LATERAL AND WITHDRAWAL STRENGTH OF NAIL CONNECTIONS FOR MANUFACTURED HOUSING

Current methods used in the design of nailed connections do not direct ly relate to the types of joints found in manufactured housing. These methods do not account for the construction practices used today, such as power nailing equipment, the use of nails with coated shanks, or t he fabrication of joints with filler materials separating main wood me mbers. A total of 640 joints were tested to investigate the effects of these five variables on lateral and withdrawal strength of nails: (1) Two wood species groups; (2) low- and high-humidity environments; (3) hand- and power-driven nails; (4) uncoated and coated nail shanks; an d (5) presence or absence of filler material in a joint. Tests verifie d that lateral strength increases with increasing wood density and tha t as environments become less humid and the moisture content of wood d ecreases, lateral strength and stiffness of nailed connections increas e. In the dry environment, the withdrawal strength of coated nails was almost 90% higher than that of uncoated nails in joints with an orien ted strandboard (OSB) filler and almost 40% higher when no filler was used. In high-humidity conditions, no differences were observed betwee n joints with coated nails and those with uncoated nails. In most othe r cases, the OSB filler reduced withdrawal strength by an overall aver age of 25%. This reduction is proportional to the amount of penetratio n into the solid wood member; therefore, nail length should be increas ed when an OSB filler is present.