Abstract
Recently, in Japan, cross laminated timber (CLT) has been attracting attention as a structural material. Based on this, more test data are required on CLT consisting of Japanese wood species. CLT consists of several layers of lumber that are laminated by the gluing of longitudinal and transverse layers; therefore, their strength properties are
influenced by the load direction, the direction of lumber, the grade of lumber, and layups. In this study, we prepared CLT specimens (symmetrical composition, 3-layer 3-ply, 3-layer 4-ply, 5-layer 5-ply, 5-layer 7-ply, and 7-layer 7-ply layups, and the Mx60 strength grade according to the Japanese Agricultural Standard for CLT) consisting of sugi
(Cryptomeria japonica) finger jointed lumber (width 105 mm and thickness 30 mm), and conducted the bending tests under in-plane loading. The results were as follows: (1) Layers loaded parallel to the grain are mainly effective for the bending Young’s modulus and bending strength of CLT panels under in-plane loading. (2) Bending Young’s modulus and bending strength of CLT panels under in-plane loading can be estimated from those of lumber and number of layers loaded parallel to the grain. (3) Bending Young’s modulus of CLT panels under in-plane loading can be measured by dynamic testing. (4) Bending Young’s modulus and bending strength of CLT panels under in-plane loading are strongly correlated. (5) Finger joints in lumber in the longitudinal direction on the tension side between loading points play a significant role in specimen failure.
