The Parametric Vibration Of Stay Cable And Dynamical Analysis Of The Cable-Stayed Bridge

The stay cable is one of the principal force members of cable-stayed bridges . Because of the vibration of bridge tower and bridge floor, the tensile force of the stay cable would be changed cyclically on the action of wind, earthquake and traffic load. Accompanying with the vibration of bridge tower and bridge floor, the stay cable can vibrate in a large range, which may take grate danger to the reliability and endurance of the stay cable. So we need to do deeply research on dynamic features of the stay cable in order to make solid foundation of the design of cable-stayed bridges and vibration control of the stay cable.This paper introduced vibration theory on horizontal tension cable and the stay cable related to parametric vibration of stay cable , Through the finite element analysis, it researched the mechanism of parametric vibration, analyzed parametric vibration of the stay cable on the action of displacement load at the cable end, discussed the effects of vibration amplitude of the stay cable under the affection of sag, damping ratio etc, and build the coupling vibration differential equations of the stay cable-bridge floor system. The result shows that parametric vibration is on the condition that the vertical vibration frequency of bridge floor is two times to the transverse vibration frequency of the stay cable. If the stay cable-bridge floor system reaches above condition, Any tiny vibration of bridge floor may promote great transverse vibration of the stay cable, the damping of the stay cable can't decrease its great transverse vibration at initial vibration stage effectively, so we need to add suitable adscititious damping to the stay cable for controlling its transverse vibration.In another side, this paper made analysis about a cable-stayed bridges, which mainly analyzed its dynamic response on the action of moving load and discussed its dynamic coefficient.