Specific Gravity and Mechanical Properties of Black, Red, and White Spruce and Balsam Fir.
Forest Service research paper,
FOREST PRODUCTS LAB MADISON WIS
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Nine mechanical properties and the specific gravity of black, red, and white spruce and balsam fir were measured on material collected at random from the growth range of each species. Significant changes, with 95 confidence, were observed in 31 to 40 instances four species, five properties, and two moisture contents that are commonly used in lumber and plywood design. Design values for modulus of elasticity and proportional limit in compression perpendicular to grain are based upon sample estimates of the mean. Average values for these properties are, in 9 of 16 instances, significantly higher than previous estimates. In only one case, the proportional limit of white spruce in the green condition, this study revealed a significant reduction. In modulus of rupture, compressive strength parallel to grain, and shear strength, design is based upon a 5 exclusion limit derived from the sample average and standard deviation.
- Wood, Paper and Related Forestry Products