Analysis of classic arches; three hinged, two hinged, and hingeless, of steel, masonry, and reinforced concrete - Tapa blanda

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 Excerpt: ... the elastic theory to the computation of stresses in the hingeless stone arch is simple and offers much less difficulty than any other method. This is one of the purposes of the present work; because, notwithstanding its accuracy and the able analyses in which Winkler, Muller-Breslau, Mohr, Melan, and others have presented it, the elastic theory finds only a limited application on account of its intricacy. Various methods for finding the stresses in arches are extensively employed, which are more or less of an experimental character. The one in which the reciprocal polygon is so balanced that its rays are confined to the middle third of the arch rib is most favored. In this method one-half the span is loaded with live load, temperature and other stresses being generally neglected. This is known as the "one-third method." The application of this method to the arch in the preceding example would indicate that the dimensions given to the arch rib were sufficient for concrete; the computation by the correct method, however, proves the arch to be weak. The one-third method really makes an assumption and then proceeds to shape the computation to prove the assumption correct. Though it may be true that the many factors which influence the erection of the arch will modify its stresses, it is, nevertheless, a rational method, employed in all engineering constructions, to first ascertain the true stresses exerted in a structure, and then make such allowances as are dictated by a regard for safety. It is not the object of this work to condemn any method; on the contrary, for large arches the author has recommended at the beginning of this article the application of the one-third method for the preliminary determination of an approximately correct arch rib; ...