单层球面网壳结构屋面雪荷载最不利布置研究
RESEARCH ON THE MOST DANGEROUS SNOW DISTRIBUTION ON SINGLE-LAYER SPHERICAL LATTICED SHELLS
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摘要: 雪荷载对大跨网壳结构的影响相对较大, 而且由于风及温度等的作用, 雪荷载在屋面的分布往往是不均匀的, 确定雪荷载的最不利布置是保证大跨网壳结构安全设计需要考虑的问题。该文提出了一种分区组合法来确定单层球面网壳结构在屋面雪荷载作用下的最不利布置, 该方法首先将屋面沿径向分为8个扇区, 分别考虑雪荷载布置在不同扇区的排列组合, 计算结构的极限承载力, 确定雪荷载的径向最不利布置, 然后再将屋面按环向分为6个环区, 计算并确定雪荷载环向最不利布置, 最后组合径向和环向两种情况, 确定单层球面网壳结构雪荷载的最不利布置。研究结果表明, 当雪荷载布置在半跨并且是最外两环时, 结构的极限承载力最低, 比满跨和半跨雪荷载工况分别降低24.8%和16.3%。Abstract: Snow loads are important in the design of large span latticed shell structures, and the distribution of snow on roof is non-uniform due to the effect of wind and temperature. Thusly, the problem how to determine the most dangerous snow distribution on single-layer spherical latticed shells is valuable. A method of location combination is provided in this paper to solve the above problem. In first step, the roof is divided into 8 sectors in the radial direction and snow loads are applied at different sectors considering all kinds of permutations and combinations, then the limited bearing capacity of the latticed shell was calculated and the most dangerous snow distribution in the radial direction was determined. In second step, the roof is divided into 6 locations in the circular direction and snow loads are applied at different locations considering all kinds of permutations and combinations, then the limited bearing capacity of the latticed shell was calculated and the most dangerous snow distribution in the circular direction was determined. In third step, the dangerous snow distributions in the radical and in the circular direction are combined together and the most dangerous snow distribution on spherical latticed shells can be determined. Results show that when the snow loads are applied at the outer two circles in the half-span roof, the limited bearing capacity of the latticed shell is lowest, which decreased 24.8% and 16.3% compared with full-span and half-span snow loads respectively.