Semi-active Control of Structures with MR Damper Using Modified Newmark Method Based on Instantaneous Optimal Control Algorithm

Magnetorheological (MR) fluid damper shows great promising in semi-active control of civil engineering structures, in which, fault-safe, low-power consumption, force controllability and rapid response are its advantageous. However, a major drawback that hinders its application rests with the non-linear force/displacement and hysteretic force/velocity characteristics. With regard to building control, it is crucial that a tractable model of the MR damper should be available before any design in realizable controller. There are several MR damper models proposed in the literature using a range of techniques. Models obtained by a deterministic approach include Bingham, phenomenological, Bouc-Wen models. The Bingham model cannot represents nonlinear behavior of MR damper and may be considered as a simple model for the hysteresis characteristic. The Bouc-Wen model uses a differential equation to depict the non-linear hysteresis with moderate complexity and is widely applied in building controls [1]. Nonlinear dependent relation between damper control force, floors displacement and velocity does not allow to solve governing equation of motion which makes the structure response analyzing impossible. There are a few new methods for estimating the response of structure with MR damper. In the present study modified Newmark-Beta method base on the instantaneous optimal control algorithm is used to estimate the response of the coupled system with MR damper, for the first time.