The theory and practice of modern framed structures : designed for the use of schools, and for engineers in professional practice (1897)
Johnson, J. B. (John Butler), 1850-1902, Bryan, C. W. (Charles Walter), 1863-1927, Turneaure, Frederick Eugene, 1886- · New York : J. Wiley & Sons · leaf 399
ges are introduced where economy of design dictates their use. In general, it may besaid that the outline for the trusses of a swing bridge is governed by the same rules as forfixed spans. The most economical depth at the centre is about the same as for a fixed spanhaving a length equal to the… … Fig. 386. triangular pattern. In this, all of the lines of the truss form triangles. Fig. 386 shows theoutline for a triangular form of truss. The principal objection to this form of truss is the variation in the depth of the trussfrom zero at the ends to the maximum at the centre. The low depth of…
