Research On Wind Pressure Characteristics Of Industrial Buildings Under The Thunderstorm Downburst

Downburst is a very destructive extreme strong wind that often occurs during the thunderstorms.It is a short-term local strong wind that damages the building structure near the ground.Since the research scholars defined downbursts from a meteorological point of view,there have been many reports about on wind-induced damage caused by downbursts such as towering structures and transmission towers.With the continuous improvement of the structural wind engineering field,domestic and foreign scholars have conducted a series of researches on downburst storms such as site monitoring,theoretical analysis,wind tunnel experiments and numerical simulations on their wind fields and wind loads.Previous studies on downburst storm wind loads have mostly focused on high-rise buildings or high-rise structures.There have been few researches on low-rise buildings such as factories;moreover,most of the previous studies focused on static downburst storms.However,measured data indicate that storm centers have it is moving with time.In view of the above problems,this paper takes a single-span industrial plant as the research object,and based on the wind tunnel test,large eddy simulation method,and Reynolds average method analysis,under the action of the downburst,considering radial position,wind direction angle and moving effect parameters on the surface of the plant of the impact of wind pressure.The main research work includes the following sections:（1）Based on the impact jet pressure test and numerical simulation to study the influence of radial distance on the wind pressure on the surface of the flat roof factory,the distribution of wind pressure on the surface of the plant is studied under the action of the downburst.The analysis show that the comparison between numerical simulation and wind tunnel test results is in good agreement and the trend of change is basically the same;under the effect of downburst,the radial distance has a greater influence on the wind pressure on the surface of the building,and the radial distance increases.The average wind pressure coefficient of the plant surface has a significant attenuation trend,and the fluctuating wind pressure coefficient gradually increases.At the radial position of d=0.5D_jet,the surface of the factory building is under positive pressure.At the other radial positions,the windward surface is affected.Positive pressure,the rest of the surface under negative pressure.（2）Establish a numerical wind tunnel and use the Reynolds-Averaged Navier-Stokes method（RANS）and the large eddy simulation method（LES）to consider the influence of different wind direction angles on the wind pressure on the surface of the plant.The analysis show that the wind direction angles are 0°and 90°,and the flow field around the plant is relatively symmetrically,the distribution of wind pressure coefficients on the surface of the factory building is relatively uniform,while in the remaining wind direction angles,conical vortices appear at the wind angles due to the effect of inflow winds,making the distribution of air flow asymmetric,and the surface pressure coefficient is trapezoidal;The surface wind pressure was abruptly changed,and the extreme unfavorable wind pressure region appeared,and the wind-pressure extreme position of each wind direction changed;the change of wind-direction angle made the local area such as eaves,roof,gables and wall corner become extreme wind pressure.In this area,the design wind load should be appropriately enlarged when designing the wind-resistant structure.（3）Based on large eddy simulation,wind pressure characteristics of the plant surface at different spatial locations under the action of downbursts considering the movement effect are studied in numerical wind tunnels.The analysis show that the wind pressure on the surface of the plant under the action of moving downburst shows dynamic changes.At different moments and in different spatial locations,the distribution of the average surface pressure coefficient varies greatly,and the flow field characteristics around the factory building change significantly;when the storm center is located When the building is surrounded by large wind pressures on the windward side and the roof,when designing the low-rise building and other envelope structures,attention should be paid to the impact of the center of the storm on its surface wind pressure.