Instructions on Modern American Bridge Building by G. B. N. (George Bates Nichols) Tower
page 45 of 57 (78%)
page 45 of 57 (78%)
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Length, 7 feet.
Height, 1 foot. Width, 1 foot. Chords, 4--1/4 x 1/2 inch. Braces 4--1/4 x 1/8 " Lattice, 1/4 x 1/16 " This represented a span of 150 ft, a rise of 20 feet, and a panel of 15 ft. Weight, per running foot of bridge and load, was taken at 3000 lbs. The method of calculating the dimensions of this truss, from the foregoing data, is as follows. The half number of panels is 5, and the lengths of the corresponding diagonals (neglecting fractions) are --------- /20² + 15² = 25 feet. [TeX: $\root{20^2 + 15^2} = 25$] \/ --------- /20² + 30² = 37 " [TeX: $\root{20^2 + 30^2} = 37$] \/ --------- /20² + 45² = 49 " [TeX: $\root{20^2 + 45^2} = 49$] \/ --------- /20² + 60² = 64 " [TeX: $\root{20^2 + 60^2} = 64$] \/ |
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