TM 5-5420-278-100035 000035 00-16BRIDGE ANCHORAGE (Contd)USE OF CABLE CLIPSBoth ends of the overhead cable are wrapped around a deadman and securedusing 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 overheadcable, 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 thecorrect 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 cableclip to attain maximum holding power.LENGTH OF THE OVERHEAD CABLEIn Appendix C of TC5-210, the calculation for the length of the overhead cable (infeet) is given as:CL = L + 250 ft (76.3 m) where CL is the required length of theoverhead cable (in feet), and L is the distance between the anchoragetowers (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 theoverhead cable. This approximation is based upon the most severe river and bankconditions and is intended for use as a planning figure only. There is no need tocalculate an exact cable length, but if the designer of a cable system so desires, theformula can be derived from information provided in TM 5-312.CABLE SAGThe ability of the anchor cable to hold the bridge decreases as the sag in theoverhead 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 cablesupports. Prior to connection of the bridle lines to the overhead cable, tension isapplied to the cable and the initial sag determined. A two percent sag (or less) isdesired. 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 whenthe bridge is connected to the overhead cable.
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