Estimations of Buckling Strength and Ultimate Strength of Single Layer Lattice Shells

本研究旨在收集任意形状单层网壳的屈曲强度和极限强度数据。对单层网壳结构进行了形状优化，使其线性屈曲载荷最大，最大长度与最小长度之差最小。结果表明，在考虑线性屈曲荷载的情况下，得到了杆件长度较少的最优形状。利用张量积Bezier曲面对网壳进行建模，可以得到光滑的最优形状。采用静态弹塑性屈曲分析方法，研究了双曲抛物面网壳在均布载荷作用下的屈曲行为。HP网格壳是一种具有负Gauss曲率的曲面。将初始屈服荷载和极限荷载表示为柱的屈曲强度，并将该概念应用于高压网壳的初始屈服荷载和极限荷载的估算。此外，明确了荷载缺陷和几何初始缺陷对屈曲行为的影响，并对单层穹顶网壳进行了地震响应分析和动力屈曲分析。反应谱分析采用完全二次组合(CQC)法。计算了结构在水平地震作用下的响应加速度。在此基础上，提出了网壳结构的静力地震荷载建议。在动力屈曲分析中，采用阶跃波和单脉冲波作为输入波形，采用时程非线性响应分析方法进行分析。考察了穹顶半对角和输入方向对动力屈曲行为的影响。

This study is projected for the purpose of collecting of the data on buckling strength and ultimate strength of single layer lattice shells with optional shapes. The outlines for the research results in 2002 and 2003 are shown below.Shape optimizations of single layer lattice shells were carried out for maximizing the linear buckling load and minimizing the difference between the maximum and minimum lengths among the specified members. As a result, while taking the linear buckling loads into consideration, the optimal shapes with few kind of member length were obtained. Smooth optimal shapes could be obtained by modeling the lattice shells using tensor product Bezier surface.The buckling behavior of HP (Hyperbolic Paraboloidal) lattice shells under uniform loadings was examined using the static elasto-plastic buckling analysis. HP lattice shell is a surface with a negative Gauss curvature. The initial yield load and the ultimate load were expressed in terms of column buckling strength, and the concept was applied to estimate the initial yield load and the ultimate load of HP lattice shells. In addition, the effects of loading imperfection and geometrical initial imperfection on the buckling behavior were made clear.On the single layer lattice shells with dome shape, the earthquake response behavior and the dynamic buckling behavior were examined. The CQC (Complete Quadratic Combination) method of response spectrum analysis was used. The response acceleration subjected to horizontal earthquake motions were evaluated. Based on the result, the static earthquake load for lattice dome was proposed. On the dynamic buckling analysis, the step wave and single pulse wave were adopted as input waveforms, the analysis method was the time history non-linear response analysis. The effects of the half subtended angle of the dome and the input direction on the dynamic buckling behavior were examined.