Semi-Active Control Research For The Vibration Of Stay-Cable By MR Damper

The stay cable is the main structure in force of cable-stayed bridges. Because of the characteristic of the relatively small mass and very low inherent damping, it's easy to cause vibration. The accurate analysis for the dynamics characteristic of stay cable is an important work for the design of cable-stayed bridge.The research of paper involves the following contents.1. The structural model of damper system on the stay cable is designed. Based on this model, the motion equation of MR damper- stay cable system is achieved. Then the mode analysis for the system is done by Ansys to achieve the preceding five steps'vibration frequencies of stay cable model. Meanwhile, through the analysis of transient state, the mass matrix, the rigidity matrix and the preceding five steps'mode vector of the stay cable- damper system are determined.2. The best controlling theory is studied and analyzed. The semi-active control force of stay cable is achieved in base of the LQG,LQR,C-LQR methods. Then combining with the stay cable-damper system, we do the simulated analysis. In contrast to the decay condition of the displacement-time curve, the displacement amplitude of measured point under the different control force is achieved. Then the calculation model of relatively better control force is determined which is also called the calculation method of LQR control force.3. Based on the damper model, LQG and LQR method, the semi-active control force is calculated out. A group of wind loads at random is simulated. Under this condition, the influence of the action position to the control effect is in verification when the stay cable is under the different force.4. Under the Matlab environment, the state space equation of MR damper-stay cable is established. Combining with the preceding calculation results, the feedback control loop is designed in the Simulink environment. Meanwhile, in base of LQR feedback control force, and combining with the actual situation of output force, we propose the form of semi-active force accord with the actual project. Then by help of emulation, this force is exerted into the model through the S-function editing platform. The control effect of this method for the vibration of stay cable is in verification. Finally, the conclusion of thesis is summarized, and some suggestions and prospects are pointed out.