Bending performance of sugi cross-laminated timber (CLT) composed of different thickness laminae

Abstract This study aims to examine the influence of lamina thickness on the bending performance of sugi cross-laminated timber (CLT). The lamina specimens measuring 20 mm, 30 mm and 40 mm thick × 115 mm wide, and the CLT specimens composed of 5-layer–5-ply of equally thick laminae with 20 mm-, 30 mm- and 40 mm-thick laminae, respectively, and 3-layer–3-ply with 40 mm-thick laminae for the outer layers and 20 mm-thick laminae for the inner layer were prepared. The Young’s modulus and shear modulus were measured by dynamic methods. The bending tests were conducted and the bending performances such as apparent bending Young’s modulus and bending strength were measured, and the failure behavior was observed. The results showed that the influence of lamina thickness on the bending strength and failure behavior of CLT was not clear. On the other hand, the shear modulus of the CLT specimens composed of 40 mm-thick laminae whose width-to-thickness ratio of the lamina in the transverse layer was less than 3.5 was small, indicating that the small width-to-thickness ratio of the lamina in the transverse layer influenced bending performance. Furthermore, it was considered that the bending Young’s modulus and bending strength of the CLT specimens could generally be estimated using the bending Young’s modulus and bending strength of the laminae specimens by composite theory under the conditions in this study.