Abstract
The effect of basic wood properties on strength and stiffness of timber as a full-size member is very different from that of small clear specimen. Recently a number of mechanical tests with timbers have been done. However the aims of those investigations are to get the mechanical data of timbers. Therefore which basic wood property is most effective parameter for the mechanical properties of timbers remains unclear. Especially the effects of anatomical properties of Cryptomeria japonica (sugi) timbers have not been studied. In this study, the effect of basic wood properties on strength and stiffness in bending of the timbers (1 : 400cm, b : 12cm, h : 21, 24 or 27cm) from sugi trees grown at three different sites in miyazaki district was investigated. Air-dry specific gravity, maximum knot ratio, juvenile wood ratio and ring width in juvenile and mature wood had slight effect or no effect on the mechanical properties of timbers. On the other hand, latewood tracheid length and S2 microfibril angle strongly affected the mechanical properties of timbers.
