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Charcteristics of wind load due to abrupt gust

突发阵风风荷载特征

基本信息

批准号：
06650644
负责人：
KAWAI Hiromasa
金额：
$ 0.9万
依托单位：
Tokyo Denki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650644/
关键词：
Gust Typhoon Damage Conical vortex Roof tile scatter Local suction Change of wind direction 風向変化風荷重

项目摘要

Buildings and houses are often damaged by abrupt gust in a strong wind like a typhoon. Wind suddenly increase to double or triple of a ordinary speed and then decrease gradually in several seconds in such a gust. However, such a abrupt gust wind load is not described in codes of practice in any country in which it is assumed that wind blows stationary in a retativery long time. In this research, effects of the abrupt gust on wind load on a house are investigated by wind tunnel tests mainly from the following two points of view.1) To simulate an abrupt gust in a wind tunnel2) To clarify a mechanism of a wind loading due to the gust.In order to simulate the gust, we set a fence at a position far from a house model with a flat roof. By adjusting a hight of the fence and the distance from the model, an abrupt gust can be produced, which is very similar to the gust in a natural wind. The flow on the roof is influenced significantly and the wind load on the roof suddenly changed by passing the gust. The separated shear layr swept by the gust to produce a very severe local suction on the laeding edge of the roof. In the case of oblique flow, a conical vortex is formed on the roof and flaps in a short time by the abrupt increase of wind speed and a variation of wind direction.

建筑物和房屋经常在强风中被突如其来的阵风损坏，比如台风。风速突然增加到正常风速的两倍或三倍，然后在这样的阵风中在几秒钟内逐渐减弱。然而，在任何假定风在相当长的时间内保持稳定的国家的实践守则中，都没有对这种突然的阵风荷载进行描述。本研究主要从以下两个角度通过风洞试验来研究突发性阵风对房屋风荷载的影响：1)模拟风洞中的突发性阵风；2)为了阐明阵风引起的风荷载的机理。为了模拟阵风，我们在远离平顶房屋模型的位置设置了栅栏。通过调整栅栏的高度和与模型的距离，可以产生突然的阵风，这与自然风中的阵风非常相似。屋面流动受影响较大，屋面风荷载通过阵风发生突变。分离的剪切层被阵风扫过，在屋顶的边缘产生了非常严重的局部吸力。在斜流的情况下，由于风速的突然增大和风向的变化，在短时间内在屋顶和襟翼上形成了圆锥形的旋涡。