Nail and screw withdrawal strength of laminated veneer lumber made up hardwood and softwood layers

The objective of this research was to evaluate screw and nail withdrawal strength properties of veneer laminated lumber manufactured from poplar (Populus nigra) and beech (Fagus orientalis L.) in transverse, radial, and tangential directions. Ten and 13 layer laminated samples were produced in different thickness veneers of both species using two types of resins, namely polyvinylacetate (PVAc) and polyurethane (PU). Based on the results of this study it was found that layer thickness did not influence the withdrawal strength in transverse direction but strength values increased with increasing specific gravity of the samples in this direction. Overall strength properties in radial direction were found to be higher than that of tangential direction. Based on the statistical analyses resin type did not significantly effect withdrawal strength of both species.