control devices, are intrinsically nonlinear, making it challenging to develop control strategies that can optimally exploit their unique features. Because of stochastic nature of earthquake ground motions and because of their successful application in previous studies, the H₂/LQG strategies are used and deduced in detail.(3) Based on the already existed Semi-Active control algorithm of Clipped Optimal Control (COC) algorithm and smart passive control, combine their virtue, a mixed algorithm was proposed and shown to be effective for civil engineering applications through numerical simulation.(4) Using numerical simulation, and using the three control algorithms of COC, smart passive control and mixed control, three-story, six story and twelve-story structures were controlled. The results showed that mixed control can effective control both acceleration and displacement.