SEMI-ACTIVE SEISMIC CONTROL OF MID-RISE STRUCTURES USING MAGNETO-RHEOLOGICAL DAMPERS AND TWO PROPOSED IMPROVING MECHANISMS

Abstract

This research examines performance of semi-active control of structures usingMagneto-Rheological (MR) dampers. Mechanical specifications of this smart fluid damper changeby falling into the magnetic field, so by increasing intensity of magnetic field the resulting damperpower consequently increases. In this paper, two models of 9 and 20-story buildings were firstselected as case studies and respective specifications of these structures (mass, stiffness anddamping matrices) were calculated using valid sources as well as analysis of structures ignoringaxial deformations against imposed loads. Then, sample structures were simulated in a Simulinkenvironment. Consequently, optimum force determination processor, control system and MRdamper were modeled in Simulink environment and were installed on a structural system. Finally,the obtained results from damper equipped structure were compared with non-controlled structure.In semi-active control case, clipped optimal algorithm was considered as control algorithm andoptimal classic linear control method was used to determine control power. Based on the obtainedresults, it is observed that using this control method will significantly decrease structure response,such that MR damper can be about 12% to 36% effective in reducing maximum lateral drift and upto 21% in reducing maximum acceleration. Two mechanisms are eventually offered to improve thefunction of dampers and their performance. The proposed mechanism is shown to be effective inreducing the capacity and number of dampers required.