Study on Ultimate Strength of Single-Layer Latticed Domes

本研究的目的是研究几何缺陷和荷载条件对单层网壳结构极限强度的影响。为了研究无几何初始缺陷穹顶的基本弹塑性屈曲行为，进行了弹塑性分析。其次，研究了具有几何初始缺陷的穹顶结构的屈曲行为。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附加集中荷载。结果表明，附加荷载和初始缺陷的存在大大降低了穹顶的屈曲荷载。主要研究结果如下：1.用穹顶的长细比来估算刚接单层网壳的弹塑性屈曲性能。对于没有几何初始缺陷的穹顶，对于IS&lt；0.80的穹顶，弹塑性屈曲荷载小于弹性屈曲荷载，这些穹顶通过一般屈曲而倒塌。对于具有0.80&lt；ls&lt；1.0的穹顶，穹顶由于节点屈曲而发生倒塌。对于具有几何初始缺陷的穹顶，随着ls值的增大，弹塑性屈曲载荷减小。尤其是由于节点屈曲而倒塌的穹顶结构，其弹塑性屈曲荷载受几何初始缺陷的影响较大。弹塑性屈曲载荷的估算采用修正的Dunkerley公式作为Lambdas和Lambda的函数。

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.