Size effects of width on tensile strength of visuallygraded Chinese larch lumber

The dependence between tensile strength and width of Chinese larch visuallygraded dimension lumber was investigated. Three different width dimension lumbers were parted into two groups: high visual grade and low visual grade. The ultimate tensile strength parallel to grain was tested under same test span. The width size effects of 5th percentile of tensile strength were estimated by the slope method and the parametric method. The results were as the followings: 1) Increasing the lumber width lowered the ultimate tensile strength parallel to grain. 2) The estimated width effect parameters were 0.29 in high and 0.33 in low for the 5th percentile of the ultimate tensile strength parallel to grain. 3) The parametric method could estimate the width size effects of the ultimate tensile strength parallel to grain.