Abstract:

Cables of suspension bridges possess strong nonlinear characteristics under both static and dynamic forces,and,under the boundary excitation with certain frequency ratio,they may perform parametric vibration with the amplitude being much more than the initial value.In order to solve this problem,a parametric vibration model of suspender cable, which takes the bridge deck vibration as the boundary excitation and considers the first two or-der modals,was established.Then,by taking the super-large Aizhai suspension bridge as an engineering example,the first-order and the second-order parametric vibrations of the suspender cable under boundary excitation in the finished bridge state were analyzed,the same excited conditions and the response characteristics of parametric vibration of the suspender cable were determined by using the multi-scale method and the Runge-Kutta method,and the effects of excitation amplitude,cable length and initial disturbance on the resonant response amplitude were in-vestigated.The results indicate that the suspender cable of long-span suspension bridges under deck vibration may perfoIm a parametric vibration with the vibration ratio of 1:1 or 1:2,and that the excitation amplitude,the cable length and the initial disturbance affect the response amplitude and the response time to a certain degree.

Key words: bridge engineering, suspension bridges, suspender cable, parametric vibration, multi-scale method, response