EFFECTS OF SPOILER ON WIND LOAD OF FLAT ROOFS EXPOSED TO SEPARATION BUBBLE

Through wind tunnel test, wind pressure characteristics of flat roofs exposed to separation bubble with or without spoilers were investigated and compared. Based on this, the mechanism of the spoiler for reducing wind-induced effect and the recommended inclination were given. Distribution and statistics of wind pressures were demonstrated. It is shown that the mean and fluctuating pressures are reduced by setting the spoilers, except those near the leading edge. In the separated region, the skewness and kurtosis of wind pressures significantly decrease, which implies the less obvious non-Gaussian nature. The influence of spoilers on wind pressure correlation was analyzed. It is observed that the longitudinal correlation attenuates dramatically, while the degenerative transverse correlation only occurs near the leading edge. The variation of total uplift forces and overturning moment were given. For the spoilers with inclination of 0°, 10° and 20°, the total mean uplift forces are decreased by 6.3%, 8.2% and 6.6% respectively, the total mean overturning moment are decreased by 18.2%, 21.9% and 23.3% respectively. With the obtained wind loads, the static response analysis was conducted. It is demonstrated that the axial force at the column bottom, the moment at the column bottom and the displacement at the roof center can be reduced by up to 13.1%, 15.6% and 10.1% respectively. Based on the statistics, the correlation, the total force, and the structural internal force, the recommended inclination of spoilers on flat roofs is 10° within the investigated scope.