Volume 19, Issue 2 (March 1991)
Mechanical Behavior of Nailed Joints with Various Side Member Materials
Research was conducted to define and compare the mechanical behavior of nailed joints connecting solid wood to eleven commonly used side member products frequently used in construction. Two hundred twenty eight (228) joints were laterally loaded to the allowable load defined by the National Design Specifications, unloaded to zero, then loaded to failure. Solid-sawn Douglas-fir and Engelmann spruce 2 × 4 nominal dimension lumber was used as the main members, while side member materials consisted of southern pine and Douglas-fir plywood of two thicknesses, oriented strand board (OSB), hardboard, particleboard, waferboard, insulation board, gypsum board, and western red cedar solid wood siding. Nail sizes were 6d and 8d common wire nails.
Experimental load-slip curves were developed for all joints tested. Information reported includes first and second cycle secant slip modulus, loads at 0.003 in. (0.0765 mm) and 0.015 in. (0.381 mm) slip, ultimate load, and ultimate slip. Parameters are also given for empirical equations describing the load-slip behavior of the joints. Comparative statistical analysis was performed using nonparametric multi-response permutation procedures.
The results suggest that for both main member species, the strength and stiffness behaviors of OSB, waferboard, particleboard, and ¾ in. (19.05 mm) nominal southern pine and Douglas-fir plywood were statistically indistinguishable. The stiffness of joints made with the higher specific gravity main member was generally statistically superior to joints made with lower density material. Strength was much less sensitive to this parameter. Joints made with western red cedar, insulation board, and gypsum board were substantially less stiff and strong than those made with the other side member products. Hardboard joints with a 6d nail performed similarly to particleboard, OSB, waferboard, and plywood joints connected with 8d nails. This suggests that hardboard could be used in applications where nail joint resistance is important.