雪荷载规范比较与风致雪漂移风洞试验方法研究

CODES COMPARISON AND WIND TUNNEL SIMULATION OF WIND-INDUCED SNOWDRIFT

风致雪飘移在复杂屋面上产生的不均匀雪荷载是多雪地区结构设计中需要重点考虑的问题之一。该研究对比了我国和美国、加拿大、欧洲四本关于雪荷载的规范,比较了雪荷载的计算表达式、屋面形式等内容,通过风洞试验,采用食用盐、硅砂、明矾、干松木屑等材料,对雪飘移问题进行了试验研究。结果发现:四本规范中都是将基本雪压与各种系数的乘积作为雪荷载;相对其他三本规范,我国规范对影响雪荷载的各种环境参数考虑相对较少;明矾因为颗粒间作用力较大,在风洞试验中不易产生连续的漂移运动;干松木屑因为密度太小,模拟效果也不佳;大密度的食用盐颗粒和硅砂的模拟效果相对较好;为了在实际工程中应用风洞试验的方法,需要进行多参数的现场观测、收集完整的气象资料、研究试验的相似关系和试验参数。

The non-uniform snow load on a complex roof is one of the most important factors that should be considered by a designer. The snow codes of China, America, Canada and Europe were compared, and the difference of equations and roof types were analyzed. Snowdrift simulation was carried out by using edible salt, silica sand, alum and dry sawdust of pine in a wind tunnel. The results show that in the four codes, snow loading is expressed by the product of reference snow pressure and coefficients in different types, and that fewer parameters on environment are considered in Chinese code, compared with other codes. As the adhesive force of alum is too strong, it is difficult to produce a continuous drift motion in a wind tunnel test for this material. The simulation effect of the dry sawdust of pine is not as good as its density is too small. The edible salt and silica sand with high density have relatively good simulation effects. In order to attain non-uniform snow loading on a structure in a design period by wind tunnel tests, the field observation with multiply parameters, the collection of meteorological data in detail, similarity criterion and parameter selection research are necessary as a basic research.