Abstract:The defects, especially for knots, seriously affect the bending properties of wood. Full scale specimens and clear specimens for bending test, cut from larch dimension lumbers with different kinds of knots, were applied to predict the accuracy of the modulus of elasticity(MOE) in bending and to improve the accuracy of MOE by multivariate regression analysis with density and knots information. According to the regression analysis results, the∑［(Ik/Ig)·(Mk/Mo)］ of all knots and the average density ρa showed the best predictive accuracy of MOE for full scale specimen(Ef), with 0.674 of R2 and 1.15 of RMSE. Based on the ratio of regression parameter of independent variables for density and knots information, the knots were less influential than density on influencing Ef. Finally, a simplified theoretical model that can be used to calculate MOE for larch dimension lumber, was defined as Ef/Ec=0.96-0.47∑［(Ik/Ig)·(Mk/Mo)］.
