Validation of Method for Estimating Element Strength Distribution of Laminated Veneer Lumber I. Laminating effect in the strength of laminated veneer lumber

摘要

In this study, we estimated the element strength distribution of Laminated Veneer Lumber (LVL) by the nonlinear least-squares method, supposing an element of veneer with adhesive. However, in order to validate this method, we must compare the element strength distribution estimated by this method with that calculated from experimental data. Then, we extracted specimens of lply, 2ply and 3ply with an adhesion layer from the remainders of LVL and carried out the same static tests as the experiments for LVL. Comparing the experimental values of lply and the estimated values in the previous report, the latter were larger than the former for Modulus of rapture (MOR) in the horizontal and vertical use directions, and tension and compression strengths. Accordingly, a laminating effect was suggested by those strengths. To ascertain this, the strength distributions of 2ply and 3ply were simulated by the experimental data of lply. Also the population distributions for the strengths of 2ply and 3ply were estimated by the maximum likelihood method. Comparing the strength distributions simulated by lply with the population distributions, the population distribution was larger for MOR in the vertical use direction, tension strength and compression strength. Therefore, in those strengths, it turned out that the laminating effect existed. On the other hand, we could not determine whether or not the laminating effect existed for MOR in the horizontal use direction.