. Handbook of railroad construction; for the use of American engineers. Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States .. . r chord,will be 250000 X 100 96 = 260,417 lbs. The manner of dimensioning thechord, and of splicing, is the sameas already described for Howes. SUSPENSION RODS. The first sets of rods, A B, A B,must sustain the whole weight ofthe bridge and load ; which is250,000 lbs. Each side 125,000lbs. ; and each end set of rods62,500 lbs.; and if each set hasfour rods, each rod
. Handbook of railroad construction; for the use of American engineers. Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States .. . r chord,will be 250000 X 100 96 = 260,417 lbs. The manner of dimensioning thechord, and of splicing, is the sameas already described for Howes. SUSPENSION RODS. The first sets of rods, A B, A B,must sustain the whole weight ofthe bridge and load ; which is250,000 lbs. Each side 125,000lbs. ; and each end set of rods62,500 lbs.; and if each set hasfour rods, each rod must support15,625 lbs. The rod being inclined, thisamount is increased by the fol-lowing proportion: — 12 (height) to (diagonal) as 15,625to 20,573 lbs. This is half-way between the tabular numbers for rods WOODEN BRIDGES. loo of 11 and If inches in diameter; If will therefore answer. The next set of rods must be considered as supporting the whole load, less the two end rjg. 68 a. panels, and so on as already explained for Howes bridge. The manner of applying the rods to the chords is shown in fig. 68 A. The bevel block should be connected with the block at the foot of the post, so as to prevent crushing the COUNTER RODS. As both top and bottom chords are always used in thisbridge, the counter rods have only the variable load on onepanel to resist. The action is, in amount, the same as thaton the counter braces in Howes bridge; but acts in a dif-ferent direction, and in the other diagonal. The weight of a passing load cannot be more than twothousand pounds per lineal foot. The panel being ten feetlong, the whole weight coming on two sets of counter rods,(one set in each side truss,) is twenty thousand pounds; orten thousand pounds on each set; and if there are put threerods in each set, we have 3,33S pounds per rod, which in-crease for inclination as follows: — 12: :: 3333: 4389 lbs., requiring a rod of three fourths inch diameter. The posts in this struc
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectrailroadsdesignandco
