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before these records were compiled; consequently it is to be hoped that bridge engineers will soon learn to utilize properly the vast amount of
information collected by the author in his many years of practice as a
bridge specialist and presented to the engineering profession in his magnum opus.
The following examples and their solutions will illustrate how the diagrams are to be used and how quickly they give results:
Example No. 1
What is the weight of structural steel in a single-track, steam-railway,
Class 60, riveted-truss bridge built of carbon steel and consisting of one
420' through span, two 265', two 215', and two 165' deck spans for a
proposed crossing of the Missouri River?
Solution
From Fig. 55i on p. 1228, and Fig. 551 on p. 1231 of B.E., we have the following:
1 420' Thro. span @ 5,450 lbs. = 2,289,000 lbs.
2 265' Deck spans @ 2,675 lbs. = 1,418,000 lbs.
2 215' " " @ 2,060 lbs. = 886,000 lbs.
2 165' " " @ 1,620 lbs. = 535,000 lbs.
Total metal in superstructure = 5,128,000 lbs.
Example No. 2
A double-track, steam-railway, Class 55 bridge, having a total length of
820' from end to end of superstructure, is to be built so close to high water
that half-through plate-girders will be required. Assuming that there will
be 10, 11, 12, or 13 spans of equal length, what will be the total weight of
metal for each case?
Solution
Ignoring the small spaces over piers between ends of girders, the various
span-lengths will be 82, 74.5, 68.3, and 63.1 feet. Referring to Fig. 55r,
on p. 1237 of B.E., we find the following weights of metal per lineal foot
of structure; 3,860, 3,700, 3,550, and 3,420. The total weights of metal
will, therefore be,
3,860 lbs. X 820 = 3,165,000 lbs.
3,690 lbs. X 820 = 3,026,000 lbs.
3,550 lbs. X 820 = 2,911,000 lbs.
3,460 lbs. X 820 = 2,837,000 lbs.
Example No. 3
What is the weight of metal in a double-track, steam-railway, Class 65,
pin-connected, Pratt-truss bridge, built of carbon steel and consisting of
five 330' through spans?
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