Buffeting Response And Fatigue Damage Analysis Of The Cables In Long-span Cable-stayed Bridge

The fatigue damage of cables for long-span cable-stayed bridges induced by fluctuating wind loads cannot be ignored.In this paper,Jiang-shun Bridge was taken for example,and the wind-induced vibration response and the cable fatigue damage considering the balance position under the static wind loads was researched.The fluctuating wind speed at bridge site was simulated by using the weighted amplitude wave superposition method.Base on ANSYS,the buffeting responses of the bridge was analyzed considering the geometrical non-linearity comprehensively.In order to get the stress amplitude and the corresponding cycle times of the cables,the program of Rain-flow counting method compiled by the software MATLAB was used.Finally,based on the Miner linear cumulative damage theory,the fatigue damage of the cables on the key position was investigated.Meanwhile,the effect of different wind parameters on the fatigue damage of the stay cable was investigated.By using the wind data from meteorological stations,the joint distribution of wind speed and wind direction was fitted,and the fatigue life of the stay cable at the key position under wind loads is evaluated.The main work is as follows:1.By using the measured wind data from weather station,the joint distribution of wind speed and direction at the bridge site was fitted,and it is considered that the wind field at the Jiang-shun bridge site is suitable for the distribution of Gumble,besides it,the joint distribution function of wind speed and direction was obtained,Which can be used for fatigue analysis.2.The finite element model of the beam element and the shell element of Jiang-shun bridge were built by using ANSYS software.Through the equilibrium analysis under the gravity load and the vibration characteristics analysis of the two models,it is considered that the two models can be used for the structural buffeting response analysis,after comprehensive consideration,the beam element was used for research.3.Based on the principle of weighted amplitude wave superposition method,the program compiled by the software MATLAB was used to simulate the fluctuating wind field at each node of the girder and the bridge tower,so the time history of buffeting force can be obtained.Then the study of buffeting response is carried out,and the stress time history of the cable element can be obtained,besides it,the effects of wind speed and wind attack angle on the buffeting response of cable stayed bridge was analyzed.4.In order to get the stress amplitude and the corresponding cycle times of the cables,the program of Rain-flow counting method compiled by the software MATLAB was used.Finally,based on the Miner linear cumulative damage theory,the fatigue damage of the cables on the key position was investigated.Meanwhile,the effect of different wind parameters on the fatigue damage of the stay cable was investigated.The results show that the greater the wind speed and wind attack angle,the greater the fatigue damage of the stay cable,and the cable of maximum fatigue damage is the longest cable of the midspan,and the fatigue life of the cables J22 at windward side and leeward side under wind load was estimated.