Variation of tensile strength along the length of lumber

Summary The within member variation of tensile strength parallel to grain in nominal 38×89 mm No. 2 Spruce-Pine-Fir lumber has been experimentally evaluated. Window analyses yielded the within member tensile strength cumulative probability distributions of lumber segments with various lengths. Semivariogram and regression analyses have been performed to characterize the spatial correlation of the tensile strength of lumber. The results indicate that the tensile strength values within a piece of lumber separated by a distance greater than 1.83 m can be considered statistically independent.The Authors gratefully acknowledge the support of the Forestry Canada and the technical assistance of Mr. H. Sue, Mr. B. Deacon and Dr. J. Cook for this study. The research was performed while the principal author was working at Forintek Canada Corp.