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. 1912 Excerpt: ...are developed are taken by the concrete alone. Below the neutral axis, the distribution of stress is, however, different. When horizontal reinforcement is used, the tensile stresses are divided between it and the concrete. As long as the unit elongation of the lower fiber is less than the unit ultimate elongation of ...
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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. 1912 Excerpt: ...are developed are taken by the concrete alone. Below the neutral axis, the distribution of stress is, however, different. When horizontal reinforcement is used, the tensile stresses are divided between it and the concrete. As long as the unit elongation of the lower fiber is less than the unit ultimate elongation of concrete without reinforcement the division of the total tensile stress between the concrete and the reinforcement is determined by their respective coefficients of elasticity, the unit stress in the concrete at the level of the reinforcement and in the reinforcement where both have the same elongation, being directly proportional to these coefficients. When, however, the concrete cracks, these conditions begin to change; the nearer the load at a particular instant approaches the maximum load, for that beam, the greater the change. The cracks can in no case extend through to the neutral axis for below it there must always be a point at which the unit elongation is equal to the unit ultimate elongation of the concrete so that immediately above this fiber the concrete will be at the point of breaking while below it, it will just have broken. There must, therefore, be in every cross section of a beam, no matter to what extent the cracks are developed, a portion furnishing a source of tensile resistance, which would otherwise have to be provided by the reinforcement. If the concrete did not carry some tension the total tensile stresses that must be developed in a beam for equilibrium, could only be provided by an increase in the deformation of the reinforcement. In all formulas, that are in use in the design of reinforced con tensile stresses and this uncertain resistance of the concrete in tension is neglected. While it is entirely warranted to neg...
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