The Analysis On Parametic Vibration Of The Stay Cable In The Cable-Stayed Bridge

The stay cable is one of main force members of cable-stayed bridges. Under the loads of the wind, rain, earthquake, vehicles, the strain of the stay cable would be changed by the vibration of the bridge deck and the bridge tower, which could lead the great transverse vibration of cable. It is a great deal of harm to cable-stayed bridge safety. Therefore , it is necessary in-depth study of the vibration characteristics of cables, and it could lay a theoretical basis for vibration control of stay cable.The paper briefly introduces the job done by the domestic and foreign scholars in the stay cable parameter vibration. Then, the mechanism of parameters vibration of the stay cable is studied under the simplified mechanical model by numerical analysis. The characteristics of parametric vibration of the stay cable are analyzed when the end displacement of the cable-stayed bridge is excited by the bridge decks and under cable-bridge coupled action. The vibration differential equations are set up under the tower-cable-bridge coupled vibration and the characteristics of the tower-cable-bridge coupled vibration is studied. The results are shown that the weak vibration on tower or bridge decks can lead the great transverse vibration of cable when the frequency of tower or bridge deck is twice as large as that of natural frequency vibration of cable. The structural damping of the stay cable can not effectively reduce the initial maximum amplitude, so it is necessary to impose extra damping on the stay cable to control the substantial vibration.