|----------------------------------------------------------------------| | TABLE XV | |----------------------------------------------------------------------| | EFFECT OF DRYING ON THE MECHANICAL PROPERTIES OF WOOD, SHOWN IN | | RATIO OF INCREASE DUE TO REDUCING MOISTURE CONTENT FROM | | THE GREEN CONDITION TO KILN-DRY (3.5 PER CENT) | | (Forest Service Bul. 70, p. 89) | |----------------------------------------------------------------------| | KIND OF STRENGTH | Longleaf | Spruce | Chestnut | | | pine | | | |----------------------------+-------------+-------------+-------------| | | (1) (2) | (1) (2) | (1) (2) | | | | | | | Crushing strength parallel | | | | | to grain | 2.89 2.60 | 3.71 3.41 | 2.83 2.55 | | Elastic limit in | | | | | compression | | | | | parallel to grain | 2.60 2.34 | 3.80 3.49 | 2.40 2.26 | | Modulus of rupture in | | | | | bending | 2.50 2.20 | 2.81 2.50 | 2.09 1.82 | | Stress at elastic limit in | | | | | bending | 2.90 2.55 | 2.90 2.58 | 2.30 2.00 | | Crushing strength at right | | | | | angles to grain | | 2.58 2.48 | | | Shearing strength parallel | | | | | to grain | 2.01 1.91 | 2.03 1.95 | 1.55 1.47 | | Modulus of elasticity in | | | | | compression parallel to | | | | | grain | 1.63 1.47 | 2.26 2.08 | 1.43 1.29 | | Modulus of elasticity in | | | | | bending | 1.59 1.35 | 1.43 1.23 | 1.44 1.21 | |----------------------------------------------------------------------| | NOTE.--The figures in the first column show the relative increase in | | strength between a green specimen and a kiln-dry specimen of equal | | size. The figures in the second column show the relative increase of | | strength of the same block after being dried from a green condition | | to 3.5 per cent moisture, correction having been made for shrinkage. | | That is, in the first column the strength values per actual unit of | | area are used; in the second the values per unit of area of green | | wood which shrinks to smaller size when dried. | | |