TM 5-5420-278-10
0035 00
0035 00-16
BRIDGE ANCHORAGE (Contd)
USE OF CABLE CLIPS
Both ends of the overhead cable are wrapped around a deadman and secured
using cable clips. It is essential that the proper number of clips is correctly applied.
To determine the number of clips which must be applied to each end of the overhead
cable, use the following formula:
Number of clips at each end = (3 X CD) + 1
where CD is the diameter of the overhead cable, in inches.
These clips should also be spaced according to the cable size. To determine the
correct clip spacing (in inches), use the following formula:
Clip spacing (in inches) = (6 X CD) + 1
where CD is the diameter of the overhead cable, in inches.
When installing cable clips, the base of each clip should bear against the standing
(load carrying) end and the U-bolt should bear against the running (loose end).
(Refer to figure 11.) If clips are installed incorrectly, they will cause shearing,
excessive wear, breakage, or slippage of the cable. Always use the correct size cable
clip to attain maximum holding power.
LENGTH OF THE OVERHEAD CABLE
In Appendix C of TC5-210, the calculation for the length of the overhead cable (in
feet) is given as:
CL = L + 250 ft (76.3 m) where CL is the required length of the
overhead cable (in feet), and L is the distance between the anchorage
towers (in feet) and is given as: L = (1.1 X Gap) + 100 ft (30.5 m)
This formula provides an approximate value for the required length of the
overhead cable. This approximation is based upon the most severe river and bank
conditions and is intended for use as a planning figure only. There is no need to
calculate an exact cable length, but if the designer of a cable system so desires, the
formula can be derived from information provided in TM 5-312.
CABLE SAG
The ability of the anchor cable to hold the bridge decreases as the sag in the
overhead cable increases. (Refer to figure 12.) Sag is defined as the distance (in feet)
between the cable and the midpoint of a straight line formed by the two cable
supports. Prior to connection of the bridle lines to the overhead cable, tension is
applied to the cable and the initial sag determined. A two percent sag (or less) is
desired. Initial sag (in feet) may be computed as:
S = (.02 X L)
where S is the initial sag, and L is the distance between the towers.
The distance between the towers (L) is determined as:
L = (1.1 X G) + 100 ft (30.5 m)
where G is the width of the river, in feet.
An initial sag of 2 percent will usually result in a final sag of 5 to 7 percent when
the bridge is connected to the overhead cable.
