中外荷载规范雪荷载取值及控制影响因素对比分析

基于对当今中外荷载规范雪荷载章节的梳理,以雪荷载对应取值及控制因素的差异为视角进行了深入的对比剖析,得出各国规范体系构架存在较高相似性,均采用由地面雪荷载（基本雪压）乘上一系列用以量化计算的控制因素系数而获得屋面雪荷载值,而屋面雪荷载按作用效应又可划分为基本雪荷载、漂移雪荷载与滑落雪荷载三类,且各类别在不同规范中取值具有差别。由此建议在中国新版建筑荷载规范雪荷载章节继承完善基本雪荷载和漂移雪荷载,并补充对屋面滑落雪荷载取值规定。另外,总结了各国规范中雪荷载控制影响因素,可归为外界环境与建筑本身两大类,并依据国外规范对控制因素的考虑权重,选取影响较大且我国规范尚未考虑的因素进行详细探讨。由此建议引入考虑降雨量与坡屋顶特性的雨雪联合因素,考虑宏观地貌气候与周围环境的建筑暴露状态因素,考虑室内采暖温度与屋面热阻的建筑采暖因素及考虑屋面光滑程度的屋面材料因素,以达到优化规范体系构架的目的。

Contrastive analysis of snow load value and influence factors among Chinese and foreign building load codes

Based on a review of recent building load codes, a comparative analysis of the values of snow load of the existing codes and the corresponding controlled factors were conducted in this paper in order to identify deficiencies for improvement. The comparative results show that the systematic frameworks of the codes in different countries are similar. They all adopts the ground snow loads (basic snow pressure) multiplied by a series of controlled factor coefficients for the roof snow loads, while the latter can be divided into three categories as basic one, drift one and slide one; different codes adopt different values of these three categories. Therefore, it is suggested that in the development of next generation of Chinese load code for the design of building structures, the basic and drift roof snow loads should be inherited and improved while the slide one should be added.Besides, the corresponding controlled factors can be classified into two categories as the external environment and the building itself by summarizing different load codes. The controlled factors which have high influence but have not been considered in the Chinese code are then discussed based on the statistical weight of them in the foreign codes. As a result, the following factors are proposed in this paper to achieve the goal of systematic framework optimization of the snow load for the development of the next generation of the Chinese load code for the design of building structures: the rain-on-snow factor which considers the characteristics of rainfall and slope roofs, the exposure factor which considers the marco landform climate and meso building surrounding, the thermal factors which considers the building heated temperature and roof thermal resistance, and the material factor which considers the smoothness of roof.