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

通过用螺钉固定尺寸为2- 3cm厚和10-20 cm宽的弯曲的堆叠木板而获得的弯曲壳结构作为木材结构方法具有许多优点。因为它可以以很低的成本实现一个覆盖大面积的巨大穹顶。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。本文采用云杉长200- 450 cm、厚2-3 mm的薄板模型试验和数值分析相结合的方法，对该结构的强度特性和变形特性进行了研究。这些木板的两端都固定在销支撑上，一个支撑固定在滑动底座上，以便能够通过测压元件测量水平力。本文研究了三种结构类型：1）简单的木板堆叠，2）奇数层的纵向木板，但网格点处的交叉构件具有偶数层，3）填充 ...更多信息 通过间隔物来艾德差距化第二结构的间隙。模型结构用小螺栓固定在网格点上，并检查了从一层到五层的结构。从该实验中，证明了弯曲堆叠板结构与作为整体的结构相比，对于三层结构和五层结构分别仅显示75%和38%的刚度。结构类型3比结构类型2具有更大的优势，即在没有空间填充构件的情况下，这种薄板结构会发生屈曲现象，有限元法对壳体结构进行应力分析是常用的方法，但对于这种材料制成的受自重弯曲的曲梁，用常规有限元法进行受力分析是很困难的。在这里，我们开发了一个新的有限元程序，牛顿-Lapson的方法，考虑到几何非线性效应。计算结果与试验结果吻合较好，如荷载-挠度曲线、挠度形状和弯矩分布等。因此，很明显，这种技术是非常有前途的螺旋弯曲堆叠板结构的分析。少

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