Role of timber pegs in reinforcing stop-splayed scarf joints

The effectiveness of an all-timber solution, based on the uses of timber pegs, to reinforce stop-splayed scarf joints with transverse key has been investigated in this paper. An experimental program on unreinforced and timber pegged reinforced scarf joints subjected to tensile loadings has been carried out. Two timber pegs made with ash, and having a diameter equal to 20 mm, have been used as fasteners to reinforce the scarf joints. The experimental outcomes have been analysed and critically discussed, focusing on the role of timber pegs in reinforcing scarf joints. Three fundamental aspects have been investigated: load-bearing capacity, ductility and influence of slenderness ratio (between thickness of members and diameter of the peg) due to the introduction of timber pegs. Test results showed that timber pegs provide adequate robustness to the connections because they modified both force-displacement constitutive behavior (increasing load-bearing capacity, stiffness and ductility) and failure mechanisms from brittle to ductile. It has been also proved that greatest slenderness ratios are effective in enhancing the ductility of the connections; thus, at the same thickness of members, pegs with reduced diameters could be preferred in reinforcing scarf joints. From testing, important findings on the qualitative behavior of scarf joints reinforced by timber pegs are emerged, but the reduced number of specimens did not allow conclusive considerations and future investigations will be necessary to support the obtained results.