Semi-active Control Of The Asymmetric Civil Structures With MRD

Both theoretical analysis and seismic disasters indicate that the torsional response can aggravate destroying of the eccentric structures. So the control of eccentric structures under earthquake is an important issue in seismic response control. Magnetorheological damper (MRD) is a kind of intelligent and the most effective semi-active control device, and it is hot to research the control of structure using MRD. There are a large mount of researches on MRD and its application up to now, and many significant developments have been gained. However, there are many problems required to be further investigated including developing new type MRD, semi-active control strategy, torsional response control of eccentric structure using MRD, etc. The thesis focus on the vibration control of eccentric structures using MRD, and the main effects are devoted to the following aspects:(1) The double sigmoid model of MRD is proposed. A new mechanical model — double sigmoid model is developed based on the experimental study of MRD. The outstanding feature of the proposed model is a fact that both the magnitude of control current and a wide range of excitation conditions are under consideration. Through this model, the identification of parameters is relatively easy and the physical concept of the model is clear. Under different excitation conditions and control current, the comparison between the results given by this model and the experimental data shows that via the proposed model, the phenomena of the hysteresis nonlinear properties in higher velocity region and the saturation characteristic in lower velocity region of MRD can be described accurately.(2) The modified clipped-optimal control strategy (MCO) and the multi-state control strategy (MSC) are developed. According to the problems of amplification of local acceleration response appearing in the bi-state control method and the stiffness confirmed difficulty for the tri-state control method, two semi-active control strategies are proposed, the modified clipped-optimal control strategy which adjusts current continuously and the multi-state control strategy which uses the velocity response as state-switch parameter. The value of state-switch parameter in the multi-state control strategy is optimized by genetic algorithm (GA) method, and a formula is proposed. The simulation results indicate that the proposed two kinds of semi-active control strategies can avoid the amplification of local acceleration response, and they are simple, feasible and have a high application value.(3) The seismic response characteristics of the eccentric structures and the control effects of MRD are simulated. Based on the simplified method of finite element, the element stiffness...