Large Eddy Simulation Of Wind Load On The Surface Of A Large Span Roof

The large span roof structure has beautiful appearance and wide interior space,with the development and utilization of lightweight and high strength new building materials,the large span roof structure is developed in the direction of lightness,growth and complication.Due to its large flexibility,small stiffness,small damping ratio and low frequency of vibration,the wind pressure distribution and turbulence fluctuation in the complex flow with high Reynolds number and turbulent characteristics of large span roof surface are the main factors of structural safety.Through the traditional wind tunnel test can be in the architectural design phase of large span roof surface wind load size and distribution form of a forecast,but it takes a lot of human and material resources,with the development of computational fluid dynamics,it has become a trend to predict the wind load of buildings by numerical method.based on the method of large eddy simulation(LES)and combined with computational wind Engineering(CWE),the wind load distribution and flow pattern of flat roof,spherical roof,saddle roof and cantilevered roof are studied,mainly do the following.The grid subdivision aspect:By using the commercial software Icem CFD,the structural meshes of four kinds of long-span roof structures are analyzed,concrete has the following several aspects:The structural mesh of spherical roof is realized by dividing the boundary layer of the outer "O"block in the "O" shape division.Using "Block collapse" and "Y" type subdivision,the saddle roof is divided into grids and three different structural grid method.The structure of cantilevered roof is divided into grids by using "Y" profile,so as to realize the fine depiction of the triangular cantilever part meshes.To simulate natural wind field:As close to the natural wind field of the turbulent flow conditions.The velocity,turbulent kinetic energy and turbulent dissipation rate of the turbulent flow at the inlet boundary are programmed by the user-defined command(UDF)module of the commercial software FLUENT.Numerical study on surface wind load of four kinds of long-span roof structures:(1)The velocity vector around the large-span flat roof,the wind pressure distribution on the roof surface and the streamline form of the vortex core are analyzed,and the feasibility of the large eddy simulation method in the study of wind load on the surface of Long-span roof structure is verified by comparing with the experimental results.(2)Using the Hangzhou International Conference Center as the spherical roof model,the results show that except the leeward surface,the wind pressure distribution of the other surfaces is more uniform,the flow form of spherical roof is more complex,especially the two large spherical vortex cores will have great influence on the surrounding area.(3)Using the same saddle roof as the calculation model,0 degrees,45 degrees,90 degrees,these three different wind angles of the numerical calculation,through the calculation results that the 45-degree wind angle of the flow form than the other two wind angle simple,in the construction of the saddle roof should pay attention to the construction site of the perennial wind direction.(4)Two typical cantilevered roof structures with closed and open openings are chosen as the research objects,at the most unfavorable wind angle(0 degrees),the calculation results show that the wind pressure distribution on the surface of the roof is mainly negative pressure,and the pressure gradient in the middle of the windward surface is the biggest,the area of the maximum wind pressure area in closed form is larger than the open form and the flow area of the tail flow is slightly larger.