Non-Linear Vibration And Intelligent Semi-Active Control Of Cables For Large-Span Cable-Stayed Bridge

Cable stays are most prone to exhibit oscillations of large amplitude that may be excited by environmental excitations such as wind, wind or rain, support motions etc, due to their small mass, large flexibility, small damping. It will lead to immense economic damage because of change of destroyed cables. On the other hand, large amplitude of vibration can also make passers worry about the safety of bridge. So it is very important to analyze the cable's vibration and to search for the effective control measurements on the vibration.A new model considering the coupling between the cable and bridge deck (or tower) is proposed in the thesis. The nonlinear vibration equations of cables, which are established based on Hamilton's principle, are solved approximately using the multiple scale method. The possibility of 1:1 internal resonance between the in-plane and out-of-plane modes is analyzed. The effects of parameters such as excitation amplitude, frequency, damping, inclined angle etc are discussed in detail. In order to testify the approximate solution, it is compared with the numerical results.The forward and inverse dynamics of MR damper are emulated using neural network. Because of the slow convergence and bad generalization of the trained network by BP algorithm, Levenberg-Marquardt algorithm with 2nd order differential convergence and Byes Regularization method are used together to train the network model of MR. The results show that the method can improve the calculation and generalization of the neural network, the network model of MR damper built here has great adaptability and generalization.A new semi-active neurocontrol method for cable-MR damper system is proposed based on neural network theory. It can thoroughly exert the MR damper's capability of dissipating energy and mitigating vibration under different voltage, so it can realize MR damper's thorough state control on vibration of cables. Through the numerical analysis of the typical cables in real cable-stayed bridge, the good control effects of this method are proved. At the same time, it is compared with LQR active control method.A new semi-active fuzzy control strategy for cable-MR damper system is proposed based on fuzzy logic theory, in which the control voltage to MR damper is given directly by fuzzy controller. The method works simply and practically. In order to testify its effectiveness, many cases, such as responses of cables under different loads, different amplitude or frequency for the same excitation etc for two typical cables in real cable-stayed bridge are calculated. At the same time, the comparison between semi-active fuzzy control and other control methods, such as semi-active neurocontrol, LQR active control and passive control is also done.