双幕墙长矩形建筑风荷载特性的试验研究

以节能、生态为理念的双幕墙围护体系已逐步应用于高层办公建筑中。由于双幕墙之间存在通风廊道,因此对于双幕墙建筑有三个受风表面,即外层幕墙的内表面和外表面以及内幕墙的外表面,这使得风载取值变得复杂,目前也无规范可依。本文通过对杭州市某双幕墙办公楼的风洞试验研究,探讨了双幕墙建筑内、外层幕墙的风载取值问题;研究了门厅大跨挑篷风压分布特征,当风从侧面吹向挑篷时,挑篷上、下表面风载与普通屋盖挑篷相同,而当风从正面吹向挑篷时,挑篷上表面出现正风压,并对此现象进行了分析;文中针对该建筑物长宽比较大的特点,比较了大长宽比矩形建筑风载体型系数与规范给出的正方形建筑风载体型系数:当风沿建筑物长向流动时,采用规范给出的正方形建筑风载体型系数是可行的,当风沿建筑物进深方向流动时,其两侧及背风面的负压比正方形的大。

Wind tunnel test study on wind load characteristics for double-skin facade building with rectangular shape

The double skin facades are applied to multistory office building gradually as people require energy saving and ecotype. For the building with double skin facades, there are three surfaces subjected to wind pressure due to the airflow between the double facades: those are the outside and inside surfaces of the external skin facade and the outside surface of the internal skin facade. Consequently, the wind loads acting on the double skin facades become complicated and can not be obtained from code. In this paper, wind tunnel tests on a double skin facade building in Hangzhou were carried out to study the wind pressure distribution on each surface of the double skin facades. Furthermore, the characteristic of the wind pressure distribution on the long span canopy was also obtained from the tests. When wind is blowing from the side of canopy, the wind load acting on the upper and lower surfaces of the canopy is almost the same as that of the ordinary roof canopy. When wind load is blowing in front of the canopy, positive pressure will appear on the upper surface of the canopy. The structural shape factors of wind load for the building with large length width ratio are compared with those from the Loading Code for Building Structures (GB 50009—2001) for square building. It was found when the wind is blowing along the length of the rectangular building, the shape coefficients given for the square building in the code can also be used in designing rectangular building; while the wind is blowing along the width of the rectangular building,the negative pressure on both sides of the building as well as on the leeward side of the building will be much more larger than those of the square building.