Study on the strength of glued laminated timber beams with round holes: difference in structural performance between homogeneous-grade and heterogeneous-grade timber
Study on the strength of glued laminated timber beams with round holes: difference in structural performance between homogeneous-grade and heterogeneous-grade timber
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DOI：
10.1186/s10086-021-01941-3
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发表时间：
2021-01-19
影响因子：
2.9
通讯作者：
Inayama, Masahiro
中科院分区：
文献类型：
--
作者：
Okamoto, Shigefumi;Akiyama, Nobuhiko;Inayama, Masahiro
假设整根胶合木梁均为普通木材，对带圆孔胶合木梁提出了各种设计规范和设计建议。然而，在日本，胶合板组成的木材木材的木材是很少用于梁。在这项研究中，在胶合板层合梁的承载能力的差异，由不同等级的木材和非均匀等级的木材与圆孔时，由开裂断裂进行了实验和分析研究。测试中使用的材料是胶合层压梁，由强度等级为E105-F345的高等级苏格兰松木和强度等级为E105-F300的高等级苏格兰松木组成。试验证实，尽管由非均质级木材组成的胶合板梁在带孔层中具有较低的材料强度，但其抗因与孔相关的裂纹而引起的断裂的能力与由均质级木材组成的胶合板梁几乎相同。作用在孔小于梁高的一半的层压木材的孔的应力低于在胶合板组成的非均质级木材的胶合板组成的梁比在胶合板组成的非均质级木材。应力的比值被发现近似等于作用在内层薄板上的最大弯曲应力或最大剪应力的比值，如由Bernoulli-Euler理论确定的。
Various design codes and design proposals have been proposed for glued laminated timber beams with round holes, assuming that the entire beam is composed of homogeneous-grade timber. However, in Japan, glued laminated timber composed of homogeneous-grade timber is rarely used for beams. In this study, the difference in the load-bearing capacity of glued laminated beams composed of homogeneous-grade timber and heterogeneous-grade timber with round holes when fractured by cracking was investigated experimentally and analytically. The materials used in the tests were glued laminated beams composed of homogeneous-grade Scots pine timber with a strength grade of E105-F345 and heterogeneous-grade Scots pine timber with a strength grade of E105-F300. Experiments confirmed that although the glued laminated beams composed of heterogeneous-grade timber have a lower material strength in the lamina with holes, its resistance to fracturing due to cracks associated with the holes is almost the same as that of the glued laminated beams composed of homogeneous-grade timber. The stresses acting on the holes in the laminated timber with holes of less than half the beam height were lower in the glued laminated beams composed of heterogeneous-grade timber than in the glued laminated beams composed of homogeneous-grade timber. The ratio of the stresses was found to be approximately equal to the ratio of the maximum bending stress or the maximum shear stress acting on the inner layer lamina, as determined by Bernoulli-Euler theory.