Study on Wind Resistance performance of Roof Tiles in Strong Wind

在上一份报告（项目编号13640643）中阐明了屋顶瓦片在不提升的情况下的风力特征。但是瓦片在被强风吹走之前就被掀起来了。因此，必须明确有升力的瓦片上的风力特性，因为它们可能不同于没有升力的瓦片上的风力特性。考虑到瓦片在强风中的行为，瓦片提升值与风力之间的关系也需要明确。首先，通过在自然风中的全尺寸测量来测量作用在人工提升的瓦片上的风压和力。结果表明：（1）屋面一般部位的瓦片平均风荷载随瓦片起升量的增加而增大，并趋于负值。在另一区域，平均风力随瓦片抬升的变化可以忽略不计。2)最大负峰值力随瓦片提升的增加是由屋顶一般部分的内部压力变化引起的。对于边缘中的瓷砖，随着瓷砖提升而增加的负峰值力是由外部压力的变化引起的。3)瓦面内压随提升的波动一般可通过对每一侧整个屋面的外压进行空间平均来估算。但是，在再附流通过差距吹向瓦下空间的区域内，内压受到局部外压的强烈影响。其次，通过风洞试验详细探讨了屋盖上的风力分布。并根据风洞试验结果确定了静载试验的载荷分布模式，最后通过静载试验，明确了风力与瓦的起升值之间的关系。

The characteristics of wind forces on roof tiles without lifting were clarified in the previous report (Project number 13640643). But tiles are lifted just before they are dislodged in strong wind. Therefore the characteristics of wind force on tiles with lifting must be clarified because they are probably different from these on tiles without lifting. Considering the behavior of tiles in strong wind, the relationship between the tile lifting value and the wind force should be also clarified.This study carried out examinations described as follows. First, the wind pressure and force acting on artificially lifted tiles were measured by the full-scale measurement in a natural wind. The result derived followings : 1)Mean wind force on tiles in general parts of roof increases to negative as tile lifting increases. In the other area, the change of mean wind force with tile lifting is negligible. 2)The increase in maximum negative peak force with tile lifting is caused by a change in internal pressure in general parts of the roof. For tiles in the verge, the increase in negative peak force with tile lifting is caused by a change in external pressure. 3)The internal pressure fluctuation of tile with lifting could be generally estimated by spatially averaging the external pressures through the whole roof of each side. But the internal pressure is strongly affected by the local external pressure in a area where the re-attached flow blows into the space under the tiles through the gap.Next, wind force distributions on roof were probed by wind tunnel tests in detail. And loading distribution patterns for static loading test were determined according to the result of the wind tunnel test.Finally, the relationship between the wind force and lifting value of tiles were clarified by the static loading test.