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Structural Mechanics: Comprising the Strength and Resistance of Materials and Elements of Structural

by
Charles Ezra Greene

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 edition. Excerpt: ... f=lPHhh-y0)b. If the case is that of a wall, and P is the resultant force per unit of length, 6 = 1. As yo increases, / increases, until finally the stone crushes at the edge of the joint, or shears on an oblique plane as described in 23. Sometimes the pressure is not well distributed, from poor bedding of the stones, and spalls, or chips, under the action of the shearing above referred to, may break off along the edge, without failure being imminent, since when the high spots break off others come into bearing. P can never traverse one edge of the joint, if tension is not possible at the other edge, as the unit stress then becomes infinite. Some writers commit an error in determining the thickness of a wall by equating the moment of the overturning force about the front edge or toe with the moment of the weight of the wall about the same point. This process is equivalent to making the action line of P traverse that point. The centre of moments should be taken either at the outer edge of the middle third of the joint, when pressure is desired over the whole joint, or about a point at such a distance h--y0 from the front as will give maximum safe pressure at the front edge. A uniformly varying stress extending over three times that distance will equal P, as lately stated. A portion of the joint at the rear will then tend to open. Examples.--A short, hollow, cylindrical column, 12 in. external diameter, 10 in. internal diameter, supports a beam which crosses the or the stress, at either edge will be 80% greater and less than the mean stress. A joint, 10 ft. broad, of a retaining-wall is cut at a point 3 ft. 9 in. from the front edge by the line of the resultant thrust above that joint. If this thrust per foot of length of the wall is 28,000...
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