Research On Cable-Bridge Coupling Vibration Characteristics Based On Catenary

The cable stays will undergo large-scale low-frequency vibration under bridge deck excitation and wind-rain excitation,which will bring great harm to the normal operation of cable-stayed bridges.Therefore,the study of cable vibration has important theoretical significance and engineering practice value.Many scholars at home and abroad have done a lot of research on the mechanism and vibration characteristics of cable-stayed,but the research on cable-bridge coupled vibration system is still not comprehensive.Based on the existing theory,the cable-bridge coupled vibration model based on catenary is established and its vibration characteristics are analyzed.A theoretical model of wind-rain induced vibration of continuous elastic cables based on catenary static line shape considering only in-plane vibration is established,and the characteristics of wind-rain induced vibration of cables under different wind speeds are analyzed.The results show that the vibration amplitude of stay cables is related to the wind speed range under wind and rain loads,and shows the characteristics of "limit" and "speed limit".The in-plane parametric vibration characteristics of stay cables under axial displacement excitation are studied.The effects of frequency ratio,excitation amplitude and damping on in-plane parametric vibration and primary resonance of stay cables under axial excitation are analyzed.The results show that with the increase of the initial displacement of the bridge deck,the vibration amplitude of the cables and the bridge deck increases,and the number of "beating" of the cables and the bridge deck increases in the same time,and the time to reach the maximum amplitude in each cycle is also shortened.By considering the interaction between bridge deck and cable,a theoretical model of coupled vibration of continuous elastic cable under bridge deck excitation is established.The effects of frequency ratio,initial displacement and damping ratio on the vibration of cable and bridge deck coupling parameters are analyzed.The results show that under parametric resonance,the vibration amplitude of the cable is larger than that of the main resonance;the initial displacement of the bridge deck has a greater influence on the vibration amplitude of the cable.The differential equations of cable motion and line motion under the combined action of bridge deck excitation and wind-rain excitation are established.The coupled differential equations of cable motion and line motion are solved by Runge-Kutta method,and the vibration characteristics of the first nine modes of cable-stayed cables under the combined action of deck excitation and wind-rain excitation are studied.The results show that the cable can still undergo large-scale parametric resonance and main resonance,and then gradually transform into cable wind-induced vibration,and the bridge surface excitation inhibits the occurrence of cable wind-induced vibration to some extent.Under the initial bridge deck excitation,the cable vibration modes change,the higher mode is also involved in the vibration.The cable vibration response in the second,third and fourth modes is more obvious.The results are consistent with the actual vibration of cables,which provides a reference for further study on the mechanism of cable-bridge coupling vibration.