Study on Ultimate Strength of Single-Layer Latticed Domes

本研究旨在探讨单层球面网壳在几何缺陷及荷载条件影响下的极限承载力。为了研究无初始几何缺陷的穹顶的弹塑性屈曲性能，进行了弹塑性分析。其次，研究了具有初始几何缺陷的穹顶的屈曲性能。然后进行了跨度为4.6m的模型试验。荷载类型有集中荷载、单侧均布荷载和均布荷载加集中荷载。结果表明，由于附加荷载和初始缺陷的存在，穹顶的屈曲荷载大大降低。所得结果可概括如下：刚接单层网壳的弹塑性屈曲性能可由网壳的长伸比来估计。对于无初始几何缺陷的穹顶，当初始几何缺陷小于0.80时，弹塑性屈曲荷载小于弹性屈曲荷载，这些穹顶均以一般屈曲形式破坏。对于0.80 < ls < 1.0的穹顶，穹顶因节点屈曲而倒塌。对于具有初始几何缺陷的穹顶，随着ls值的增大，弹塑性屈曲荷载减小。特别是初始几何缺陷对因节点失稳而倒塌的穹顶的弹塑性失稳荷载有很大影响。采用修正的Dunkerley公式作为λ的函数和λ的函数来估计弹塑性屈曲载荷。

The purpose of this study is to investigate the ultimate strength of single-layer latticed domes under the influence of the geometrical imperfections and loading conditions. To examine the fundamental elasto-plastic buckling behavior of the dome without geometrical initial imperfections, the elasto-plastic analysis is carried out. Next, the buckling behavior of the domes with geometrical initial imperfections is examined. Then we carried out the model experiment of span 4.6m. Loading types are concentrated load, one-side uniform load and uniform load with additional concentrated load. As a result, the buckling load of the domes reduced considerably by the existence of the additional load and the initial imperfections. Summaries of the results obtained may be as follows.The elasto-plastic buckling behavior of the rigidly jointed single-layer latticed dome is estimated by the slenderness ratio of the dome lambdas. For the domes without geometrical initial imperfections, for the domes with is <0.80, the elasto-plastic buckling load is smaller than the elastic buckling load, And these domes are collapsed by general buckling. For the domes with 0.80 < ls < 1.0, the domes are collapsed by node buckling. For the domes with geometrical initial imperfections, as the value of ls increases, the elasto-plastic buckling load decreases. Especially, the elasto-plastic buckling load of the dome which is collapsed by node buckling is greatly influenced by geometrical initial imperfections. The elasto-plastic buckling load is estimated by using Modified Dunkerley Formulation as the function of lambdas as well as the function of LAMBDA.