Effects of Growth Ring Width, Height from Tree Base, and Loading Direction on Transverse Compression of Plantation Japanese Larch Wood

This study aimed to investigate the effects of growth ring width, height from the tree base, and loading direction on the transverse compressive strength of Japanese larch wood, which is commonly used in wood structures in China. Plantation wood is often used to replace natural forest woods for reconstruction purposes, despite significant differences in properties (e.g., growth rings, density, strength) between them. The ends of transversely compressed wood members in such structures are prone to damage by breaking or crushing. A transverse compressive test was conducted following Chinese national standards, which revealed the following key findings. (1) There was a significant difference in the transverse compressive strength of wood with different growth ring widths (p < 0.05). The radial and slant compressive strength of wood increases with growth ring width, while the tangential compressive strength decreases as growth ring width increases. (2) The transverse compressive strength of wood decreases as the height from the tree base increases. The radial, tangential, and slant compressive strength at a lower height were 18.39%, 22.58%, and 18% higher than those at a greater height in the stem, respectively, with significant differences at the 0.05 level. (3) The load-displacement curve of Japanese larch wood under radial and slant compression follows a "three-segment" form. In contrast, the load-displacement curve of tangential compression is a continuous curve that drops sharply upon reaching its highest point. (4) There is a significant difference in the transverse compressive strength of Japanese larch wood in different loading directions when growth ring width and height from the tree base are constant (p < 0.05), which fall into order as tangential > radial > slant.