Basic study on the strength estimation of curved stacked plank structures with screw fixation

螺钉固定弯曲叠板结构强度估算的基础研究

• 批准号: 13460073
• 负责人: OHTA Masamitsu
• 金额: $ 8.7万
• 依托单位: UNIVERSITY OF TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13460073/
• 关键词: thin wood board; screwed planks; curved stacked plank structure; shell structure; geometrical non-linearity; finite elements method; Newton-Lapson's method; 変形挙動; 大変形

The curving shell structures, which are obtained by fixing the curved stacked planks sized 2-3 cm thickness and 10-20 cm width with screws, have many advantages as a timber structuring method. Because it can realize a huge dome that covers a large area by very low cost. Though, there are many uncertainties in its strength performances from the view points of the structural design. In this research, the strength nature and deformation behavior of this structure were studied using scale model experiments and a numerical analysis method.In the model experiments, long thin planks of spruce sized 200-450cm long and 2-3 mm thickness were used. Both ends of these planks were fixed to pin supports, and one support was hold on a sliding base to enable the measurement of the horizontal force by a load-cell. Three types of structure were examined here : 1) simple stacking of planks, 2) longitudinal planks with odd number layers, but crossing members at grid points with even number layers, 3) fill … More ed the gap of the second structure by spacers. Model structures were fixed at the grid points with small bolts, and from one to five layer structures were examined. From this experiments, it was proved that the curved stacked plank structure shows only 75% and 38% rigidity, for three layer structure and five layer structure, respectively, compared with the structure as an unity. The structure type 3 has much advantage to type 2 structure, which means that there occurs buckling phenomenon without space filling members for such a thin planks.It is common to use the Finite Element Method (FEM) to the stress analysis of the shell structure, but it is very difficult to realize the loading analysis on the curved beams made of such a material that is bent by the self-weight by an ordinal FEM. Here, we developed a new FEM program, with Newton-Lapson's method, that takes account the geometrical non-linear effects. Analysis by this program showed good agreement with experimental results such as the load-deflection curve, the deflection shape and bending moment distribution. Thus, it became clear that this technique was very promising for the analysis of the screwed curved stacked-planks structure. Less

曲壳结构是将厚度为2~3 cm、宽度为10~20 cm的曲板用螺丝固定而成，作为一种木结构形式，具有许多优点。因为它可以以非常低的成本实现一个占地面积很大的巨型穹顶。然而，从结构设计的角度来看，其强度性能存在许多不确定性。本研究采用缩尺模型试验和数值分析方法，对该结构的强度特性和变形性能进行了研究。这些木板的两端都固定在销式支座上，其中一个支座固定在滑动底座上，以便能够通过称重传感器测量水平力。这里研究了三种结构：1)简单的木板堆叠，2)具有奇数层的纵向木板，但具有偶数层的网格点的交叉杆件，3)填充…第二个结构的空隙更多地被间隔物填满。模型结构用小螺栓固定在网格点上，从一层到五层结构进行了检查。试验结果表明，与整体结构相比，三层结构和五层结构的弯曲叠合板结构的刚度分别只有75%和38%。结构类型3相对于类型2结构有很大的优势，这意味着对于这样的薄板，在没有空间填充构件的情况下会发生屈曲现象，通常使用有限元方法对壳体结构进行应力分析，但用顺序有限元方法很难实现对自重弯曲的曲梁进行载荷分析。在这里，我们开发了一个新的有限元程序，采用牛顿-拉普森方法，考虑了几何非线性效应。用该程序分析得到的荷载-挠度曲线、挠度形状和弯矩分布等结果与试验结果吻合较好。因此，很明显，这种技术对于分析螺旋曲线板结构是非常有前途的。较少