Study On The Wind Pressure Characteristics Of Circular Hyperboloid Roof Under The Action Of Moving Downburst

Downburst is a kind of natural phenomenon with explosive strength and large destructive power.The strong air generated by a downburst hitting the ground can cause great damage to buildings,power towers,etc.Similar strong winds often occur in our country.The current load codes in China do not refer to the strong wind loads similar to the downburst.Therefore,it is necessary to study the downburst.At the moment,many large stadiums involve long spans.The large size and prominent shape of the long-span structure make it easy to see the phenomenon of airflow separation and re-attachment when the strong wind impact is similar to the downburst.It is easy to generate strong wind suction.The roof height of a long-span structure is often close to the height at which the downburst is fully developed,And the downburst impinges on the building and produces wind loads different from the traditional atmospheric boundary layer.The effect of a downburst flow through an irregular roof is quite different from that of a regular roof.In reality,storms are mostly accompanied by the movement of clouds.The cloud movement will affect the wind field near the ground,and then change the influence on the wind pressure of the roof of the building.At present,there are few studies on the surface wind pressure of long-span irregular roof under the action of downburst.In view of the research status of downburst,the main research work in this paper is as follows:(1)With the help of CFD software,research is carried out on mobile downburst.Based on the impingement jet and the SST K-ω turbulence model,a scale calculation domain was established for calculation.Firstly,dynamic grid technology is used to simulate the motion process of downburst,and wind field characteristics at Z= 0.3d JET height are analyzed.The results were compared with previous research results to verify the reliability of the simulation,and then the wind field near the building was further calculated and analyzed.(2)In the process of downburst movement,the change of roof wind pressure under different moving speeds and offset distances was compared and analyzed to explore the effect of storm speed and offset distance on roof wind pressure.Then the influence of slope and building position on roof wind pressure was further studied.(3)The influence of the building shape on the roof wind pressure is considered,and the effect of the factors influencing the building span ratio height to span ratio is explored to provide theoretical support for building design.The results show: The dynamic grid technique can well simulate the motion process of downburst.The movement of the downburst has a certain acceleration effect on the leading edge of the storm and a deceleration effect on the rear of the storm.The high point area of circular saddle roof is greatly affected by parameters.The middle area of the roof is less affected by the parameters.