Vortex-induced Vibration Performance Of A Steel Box Girder With Projecting Slab In A Long-span Cable-stayed Bridge

Long-span bridges often cause vortex-induced vibration under low wind speed due to the characteristics of long span,small damping and low natural frequency.Although vortex-induced vibration is a limited vibration with self-excited nature,it brings serious problems to the construction safety and driving safety under the completed bridge state due to its low wind speed and high frequency.In view of the above problems,based on the actual project and the numerical simulation method of two-way fluid structure coupling,this paper studies the vortex-induced vibration performance of a long-span cable-stayed bridge with cantilever steel box girder.The main contents of this paper are as follows:(1)This paper reviewed the development history of long-span bridges,introduced the vortex-induced vibration problems in the high-speed development of long-span bridges,and further expounded the research methods,vortex-induced force model and the research status of vortex-induced vibration reliability.In view of the shortcomings in the current research,the research direction and objectives of this paper were determined.(2)Based on the two-way fluid structure coupling numerical simulation method,the vortex-induced vibration process of the steel box girder with cantilever was analyzed,and its accuracy was verified by comparing with the wind tunnel test results.On this basis,the mechanism of vortex-induced vibration was analyzed.(3)Based on the verified numerical simulation results of two-way fluid solid coupling,the time history of the vortex-induced force of the main girder was extracted,and the mathematical model of the vortex-induced force for the main girder with cantilever was established.Through the fourth-order Runge Kutta method,the vortex-induced response of the steel box girder with cantilever was inverse calculated,and compared with the numerical simulation results,verifying the correctness of the proposed vortex-induced force model.(4)Based on the proposed vortex-induced force model,the vertical bending vortex-induced vibration amplitude formula of the steel box girder with cantilever was derived.Based on the principle of maximum entropy,the method of multiplicative dimensionality reduction was used to analyze the vortex-induced vibration reliability of the main girder in terms of the amplitude failure.