SEISMIC RESPONSE CONTROL OF A BUILDING USING MR DAMPER WITH OPTIMAL STATIC OUTPUT FEEDBACK

Control of seismic response of a ten storey building fitted with magnetorheological (MR) damper is considered. Control force desired from the MR damper is obtained using Optimal Static Output Feedback (OSOF) control. Damper dynamics is modeled using modified Bouc-Wen element. This exhibits a non-linear relationship between damper force and input-voltage/states, making it difficult to obtain the input voltage required to realize a desired control force. Hence, two control voltage laws based on the MR constraint filter, i.e., Inverse Quadratic Voltage Law (IQVL) and Inverse On-Off Voltage Law (IOOVL), are proposed as an alternative to exactly predicting the force-voltage inverse dynamics. Maximum values of peak and RMS response quantities (Interstorey Drift, Displacement, Acceleration) are obtained for controlled building response using OSOF control with IQVL, IOOVL and an existing Clipped Voltage Law (CVL). These are compared with Linear Quadratic Guassion (LQG) control using the three voltage laws and with passive-on control using constant (saturation) voltage. A reduction in maximum peak and RMS values of interstorey drift and displacement is obtained when using OSOF control as compared to passive-on/LQG control. This is not uniformly true for maximum peak accelerations vis-a-vis passive-on control. Parametric studies regarding sensor configuration (i.e., type of output measured, placement and number of sensors), state weighting matrix Q (pertaining to displacement-, interstorey drift-, acceleration- based performance index), and control input weighting matrix R, are performed in order to obtain the most effective controller.