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

本研究旨在搜集任意形状单层网壳的屈曲强度和极限强度资料。2002年和2003年的研究结果概要如下。单层网壳的形状优化是以最大线性屈曲荷载和最小指定构件之间的最大和最小长度差为目标进行的。结果表明，在考虑线性屈曲荷载的情况下，得到了几种杆长下的最优形状。采用张量积Bezier曲面对网壳进行建模，得到了网壳的光滑优化外形，并对HP网壳进行了静力弹塑性屈曲分析。HP网壳是一个具有负高斯曲率的曲面。将初始屈服荷载和极限荷载用柱屈曲强度表示，并将其应用于高压网壳的初始屈服荷载和极限荷载的估算。通过对单层网壳结构的地震反应和动力屈曲性能的研究，分析了加载缺陷和几何初始缺陷对网壳结构动力屈曲性能的影响。反应谱分析采用CQC（完全二次组合）法。计算了结构在水平地震作用下的反应加速度。在此基础上，提出了网壳结构的地震静力荷载。在动力屈曲分析中，采用阶跃波和单脉冲波作为输入波形，分析方法为时程非线性响应分析。研究了穹顶半对角和输入方向对动力屈曲性能的影响。

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.