风雨激振中斜拉索倾角对水线及拉索振动的影响

The effects of cable inclination on rivulet and rain-wind induced vibration of stay cable

应用基于滑移理论的两自由度风雨激振模型,借助Comsol软件求解水膜运动方程中的风压力系数和风摩擦力系数,通过数值求解耦合的水膜运动方程和拉索振动方程,得到了不同倾角的斜拉索表面的上水线运动规律、拉索气动力变化规律及其振动响应;通过分析三者之间的内在联系探究拉索倾斜角度对风雨激振的影响。结果表明:斜拉索倾角对于起振风速区间的影响不大;拉索横风向及顺风向振幅均随倾角的增大而减小;上水线振荡频率在拉索倾角较小时接近拉索的自振频率,而当倾角较大时远大于拉索的自振频率;上水线在拉索自振频率附近的振荡幅度随拉索倾角的增大而逐渐减弱,导致气动力变化在拉索自振频率附近的能量越来越小,致使拉索振幅不断减小。

The wind pressure and friction coefficients in water film motion equation of2-DOF rain-wind induced vibration(RWIV)model based on lubrication theory are obtained by the commercial software--Comsol in this paper.The characteristics of upper rivulet movements,aerodynamic forces and vibrations of cable are investigated by numerically solving the coupled e-quations of water film and cable.Through discussing their relationships,the effects of cable inclination on RWIV are investiga-ted.The results show that the cable inclination has little influence on wind speed intervals of RWIV and both across-wind and along-wind vibrations of the cables decrease with the increasing of the cable inclination.For smaller inclination,the oscillation frequency of upper rivulet is close to the cable natural frequency,while the former is much higher than the latter with larger in-clination.The oscillation amplitude of the upper rivulet around cable natural frequency is weakened gradually with the inclina-tion increasing,which causes the energy of the aerodynamic force oscillations around the cable natural frequency less and less,meaning the amplitude of cable vibration becomes smaller and smaller.