Mechanical performances of finger jointed cross laminated timber (CLT)

Based on the idea of first producing small-size CLT panels and afterward connecting them using finger joints to make larger CLT panels, finger-jointed CLT test specimens were fabricated by setting experimental parameters such as the kind of finger joint (large or normal), the combination of finger joint strength (strong-strong, or weak-weak) and the number of layers, and ply (3L3P, 5L5P, and 5L7P). Destructive tests subjected to out-of-plane as well as in-plane bending and shear, and axial compression load were performed. To judge the mechanical performance of the finger-jointed CLT panels, the lower 5% strength value evaluated from the destructive tests data were used for comparison with the characteristic strength value of CLT products assigned by the Ministry of Land, Infrastructure, Transport and Tourism in Japan (MLIT). On the other hand, the lower 50% stiffness value evaluated from the destructive test data was used for comparison with the design stiffness values proposed by commercial sectors. Most of the tested finger-jointed CLT groups satisfied the requirements for the characteristic strength values although there were a few exceptional cases in the weak-weak groups. All of the tested finger jointed CLT groups satisfied the proposed design stiffness values.