Problem 15. Work the following problem to see how well you understand the concept
covered in step 11. The solution to this problem is found at the end of the lesson. Determine
the tie-wire spacing (in inches) if the uniform load is 756 pounds per linear foot and 2- x 4-
inch double wales are used.
A.
30
B.
43
C.
46
D.
72
Step 12. Determine the tie-wire spacing based on the tie-wire strength. Determine the tie-
wire spacing based on the tie-wire strength by dividing the tie-breaking strength (step 12) by
the ULW (step 10). Compute as follows:
tie - wire strength (lb) x 12 (in)
Tie-wire spacing (in) =
(13)
ULW (lb/lin ft)
If the strength of the tie wire is not known, refer to Table 5 for the minimum breaking
load for a double strand of wire.
If the answer contains a decimal, round down to the next lower whole number. For
example, for 11.4, use 11 or for 12.7, use 12.
Table 5. Average Breaking Load of Tie Material (in Pounds)
Steel Wire
Minimum Breaking Load (lb)
Size of Wire Gage
Double Strand
8
1,700
9
1,420
10
1,170
11
930
Barbwire
Size of Wire Gage
Minimum Breaking Load (lb)
12 1/2
950
13*
660
13 1/2
950
14
650
15 1/2
850
Tie Rod
Description
Minimum Breaking Load (lb)
Snap ties
3,000
Pencil rods
3,000
*Single-strand barbwire
18
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