Strength of OSB Scarf Joints in Tension

Ying H. Chui


The use of scarf joints to join panel products can be found in structural applications such as wood I-joists and stress-skin panels. Design specifications for plywood scarf joints have been available for decades. Corresponding information on oriented strandboard (OSB) is not yet available despite its status as a suitable alternative to plywood as a structural panel product. This project was conducted to provide such design information. Three hundred joints were fabricated and tested in tension in a dry condition. These included two nominal thicknesses of OSB (11 mm and 18 mm) from two manufacturers. The adhesive used for the joints was a resorcinol formaldehyde. The joint strengths were compared with the material strengths in tension. The results showed that optimum joint strength was reached when the scarf slope was about 1 in 7 irrespective of manufacturer and thickness. At the optimum joint slope, no loss of strength was observed compared with unjointed material. For slopes less than the optimum slope, normalized joint strength decreased slightly. As the scarf slope increased from the optimum value, normalized joint strength decreased to a value of about 0.35 for a vertical scarf (butt) joint.


Scarf joints;oriented strandboard;tensile strength;glued joints

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