Effects of Intersection Angle on the Nail-holding Performances of Pinus massoniana and Cunninghamia lanceolata Dimension Lumber

Abstract

Self-tapping screws and round steel nails were driven into Pinus massoniana and Cunninghamia lanceolata dimension lumber pieces to explore the influence of intersection angle on nail-holding performance, expecting to provide a more complete scientific basis for the connection of wood structures. The results showed that (1) as the intersection angle declined, the nail-holding strength of self-tapping screws for both P. massoniana and C. lanceolata dimension lumber gradually decreased. At the intersection angle of 90°, nail-holding strength was the maximum, being 79.8 and 80.5 N/mm, respectively; (2) With the reduction of the intersection angle, the nail-holding strength of round steel nails for both dimension lumber initially increased and then gradually declined. The maximum nail-holding strength (21.0 N/mm) of P. massoniana appeared at the intersection angle of 45° while that (22.3 N/mm) of C. lanceolata appeared at 60°; (3) No matter for self-tapping screws or round steel nails, the rigidity at the connection point was the greatest at the intersection angles of 90° and 0° (cross-section). If diagonally nailed into lumber, both self-tapping screws and round steel nails can enhance the ductility of connection joints, where the former exerts a more evident effect.