The Study Of Rain-wind-induced Vibration Of Cables In Cable-stayed Bridge

Cables are important constituent parts of cable-stayed bridges and almost all the dead loads and live loads are transferred to the substructure through them. The unique aesthetic characteristics and engineering features of cable-stayed bridges are also embodied in them. Because the mass, stiffness and damping of cables are relatively small, the influences of cable vibration become serious increasingly with the broadening of spans of cable-stayed bridges. In all the circumstances, rain-wind-induced vibration of cables is the most dangerous to structures for its frequent occurrence and its large amplitude. Consequently, rain-wind-induced vibration of cables has been considered by the researchers of bridge engineering and wind engineering.Rain-wind-induced vibration is a kind of large amplitude vibration under rain and wind conditions. The study of rain-wind-induced vibration develops slowly, suffering from the sophisticated relationships between the occurrence of the vibration and these parameters. The main task of this thesis is as follows:(1) The principle of rain-wind-induced vibration is analyzed using nonlinear dynamics. It is based on the analysis of the dynamics model of the cable's rain-wind-induced vibration. According to the influence of the attrition between the cable and waterline on , using the theory of Lagrange, the movement equations of non-conservative cable system are obtained considering the impact of the energy.(2) By solving couple method of Nayfeh, the vibration equations of the system are considered. Both the system which has the square items, the cube items and other higher items and rain-wind-induced vibration which has stable vertical range can be studied.(3) The theoretical analysis of 1:2 internal sympathetic vibrations is carried out by means of multi-scale method. The relationship between the resonance amplitude of cables and the damp is analyzed according to the approximate solutions. Furthermore, the influence of damp compares on the system's vibration is obtained and the results of analytical method are almost coincide with the numerical results.(4) Using the program of mathematica, phase portraits are obtained and the effects of parameters to the vibration of the system are revealed quantitatively in the scale of the value of these parameters. It shows that the damp compares, the density compares, the frequency compares and the location of the waterline are of vital importance to the vibration of the system.