Reseacrh On Optimization Technology Of Wind Load On Cantilevered Edge Of Large Span Spatial Structure

As a modern new building structure,the large-span spatial structure is widely used in large public buildings such as stadiums and railway stations.Its structural features are: large span,softness and small quality,so it has some design concepts with traditional reinforced concrete buildings.Differently,its main control load is wind load.The wind field of long-span spatial structure has obvious three-dimensional characteristics,and the characteristics of flow field are complex.The front edge of the roof is subjected to wind loads,which are prone to separation,reattachment,bluff body flow,and vortex shedding at the tail of the roof.The flow pattern and vortex are directly related to the structural form.Therefore,the distribution of the cantilever flow field is critical to the overall wind resistance of the structure.At present,there are three main methods for wind-structure testing,numerical simulation and field measurement.Among them,wind tunnel test and numerical simulation are the main methods at this stage.Wind tunnel test research has been invested in civil engineering wind resistance research since the 1950 s.It has a history of more than 60 years of development,and its specific theory and method are relatively mature.Numerical simulations emerged as computer levels increased and began in the 1980 s.Although the numerical simulation has a short development time,its unique advantages have quickly become a hot spot in the research and development of wind engineering.In this paper,numerical simulation method is used to numerically simulate the crescent-shaped convex roof with finite element software Ansys-Fluent,and analyze the wind load distribution law under different wind direction angles,mainly to carry out the following work:1)Based on the analysis of the backwind roof flow field,the most unfavorable wind direction angle of the structure is obtained by analyzing the backwind roof flow field under the cover of upwind roof.2)At the front of the cantilever,aerodynamic measures(such as opening angle grid,opening the front of the cantilever,adding down edge)are used to discuss the shedding rule of the wind load flow field,and then to optimize the design of the wind load of the structure according to the structural characteristics.It is found that when the inflow and roof are 30 °,45 °and 60 °,the backwind roof is under the most unfavorable load control and the roof front appears the phenomenon of "upper suction and lower roof".After the vents are arranged in the front and two wings of the crescent convex roof,the airflow flow between the upper and lower surfaces of the roof can be effectively penetrated,the influence of the separation of the airflow in the front of the roof on the roof can be reduced,and the wind pressure distribution on the upper and lower surfaces of the roof can be effectively improved.Is the simplest and most effective anti-wind measures.