17
DESIGN OF ICE BOOMS
flexible fiber core wire rope should be used for members to be
handled by heavy equipment. Fourth, because members are con-
stantly wet, galvanized wire rope is used to minimize damage
from corrosion. Fifth, because wire rope sizes over 23 in. (57.5
cm) in diameter are very difficult to handle, the structural load
and therefore the wire rope size can be reduced by shortening the
span length of the boom cable.
Anchoring systems
For midstream river-bottom anchors, the anchor cable should
have a minimum "scope" of 7 (7 horizontal to 1 vertical). The
Engineer Manual, Ice Engineering (U.S. Army Corps of Engi-
neers 1982) recommends a scope of 12. This allows the structural
system to absorb impact loads while maintaining a relatively
horizontal load on the anchors. These midstream anchors can take
many forms, such as ship anchors, driven piles, drilled and grouted
piles, and buried steel plates. Examples of anchor types are shown
in Figure 7. If the year-round river use conditions allow, perma-
a. Deadman and
pedestal type anchor
used at the land end.
b. Buried concrete-
filled pipe used as land
end anchor. Note I-
beam reinforcement.
c. Sheet-piling cell
serving as a mid-
channel anchor.
7. Anchor types
illustrated.
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