Extreme Wind Pressure On The Surface Of Large-span Roofs Structure Based On Large Eddy Simulation

The characteristics of light weight,high flexibility,low natural frequency and low damping of the large-span roofs structure determine that it is a wind-sensitive structure.At the same time,its height is often relatively low,and it is in a wind field with a large wind speed gradient and high turbulence.The area caused by the complex surface air flow,frequent flow separation,reattachment,vortex shedding and other phenomena,causing damage to local areas.CFD numerical simulation is time-consuming and low-cost.It can obtain information such as wind pressure at any position on the surface of the structure,and is widely used in engineering practice.Therefore,this paper takes two types of typical large-span roof structures—open stadiums and closed coal sheds as the research objects,and uses large eddy simulation methods to study the extreme wind pressure on the surface of large-span roofs structures.The main research content and conclusions are as follows:（1）The random number cycle pre-simulation method is used to generate inlet boundary conditions and applied to the large eddy simulation of the TUU standard model.By comparing the simulation results with wind tunnel test values and field measured values,the large eddy simulation results can be compared with the wind tunnel test and the field measured average wind pressure,fluctuating wind pressure and peak wind pressure are in good agreement.Therefore,it can be considered that the large eddy simulation method used in this paper can accurately reflect the dynamic wind pressure on the full-scale building surface.Pre-simulation method to generate atmospheric boundary layer turbulence as the entrance boundary condition of large eddy simulation has accuracy and applicability.（2）Research on the distribution characteristics of extreme wind pressure on the surface of an open stadium.Take a stadium in Guiyang as an example.First,use five common distributions to fit the probability density of wind pressure at typical measurement points on the surface of the stadium.Fitting effect of the measuring points;secondly,based on the calculation results of the open stadium,determine the range of skewness and kurtosis,as the standard for dividing the Gaussian and non-Gaussian areas of the open stadium,and perform the calculation on the roof surface of the open stadium.Gaussian area and non-Gaussian area are divided;once again comparing the accuracy of different extreme value calculation methods,it is found that the modified Hermite moment model method has higher calculation accuracy;finally,the influence of roughness on the extreme wind pressure distribution on the surface of the open stadium is studied,and the roof is found The surface roughness will affect the maximum wind pressure coefficient distribution of the open stadium in a local area.Considering that the surface roughness of the structure will reduce the maximum wind pressure coefficient in the local area,it will have little effect on the minimum wind pressure coefficient distribution.（2）Research on the distribution characteristics of extreme wind pressure on the surface of a closed coal shed.Take the coal shed of the third phase coal yard closed renovation project of Zhenjiang Power Co.,Ltd.as an example.First,use five common distributions to determine the probability density of wind pressure at different measurement points on the surface of the coal shed.Perform fitting and analyze the fitting effect of each distribution on different measurement points;secondly,based on the calculation results of the closed coal shed,determine the value range of skewness and kurtosis as the standard for dividing the closed coal shed into Gaussian and non-Gaussian regions.The surface of the closed coal shed is divided into Gaussian and non-Gaussian regions;once again,the accuracy of different extreme value calculation methods is compared,and it is found that the modified Hermite moment model method has a higher calculation accuracy;finally,the influence of local openings in the closed coal shed is considered,and it is found that the current When the direction is perpendicular to the direction of the skylight,a large amount of airflow directly flows into and out of the coal shed through the skylight and the lower vent,so that the direction of the wind on the inner surface of the coal shed is opposite to the direction of the wind on the outer surface,so that the wind on the surface of the coal shed after partial openings The absolute value of the extreme pressure coefficient decreases,and the wind effect on the surface of the coal shed becomes smaller.