Figure 14

Failure of short column by oblique shear.

TABLE VIII
SHEARING STRENGTH ACROSS THE GRAIN OF VARIOUS AMERICAN WOODS
(J.C. Trautwine. Jour. Franklin Institute. Vol. 109, 1880, pp. 105-106)
KIND OF WOOD Lbs. per sq. inch KIND OF WOOD Lbs. per sq. inch
Ash 6,280 Hickory 7,285
Beech 5,223 Locust 7,176
Birch 5,595 Maple 6,355
Cedar (white) 1,372 Oak 4,425
Cedar (white) 1,519 Oak (live) 8,480
Cedar (Central Amer.) 3,410 Pine (white ) 2,480
Cherry 2,945 Pine (northern yellow) 4,340
Chestnut 1,536 Pine (southernyellow) 5,735
Dogwood 6,510 Pine (very resinous yellow) 5,053
Ebony 7,750 Poplar 4,418
Gum 5,890 Spruce 3,255
Hemlock 2,750 Walnut (black) 4,728
Hickory 6,045 Walnut (common) 2,830
NOTE.—Two specimens of each were tested. All were fairly seasoned and without defects. The piece sheared off was 5/8 in. The single circular area of each pin was 0.322 sq. in.

TRANSVERSE OR BENDING STRENGTH: BEAMS

When external forces acting in the same plane are applied at right angles to the axis of a bar so as to cause it to bend, they occasion a shortening of the longitudinal fibres on the concave side and an elongation of those on the convex side. Within the elastic limit the relative stretching and contraction of the fibres is directly[9]] proportional to their distances from a plane intermediate between them—the neutral plane. (N1P in [Fig. 15].) Thus the fibres half-way between the neutral plane and the outer surface experience only half as much shortening or elongation as the outermost or extreme fibres. Similarly for other distances. The elements along the neutral plane experience no tension or compression in an axial direction. The line of intersection of this plane and the plane of section is known as the neutral axis (N A in [Fig. 15].) of the section.

Figure 15

Diagram of a simple beam. N1P = neutral plane, N A = neutral axis of section R S.