Reinforcement of dowel-type timber joints with self-tapping screws

Abstract

This paper addresses the assessment of timber-to-timber dowel-type joints in double shear, reinforced with self-tapping screws (STS). This type of joint is known to be less prone to brittle failure as the screws tend to increase the embedding strength while preventing premature splitting. This theory was tested through an experimental campaign carried out for joints of maritime pine (Pinus pinaster Ait.) and Scots pine (P. sylvestris L.). Monotonic and cyclic tests were performed, with and without reinforcement, and the results were analysed. The results highlight the effectiveness of the reinforcement in preventing premature splitting while increasing the capacity of the joints to sustain higher displacements. The contribution of STS was more evident in the fully reversed cyclic tests, where the reinforcement played a crucial role in increasing the ductility and energy dissipation. The use of STS, perpendicular to the dowel, allows the reinforcement of dowelled joints with insufficient end distances.