镂空双层幕墙对高层建筑结构风响应的影响

Effects of porous double skin faade system on structural wind responses of tall buildings

摘要:

镂空双层幕墙以建筑节能与美学方面的突出优点日益得到建筑界与工程界的青睐。镂空层具有柔化建筑角部气流分离的作用,对控制高层建筑的风振响应也应产生有利影响。为此以一栋典型方形高层建筑的风振加速度和结构风荷载为例,通过详细的风洞试验研究了镂空双层幕墙的效果,重点研究镂空双层幕墙覆盖面积与覆盖位置的影响,同时考察了不同类别场地的影响。研究结果证实了镂空双层幕墙在抑制建筑横风向响应方面的有效性,特别是当镂空双层幕墙位于建筑物上部且覆盖至少1/6总高度时有效性更为显著。同时发现镂空双层幕墙的有效性随约化风速（无量纲参数）不同而有所变化。当约化风速＜10.5时,覆盖建筑物上部1/3高度的镂空双层幕墙可使建筑物的加速度降低20％～30％。当约化风速＞10.5时,风振加速度和结构风荷载则可以降低多达45％。这表明镂空双层幕墙不仅可以用于降低极端风下的结构设计风荷载,而且可用于改善建筑物在常遇风条件下的运营品质。风洞试验结果还表明,不同场地条件下镂空双层幕墙在减少横风向响应方面的效果基本类似。因此,在建筑优化设计中可以将镂空双层幕墙考虑为对现有建筑空气动力学优化方法的一个理想补充。

Abstract:

Due to the strengths of porous double skin faade (porous DSF) systems in building energy efficiency and architectural aesthetics, they have become increasingly popular in the architectural and engineering fields. Given the fact that porous DSF can soften the flow separation around building corners, it is expected that porous DSF systems should have the potential in controlling wind-induced structural responses. Therefore, a detailed wind tunnel study was conducted to investigate the effects of porous DSF on the wind-induced accelerations and structural wind loads of a typical square tall building, focusing on the influence of the porous DSF coverage area and its location. The performance of the porous DSF under different terrain conditions was also examined during the wind tunnel tests. Research results confirmed the effectiveness of the porous DSF in suppressing the across-wind responses of buildings, especially when the porous DSF located in the upper part of the building and covered at least 1/6 of the total height. It was also found that the effectiveness of the porous DSF varied with reduced wind velocity (a non-dimensional parameter). When the reduced wind velocity was lower than 10.5, the porous DSF system covering the upper 1/3 of the building height could reduce the building acceleration by 20% to 30%. When the reduced wind velocity was higher than 10.5, the building acceleration and structural wind loads could both be reduced by up to 45%. It suggests that porous DSF can not only be utilized to reduce the structural design wind loads in extreme wind events, but also be employed to improve the serviceability performance of the building in normal wind conditions. The wind tunnel tests for different terrain conditions revealed similar effects of porous DSF in reducing across-wind responses. Thus, porous DSF systems can be regarded as an ideal supplement to the existing aerodynamic approaches in building optimization design.