Numerical Study On Nonlinear Vibration Of Cables In Cable-Stayed Bridges

The cable-stayed bridge is widely used in large-span bridges, As the main part to supportthe weight of the bridge, the stayed cable is prone to exhibit vibration of large amplitudeunder the wind, wind-rain or traffic loads due to its flexibility. This oscillation can greatlyaffect the performance of the bridge. So in order to improve the design level of cable-stayedbridge it is important to study the mechanism of the vibration and perform numerical analysis.Considering the sag of the cable, out-of-plan vibration and the oscillation of the bridgedeck, a model of coupled nonlinear vibration of the cable and bridge deck is established. Thenthe governing equations are discretized using Galerkin method and solved through numericalintegration. In this paper an actual cable is taken as an example and detailed computation isperformed on the coupled vibration under various conditions. First, the possibility ofoccurring parametric oscillation is studied. The results show that under certain conditionslarge amplitude vibration may occur because of the oscillation of bridge deck, at the sametime, large amplitude out-of-plan vibration called swing may also appear. The beatphenomena can be seen obviously and the energy transfers from one DOF to another whilethe total keeps constant. It also can be seen from the results that the amplitude of the cable ismainly determined by the amplitude of the bridge deck. Second, the 1:1 harmonic resonanceis studied in this paper. The numerical results indicate that under certain frequency ratio 1:1harmonic resonance may take place with the occurrence of large amplitude out-of-planvibration. Finally, the damping effect is investigated. The results show that for parametricresonance, the amplitude of cable decreases rapidly because of the damping and thedecreasing velocity increases with respect to the increase of damping while 1:1 harmonicresonance does not.Through the numerical study of the non-linear vibration of the stayed cable, moreinformation about non-linear behavior of stayed cable is gotten.