基于风洞试验的不同坡度多跨锯齿屋面风压特性研究

多跨锯齿屋面因其具有跨度大、结构轻盈的特点成为典型的风灾易损结构。目前国内规范对锯齿屋盖的风荷载规定较为粗略,简单给定了统一的风压系数参考值,在实际工程应用中具有一定的局限性。本文以某4跨锯齿房屋为研究对象,通过风洞试验测试了15°、21°、26°、30°和40°等5种不同屋面坡度对锯齿屋盖风压特性的影响。试验结果表明,我国建筑结构荷载规范GB 50009-2012关于锯齿屋面的负风压系数绝对值明显偏小,锯齿屋面最不利均面积负风压系数随着坡度的增加逐渐从高屋角(HC)区转移到屋面边区(SE),且与HC区相反,SE区内的最不利负风压系数绝对值随角度增加而增大;锯齿中间B、C跨最不利均面积负风压系数始终出现在HE区,其绝对值随角度增加而增大,而尾跨D则出现在SE区,且随角度增加而减小;屋面最不利极值负风压系数为-9.6,随着屋面坡度的增大,屋面的最大极值负风压系数绝对值逐渐减小。此外,以各坡度屋面负风压系数的分布为依据,给出了不同屋面坡度范围和不同跨屋面风压系数分区划分建议。

Wind pressure characteristics of multi-span saw-tooth roof with different slopes based on wind tunnel test

Because of its large span and light structure,multi-span saw-tooth roof becomes a typical vulnerable structure in wind disaster.At present,the wind load of saw-tooth roof in the domestic code is relatively rough,and a unified wind pressure reference value is simply given,which has certain limitations in practical engineering applications.In this work,taking a 4-span saw-tooth roof as the research object,the influence of 5 roof slopes on the wind pressure characteristics of saw-tooth roof is tested by wind tunnel test.The test results show that the absolute value of the negative wind pressure coefficient of saw-tooth roof is obviously small,and the negative wind pressure coefficient of the most unfavorable average area of saw-tooth roof is gradually transferred from the high angle(HC)area to the roof side area(SE)with the increase of slope,and the absolute value of the most unfavorable negative wind pressure coefficient in SE area is increased with the increase of angle.The most unfavorable mean area negative wind pressure coefficient of B and C spans in the middle of saw-tooth always appears in HE area,and its absolute value increases with the increase of angle;while the last D span appears in SE area,and decreases with the increase of angle.The most unfavorable extreme negative wind pressure coefficient of the roof is-9.6.With the increase of the roof slope,the absolute value of the maximum extreme negative wind pressure coefficient of the roof gradually decreases.Based on the distribution of the negative wind pressure coefficient of the roofs with different slopes,some suggestions are given for the division of wind pressure zones in different roof slope ranges and across roofs.