Effect of inclined self-tapping screws connecting laminated veneer lumber on the shear resistance

Abstract

The load-bearing capacity and bearing stiffness formula of pin connectors in the current standard Eurocode 5 does not consider the influence of the angle on the single shear connection, especially for inclined screws connecting laminated veneer lumber (LVL). Therefore, research was conducted into the influence of the angle and friction on the load-bearing capacity and bearing stiffness of self-tapping screws connecting LVL made from Douglas fir. This study analyzed the existing calculation model of bearing capacity and stiffness and then derived a model with friction. The results showed that the load-bearing capacity and bearing stiffness in the tensile-shear mode was better than in the compression-shear mode, and that it was better with a 45° to 60° self-tapping screw angle. The lateral support can remarkably improve the bearing capacity and bearing stiffness in the compression-shear mode. The theoretical calculation formula for self-tapping screws connecting solid wood can better reflect the bearing capacity of inclined screws connecting LVL in the tensile-shear stress mode after increasing the fitting coefficient to 1.25. The safety factor was approximately 0.97 to 1.19. The proposed models in this paper are suitable for situations with friction in the compression-shear mode.