Study Of Wind Field In Complex Terrain And Its Influence On The Flow Field Around The Structure

With the rapid development of the bridge industry,more and more complex terrains need to be crossed by large-span bridges.The complex geographical conditions in mountainous areas will cause large temporal and spatial differences in wind parameters,and at the same time will cause deviations between the recommended values of some specifications and the actual values.And as the bridge span increases,the wind sensitivity of bridge structure also increases.Therefore,it is important to summarize the wind characteristics under complex terrain,and to study the windinduced vibration of bridges under the complex terrain.First,based on the field measured data,the basic wind parameters of a mountainous area were analyzed in time and space.The changing laws and reasons of basic wind parameters were summarized.The study found that the form and parameters of the local wind profile are different from those recommended in the specification.And the wind profile will change with changes in topography and atmospheric conditions.When the wind profile accelerates,the effect of increasing wind speed in both the vertical and horizontal directions is caused.The statistical analysis of wind parameters at different locations in the valley reveals that wind parameters along the vertical and horizontal directions of the valley also have temporal and spatial differences,accompanied by obvious seasonal changes.Subsequently,based on the monitoring and analysis results,the changes in wind speed along the span of the bridge were simulated in Fluent through user-defined functions.The square column was used as the research object to study the aerodynamic force of the structure and the changes in the surrounding flow field under non-uniform spanwise wind speeds.The result was compared with the calculation results of the wind speed uniform flow field.The study found that under non-uniform incoming wind speed,the RMS values of aerodynamic forces and aerodynamic coefficients are different along the span,and the aerodynamic correlation decreases with the change of spanwise position.The time-frequency characteristics of aerodynamic forces at different cross-sections are affected by the incoming wind speed,and there is phase difference.As the difference of spanwise wind speed increases,the vortex detachment frequency and phase of different positions in spanwise direction are different,which changes the aerodynamic force of the whole structure.At the same time,under the condition of non-uniform inflow,the disturbance of the structural wake gradually increases,and there are big differences in the vortex shape and shedding form under the condition of uniform inflow.