TRUSS SYSTEM FOR DEVELOPING-COUNTRIES USING SMALL-DIAMETER ROUNDWOOD AND DOWEL NUT CONSTRUCTION

Through bolt with dowel nut connectors provide a means of constructing wood roof trusses from small round wood members. The joint is easy to fabricate and requires only drilling operations. Trusses constructed with these connectors could be suitable for housing, farm buildings, a nd light industrial buildings. Because trusses can be fabricated from small rapidly grown stems rather than from lumber sawn from old-growth material, this construction could provide an efficient means of meeti ng building construction needs, particularly in developing countries. Tests carried out on through bolts with dowel nut connectors in round, 6- to 7-inch diameter, yellow-poplar (Liriodendron tulipifera) specim ens gave axial strength values that ranged from a low of about 6,000 p ounds to a high of over 30,000 pounds. Results were strongly affected by splits in the wood. Proper placement of dowel nuts to avoid splits substantially affected strength results. Reinforcing the ends of split members with a wrap of strapping steel substantially improved strengt h.