The Dynamic Characteristics And Vibration Reduction Of The Cable Network System Composed By Stay Cable And Auxiliary Cable

With the development of economy and the progress of science, the bridge is now well towards to the direction of long span, in the modern traffic system cable-stayed bridge plays an increasingly important role, moreover the main stress component of cable-stayed bridge is stay cable. Because stay cable has many features, such as light quality, low damping, large flexibility etc. Easily producing various types of harmful vibrations under the stimulus of the outside. The vibrations of stay cable will cause the fatigue damage and even destroy at the anchor end, accordingly affect the normal use of bridge, therefore how to control the vibration of stay cables effectively is one of the most important topic of current bridge dynamics. The commonly used vibration measures in cable system is as follows:The traditional air-operated measures, set the concentrated damper, set the auxiliary cable. Stay cable has been divided into sections by the auxiliary cable, thereby improving the rigidity of the stay cables. In the meantime, through connecting the space structure of stay-cables independently to each other, a cable network system has been formed to improve the integral stiffness of the cable. Setting auxiliary cable can’t improve the energy dissipation capacity of the cable network system, the effect of the vibration inhibiting still have some limitations. Instilling concentration of damping at the auxiliary cable end or the joint of the auxiliary cable and stay cable can improve the damping of the cable network system, So that the effect of the vibration inhibiting can be significantly improved.The dumping mechanism of the cable network system of the stay cable and auxiliary cable still lack of reliable theory basis, especially in the selection of parameters and optimizing aspect is not perfect. In this paper, we have analysis the selection of auxiliary cable parameters by means of the combination of theoretical analysis and finite element simulation method, and the influence law of the effect of the auxiliary cable of different parameters impact on the cable network system of the stay cable and auxiliary cable, and the choice of the type of concentrated damper and the selection of the location as well as the optimizing.This paper takes the soil and water conservation of Jialing River min-span stay cable as the research background. First analysis the static and dynamic of one single stay-cable and established the theoretical model of one single cable, and established the finite element simulation model. Take the advantage of the finite element software ANSYS to simulating the dynamic of one single stay-cables. Considering the cable sag effect and damping effect on the cable of each order modal frequency, damping ratio and the shape of vibration. Secondly is the theoretical research on the vibration reduction mechanism of auxiliary cable, through the finite element simulation model of the auxiliary cable to analyzing what the influence law of the dynamic characteristics of cable net structure by the tensioning measures, installation point, the area of the section and the initial stretching tension parameters. Then establish the free modal parameters of the cable net system. Through comparing the modal frequency and modal damping ratio, by means of the two modal parameter to analysis two different vibration equations, and combined with the boundary equation, the deformation coordinate condition and the equilibrium equation to get the vibration modal of the system. Through how the approximate analytic expression to effect the modal frequency and damping ratio of the system by the integral stiffness and the damper stiffness of cable net. Proposed two centralized vibration damper which can be used in vibration of the cable net. And determined the arrangement of the damper. Through ANSYS software simulation model is established, getting the vibration of the two kinds of damper with the by analyzing the two kinds of modal parameters. Finally, taking the modal damping ratio and the modal frequency as the index proposed the optimization ideas of the damper.