Wind Tunnel Test Research Of Wind Pressure Around The Vulnerable Area On Low-rise Buildings

In recent years, the frequency, intensity and scope of typhoon landed in our country increased year by year. A plenty of low-rise buildings distributed in our country's coastal areas. These buildings located in complex landform and the forms of architectural were variety. Statistics shows that wind-induced damage of low-rise buildings caused by typhoon accounted for more than half of the total wind disaster losses. In the wind storm, local damage at the vulnerable area including roof corners,edges and ridges is easily damaged and caused the overall collapse of the whole building. At present the studies on the quantitative relationship affected by wind angle,turbulence intensity and other wind parameters for wind load characteristics on gable low-rise buildings vulnerable area are relatively few, and our load codes for shape coefficients of low-rise buildings is defined too simple.Therefore,the research of low-rise buildings wind-resistant has very important practical significance.This paper based on the wind tunnel test of gabled roof low-rise buildings with five different slope angles with a 1:20 scale ratio, researched the effect of turbulence intensity and slope angle to change law of wind pressure on low-rise buildings under class A,B and C landscapes. Wind tunnel test results show that the variations of wind pressure coefficients along with azimuths show some regularity and obviously, in oblique wind direction is the most unfavorable wind direction to different slope angle low-rise buildings. In oblique wind direction, wind pressure of roof corner region is relatively higher which is high suction region, the region is easy to damage and form to vulnerable area on low-rise building under the action of strong wind. Slope angle has a great influence on local shape coefficient, the wind pressure extremum area(vulnerable area) is on windward roof edges and corner region to flat roof low-rise building, and to gabled roof low-rise buildings local shape coefficient on leeward ridge of roof is significantly higher than other region, these regions are easy to damage and form to vulnerable area under the action of strong wind. The turbulence intensity has little effect of mean wind pressure on flat roof low-rise building, however it has a great influence on fluctuating and peak pressure coefficients. With the increase of turbulence intensity the mean, fluctuating and peak pressure coefficient will also increase. The turbulence intensity has a great influenceon areas of windward roof edges under mean wind pressure at a wind azimuth of0°and 90°,and it has little influence in oblique wind direction. With the increase of turbulence intensity the wind pressure on windward roof edges and corner region to flat roof low-rise building, and on leeward ridge of roof and gable area to 45°slope angle low-rise building will also increase.According to the Chinese and foreign load codes the surface of the buildings was divided to research the effect of turbulence intensity and slope angle to change law of shape coefficient on low-rise buildings,meanwhile the roof shape coefficients were given. The results show that slope angle has a great influence on local shape coefficient, with the increase of slope angle the absolute value of shape coefficients on windward roof decreases and to 18.4° slope angle low-rise building shape coefficient on leeward ridge is maximum; Different division forms lead to shape coefficient values vary in size and some values in Chinese load code tend to be low, it is not safty when design.