Effect Of Fa?ade Horizontal Overhanging Plates On Aerodynamic Characteristics Of High-rise Buildings

With the development of the industry and the improvement of construction technology,building height records constantly refreshed.Due to the increase of the population density and the lack of land resources,high-rise and super high-rise building which can satisfy the living needs and meet the demand of aesthetic structure will predictably become the mainstream of the current and future construction.Since the buildings with square section always have weak aerodynamic performance,they are infrequently used in the design of super high-rise buildings.Therefore,this paper focuses on investigating the aerodynamic performance of square-section building with fa?ade appurtenance.Different types of horizontal overhanging plates are selected and the effect of them on aerodynamic performance,such as wind pressure and loads,are compared.The effects of horizontal overhanging plates on local peak wind pressures were investigated through a series of wind tunnel experiments.Totally 21 appurtena nces arrangements with different horizontal plates were studied.The unfavorable wind directions causing the largest peak pressure and the locations of the largest peak pressure were checked.It is noted that the locations of largest positive peak pressure s can be strongly affected by the changes of vertical distance of horizontal overhanging plates.The area of large positive peak pressures of the models with horizontal overhanging plates can be greatly smaller than the model without horizontal overhanging plates.It is also found that the largest negative peak pressure on the higher leading corner can be mostly reduced by about 40% from the referential condition.By further checking the first four orders of moment of the probability density distribution of the pressure at upper leading corner,it is found that the horizontal overhanging plates can strongly affect the characteristics of the probability distribution.The results also showed that the horizontal overhanging plates can not only reduce the negative local peak pressure of the higher leading corner on side face,but also dramatically reduce the variation range of negative peak pressure on the whole side face.“Zigzag variations” of layer forces can be found in both along-wind and cross-wind when vertical separation distance ratio of continuous plates is larger than 4%.The horizontal overhanging plates can significantly reduce fluctuating pressures on side fa?ade but show different effect on fluctuating cross-wind layer force.The reason of such results is further discussed in this study.The results of power spectra indicate that horizontal overhanging plates show negligible effects on period of vortex shedding.But the peaks of power spectra of models equipped with horizontal overhanging plates become slightly higher than smooth surface model,and the band widths also become narrower.Such results indicate that horizontal plates may result in better organization of vortex shedding by restricting the flow in vertical direction and reduce intensity of vortex.By further checking the correlation coefficients between pressures in same level,it is found that correlations between different positions for models with horizontal overhanging plates become higher than that for smooth surface model.