Experimental analysis of multiple staple joints in selected wood and wood-based materials

Effects of the number and spacing between staples on withdrawal and lateral resistance of stapled joints were investigated for selected wood and wood-based materials. Galvanized staples with legs that were 1.59 mm in diameter (16-gage wire) and 38 mm (1.5-in.) in length, and had chisel-end points, were used to construct the joints. Spacings between staples of 3.18 mm (1/8-in.) and 6.35 mm(1/4-in.) were tested. One, two, four, or eight staples were used to fasten the joint members that were of the following materials: Eastern cottonwood (Populus deltoides), red oak (Quercus falcata), yellow poplar (Liriodendron tutipifera), sweetgum (Liquidambar styraciflua), medium density fiberboard (MDF), and oriented strandboard (OSB). Direct withdrawal and lateral resistances of the joints were evaluated. Results indicated that, on the average, joints with higher density members provided the most resistance to withdrawal and lateral loads. Number of staples positively affected the joint resistance for all materials for both spacings, however, the relationship was not linear for most materials. General linear regression models, using material type and spacing as indicator variables, were developed to predict the withdrawal and lateral resistances.