Analysis Of Wind-rain-induced Vibration Of Stay Cables Considering Fluctuating Wind And Study On Hybrid Damping Measures

Stayed cables are main load-carrying members of cable-stayed bridge;they are easily excited by external loads due to their light weight and high flexibility.Excessive vibration of the cables can lead to cracking and failure of HDPE sheath of the cables,which may cause the corrosion of steel wire by intrusion of vapor or corrosive agent.The corrosion of high strength steel wire would shorten service life of the cables and bring safety risks to the cable-stayed bridge.It is important to control the vibration and predict the response of the cables.In this paper,the vibration response of free cable under wind-rain excitation was analyzed by utilized the fluctuating wind field generate by frequency-wavenumber spectrum,then a hybrid application of viscous dampers(VD)and tuned mass dampers(TMD)was proposed,and the dynamics of the hybrid system was studied.The main elements are as follows:In Chapter 2,a SDOF wind-rain excitation model which take into account the influence of mean wind and fluctuating wind on cable is developed.The fluctuating wind field is simulated by spectral representation method,then the aerodynamic force of cable under average wind and fluctuating wind is calculated.The motion equations of the cable are solved by the RuggeKutta-Felhberg method,the amplitude of the cable under wind-rain excitation are calculated and compared with the measured data.The comparison results confirmed that the wind-rain excitation model which take the fluctuating wind into consideration can accurately predict the vibration response of the cable.Chapter 3 established the TMD-cable model and mainly analyzed the dynamics property of the new mode which introduced by the attachment of TMD.It is found that the dynamics property of introduced mode is quite different to that of other modes.The frequency ratio of TMD is the major parameter effecting the frequency of the introduced mode,while the change of other parameters has little effect.With a clear understanding of the characteristics of the TMD-cable system,the VD-TMD-cable system model is further established and studied.The effect of parameters on the damping characteristics of the hybrid system is studied by numerical method.The limit solution of the hybrid system is classified and discussed,and the mode behaviors of the introduced mode and the original mode are analyzed by using the limit solution.It is found that,the regimes of the introduced mode are more than the original mode,so the mode behaviors of introduced mode are more complicated.Chapter 5 proposes a simplified parameter optimization method for the hybrid system based on the results of the parameter studies in Chapter 4.This method can greatly reduce the computational cost of parameter optimization process by optimizing the parameters of TMD and VD respectively.The simplified optimization method and the conventional are applied to the same example,and the optimization results are compared to verify the accuracy and effectiveness of the simplified parameter optimization method.