Shear performance of tongue-and-groove joints for CLT

Abstract

This paper presents an experimental study on tongue-and-groove (T&G) and half-lap (HL) joints for 5-layer cross-laminated timber (CLT) connected with self-tapping screws (STS). A total of 54 monotonic and cyclic loading tests were carried out for vertically screwed T&G and HL joints, the load-carrying capacity, stiffness, ductility, strength impairment and energy dissipation of the joints have been investigated. The results showed that the load-carrying capacity, stiffness and ductile ratio of T&G joints were higher than those of HL joints. Besides, joints with 8 mm diameter STS had higher load-carrying capacity, initial stiffness and ductility than those with 6 mm diameter STS. Fully-threaded (FT) STS could improve the loading-carrying capacity of the joints compared with partially-threaded (PT) STS, however, the stiffness and ductility were not as good as the latter. Under cyclic loading, the strength impairment rate of T&G joints was lower than that of HL joint, and the energy dissipation of T&G joints was better when the displacement was small. Two prediction models presented in this paper were conservative compared with the experimental values. The results presented in this paper can provide fundamental basis for supporting the potential engineering application of CLT panels connected with T&G joints.