| According to the number of columns,outdoor billboards can be roughly divided into three categories:independent column,double column and row column.The total height of the independent column billboard can reach 20-30m,the panel width can reach 20m,the height can reach 10m,which exposed its cantilever,towering structural defects,is a typical vulnerable structure.At present,our country designs the billboard according to the technical specification of steel structure of outdoor advertising facilities,which has two disadvantages.First,the superstructure of the billboard is extremely complex and the internal supports are numerous,which brings great inconvenience to the construction.Second,with the rapid development of the advertising industry,the application scope of billboards will not be limited to the type B landform,so it is necessary to consider the wind pressure characteristics of billboards under different landforms to design.In order to get more conducive to the construction and design of three panel billboards of upper structure,and its panel of wind pressure under different geomorphic characteristics,this article through to three different upper structure of independent column billboard according to the scale of 1:20 model,under the A,B,C three kinds of landforms rigid model pressure test,the three kinds of billboards in different physiognomy of wind pressure coefficient were analyzed.First of the three models under different terrain surface average wind pressure distribution were analyzed,the results show that the panel surface wind pressure occurred in the panel edge,the maximum and the direction of its flow front edge back showed a trend of decline,therefore design has three panels billboards in the clearance of the panel,should pay attention to panel on both sides of the edge and the stability of retaining structure and fatigue resistance.The inner surface under three kinds of different terrain model panel 3 has a similar wind pressure distribution,under positive pressure in the middle of the panels,and due to flow through the gap between the panel 1,2,form the high-speed airflow role within the panel 3 surface directly,and then to the panel on both sides of the rapidly spreading,and itself in the panel 3 top and bottom edges of the wake interaction,therefore when designing such a billboard,should consider the interaction between panel.Second,the comparison and analysis for three kinds of billboards panel under A,B,C three kinds of landforms of fluctuating wind pressure distribution,the results show that three models on external surface of the panel,1 and 2 pulsating wind pressure distribution and its average wind pressure distribution law,as the pulse energy attenuation,fluctuating values from the front panel to flow to the rear panel,and the average wind pressure distribution of fluctuating wind pressure on the front panel only A small number of maximum value,the rest of the fluctuating values are between 0.1 to 0.15,the average wind pressure panel contour change gradient is more obvious.Three kinds of billboard panel 3 inner surface near the column to buy Toshiba are greater than other areas,so we can not ignore the column to the impact of the flow.Finally,the maximum and minimum wind pressure coefficients of panel 1 in upwind edge region,middle region and downwind edge region are studied.The results show that the plugging significantly increases the upwind minimum wind pressure coefficient and reaches the maximum value near the 40°wind direction Angle.The existence of the gap increases the minimum wind pressure coefficient of the edge area of downwind,while the middle area of the panel is basically unaffected by the gap.With the increase of turbulence intensity,the minimum wind pressure coefficient of upwind area increases significantly,while the maximum wind pressure coefficient of the middle part of the panel and the downwind area decreases as the wind Angle increases,and these two areas are less affected by terrain category. |
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