The Influence Of Non-Uniform Wind Field On The Flutter Stability Of Long-Span Suspension Bridges

With the development of traffic construction in China,the great development strategy of the western region has been continuously deepened,and the suspension bridge with large capacity has been widely used to cross the mountain valley in the western region.The characteristics of wind field in mountain canyons are complex,and there are great differences between different bridge sites.In addition,the long-span suspension bridge across the high mountains and valleys is light in weight and soft in structure,which is very sensitive to the role of wind.In order to ensure the safety of bridge construction and the state of the bridge,the flutter stability of the bridge in the uneven wind field of the bridge site must meet the requirements.In this paper,a large-span suspension bridge in a mountainous area is taken as the engineering background.Firstly,Imageware,a reverse engineering software,and Global Mapper,a topographic software,are combined to obtain the 3d elevation information of the topography at the bridge site.Then,mesh division is conducted and imported into FLUENT for solving calculation to obtain the 3D wind field characteristics at the bridge site.Then a simplified canyon model is adopted to further verify and analyze the topographic wind field characteristics of mountain canyons.On this basis,the flutter stability of Bridges under uniform and non-uniform flow field is analyzed by using time-domain and frequency-domain methods respectively,and the problem of parameter selection in the process of flutter solution is discussed.The numerical simulation of topography in this paper shows that when airflow flows through the canyon,due to the fluctuating topography,it is possible to generate a large isthmic effect in the narrow part of the canyon.Simplifying the canyon wind field can effectively simulate the wind speed change rule at the bridge site,and the airflow flowing through the mountain slope in the canyon area will lead to the increase of wind speed and thus cause the local wind speed change.On mountain canyon long-span suspension bridge flutter stability analysis show that the uniform flow of bridge flutter critical wind speed were greater than flutter test wind speed,when the non-uniform wind field bridge flutter performance will change,across the Bridges is significantly influenced by the wind speed will focus in flutter stability,considering nonlinear changes in Angle of attack for accurate evaluation of bridge flutter stability is very important,especially with the Angle of attack change aerodynamic stiffness and aerodynamic damping larger bridge.Bridge flutter Bridges under more frequency in time domain analysis similar to"shoot",vibration phenomenon could occur,the damping can significantly enhance the flutter stability of the bridge,flutter non-uniform wind field in time domain analysis main girder node distribution patterns of the displacement response of change over time,for the study of the actual wind field bridge flutter stability to provide certain reference.