Theoretical Models And Parametric Analysis Of Rain-Wind Induced Vibration Of Stay Cable

The evolution of upper rivulet plays an important role in rain and wind induced vibration(RWIV).So,the study of the interaction between the rivulets and the stay cable is taken as a breakthrough for the phenomenon of RWIV in this paper.The main research contents include:Firstly,based on the vibration equation of string with two sides fixed,an analytical solution of the RWIV is established.According to the practical engineering,the basic parameters are set up into the model.The time history of the cable vibration is obtained by calculating.On this basis,the influence of damping ratio,force,and length of cable are analyzed.Secondly,based on the existing theoretical model,two new thoughts are carried out: a new 2D theoretical model of RWIV is established and the calculation efficiency is improved.On this basis,in order to verify accuracy of the model,evolution of water film around the static cable is calculated under gravity and aerodynamic forces,respectively.Thirdly,based on the experiment of stiff truncated model of stay cable,basic parameters of the equations are set.The equations are solved to get the amplitude of stay cable,aerodynamic forces and heights of upper rivulets under different time.The dominient frequencies of several main parameters are calculated by Fourier transform.Fourthly,with different wind speeds,effects of cable inclination angle,wind yaw angle,cable radius and cable characteristic on RWIV are studied.Amplitude of stay cable,aerodynamic lift,height of upper rivulet the respective frequency spectrum are calculated.Fifthly,a new 3D theoretical model of stiff truncated stay cable is established and effect of stay cable vibration on rivulets is considered.Cable vibrations,aerodynamic forces and some other parameters are simiplified to get the height of water film around the cable at differenent time with finite difference method.Lastly,the 3D coupled equations of cable vibration and rivulet oscillation are established.A typical wind speed of three different wind speed ranges,respectively,is calculated to get the cable vibration amplitude,aerodynamic lift variations and rivulets oscillations.The results show that analytical solutions of RWIV could predict the amplitude of stay cable accurately.At the precondition of keeping precision,using the 2D theoretical model of RWIV could improve the calculation efficiency obviously.Under RWIV,stay cable vibrates with limited amplitude and the large amplitude occurs at limitd wind speed magnitude.Under certain wind speed range,with the increase of inclination angle and wind yaw angle,stay cable amplitude increases first and then drop.With the increase of cable diameter and inherent frequency,stay cable amplitude decreases gradually.The 3D coupled theoretical model of RWIV is accurate and effective.Axial flow phenomenon of water film around the cable can be seen using 3D stay cable theoretical model.The similar dominant frequency of stay cable vibration and upper rivulet oscillation lead to collaborative vibrations between stay cable and upper rivulet,which is the necessary condition for the occurrence of RWIV.