Three Dimentional Vortex Induced Vibration Research Of Long-span Bridge Based On Section Model Test

With the increasing traffic demand and the widespread adoption of high-strength materials,bridges are becoming larger,lighter and thinner,and the possibility of wind-induced vibrations under the action of wind loads is gradually increasing.In recent years,many largespan bridges,including Xihoumen Bridge and Humen Bridge,have experienced vortexinduced vibration problems to varying degrees.Therefore,it is particularly important to accurately evaluate the vortex-induced vibration performance of long-span bridges and propose corresponding vibration suppression measures in actual engineering.At present,in the research and practice of bridge vortex vibration performance,the segment model wind tunnel test is mainly used.However,the actual bridge is a three-dimensional structure.How to use the results of the quasi-two-dimensional segment model wind tunnel test to evaluate the vortex vibration performance of the three-dimensional real bridge has been the focus of bridge wind engineering.This article introduces three vortex vibration analysis theories,including the vortex vibration analysis theory that only considers the influence of the mode shape and the three-dimensional vortex induced vibration analysis method of the long-span bridge considering the cross-directional correlation of the mode shape and the vortex induced force proposed by Eshan and Sun.Based on the segment model and the brace model wind tunnel test,the application research of these vortex vibration analysis methods is carried out,and the advantages and disadvantages of each method and the prediction accuracy are compared.The following is the main work of this dissertation:1.The development history of long-span bridges was briefly explained,the problems of bridge vortex induced resonance were discussed,several common vortex induced resonance analysis theories were introduced.The empirical linear model and the Scanlan semi-empirical nonlinear model as well as the identification method of the corresponding vortex excitation parameters were introduced.The influencing factors and vibration suppression measures of vortex induced vibration were introduced.Finally,the incomplete correlation characteristics of the vortex excitation force along the span direction of the main beam was briefly introduced.2.Several three-dimensional vortex vibration analysis theories for bridges were introduced,including the vortex vibration analysis theory that only considers the effect of mode shape,the vortex vibration analysis theory proposed by Eshan,and the threedimensional long-span bridge vortex-induced vibration analysis theory based on Scanlan semi-empirical linear model and nonlinear model proposed by Sun.And MATLAB programs for calculation of various vortex vibration analysis methods were compiled.3.The wind tunnel test of the 5:1 rectangular section segment model and the wind tunnel test of the equal-scale brace aeroelastic model of the same section were carried out.According to the three vortex vibration analysis theories,the theoretical amplitude of the vortex vibration under different vibration modes of the real bridge was calculated by using the wind tunnel test results of the segment model,and and compared with the wind tunnel test results of the brace aeroelastic model,the reliability of the three theories in practical applications was comparatively analyzed.4.Relying on the actual long-span bridge full-bridge aeroelastic model vortex induced vibration wind tunnel test,verify the feasibility of the three analysis theories in the long-span bridge vortex vibration analysis,and discussed emphatically the influence factors of the vortex vibration analysis method proposed by Sun in the actual bridge application process.