Modulus of Elasticity of Kiln-Dried Lumber

The modulus of elasticity (MOE), moisture content, and density were measured on boards of kiln-dried Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] of four grades in sizes from 2 by 4 to 2 by 12 from three manufacturing locations. Approximately 60 boards were selected from each classification. Boards were tested in flexure using an 11-foot span with the load applied at the midpoint. The Kruskal-Wallis test was used to evaluate the effect of size, moisture content, and manufacturing location upon average MOE and it indicated that there was no significant difference in the mills. Except for three instances, moisture content had no effect upon MOE within a grade. This was attributed to some characteristic which may affect both the stiffness and the drying characteristics in such a way as to cancel the expected effect of moisture content on mop. Value of average MOE varied from 1.687 x 106 to 2.279 x 106. The 2 by 4 and 2 by 6 sizes had higher values of MOE at one of the mills where logs were segregated such that these sizes were produced from smaller, second-growth, higher-density logs.

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