Shear performance of beech dowel rotary welded SPF substrate joints with different structure dimensions

Objective This study aims to clarify the influence of structure dimensions on the shear performance of wood dowel rotary welding joints and explore group effect of the joints.

Method This paper investigates the influence of end distance, spacing distance and row distance on the shear performance of joints using a beech (Fagus sylvatic) dowel rotary welded SPF (spruce-pine-fir) substrate in a single shear test, and the shear performance of single dowel and double dowel joints with different diameters.

Result Shear performance of joints is mainly dependent on the end distance and spacing distance, with the influence of row distance being small. The dominant failure mode was wood dowel shear. However, when the end distance was less than or equal to 4d (d is the wood dowel diameter after welding) and spacing was less than or equal to 3d, block shear and cracking occurred in the substrate, substantially reducing the shear performance. The joint peak load increased first and then decreased as the end distance, spacing distance, and row distance dimensions increased. When the end distance was 6d and the spacing was 5d, the optimal shear performance of the dowel rotary welding joint was achieved with a row spacing of 3d. The peak load was 3.36, 6.68, and 6.97 kN, respectively. The dowel rotary welding joint exhibited an obvious group effect, with the combination coefficient of group effect showing a trend of decreasing and then increasing with the increase of wood dowel diameter. When the diameter of the dowel was less than or equal to 10 mm, the combination coefficient of group effect was greater than 1.00.

Conclusion To ensure the shear performance of the joints, the joints should have an end distance not less than 5d, a spacing distance not less than 4d, and a row distance not less than 2d. The recommended end distance for joint design reference is 6d, with a spacing distance of 5d and a row distance of 3d. The joint combination coefficient of group effect of dowel rotary welding is influenced by the diameter, with a diameter range of 8−10 mm resulting in a large joint combination coefficient of group effect.