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Wire ropes
for construction
and
suspension bridges
44
Wire & Cable ASIA – May/June 2009
It seems likely that wire ropes enjoy greater visibility than any other wire
and cable product. Since concealment is out of the question, architects and
engineers have learned to make a virtue of necessity by utilising the huge
sinews as design elements – with striking results. Wire rope suspenders and
cables are in the visual vocabulary of anyone who has ever driven over a
magnificent suspension bridge.
The new San Francisco Oakland Bay Bridge, now under construction and slated for
completion in 2013, is a case in point. The distinctive single-tower structure will be the first
suspension bridge designed without any connection between tower and deck. Its open
secret: the 75mm and 90mm wire rope hangers connecting the tower with the floating
bridge box girders.
The Bay Bridge will be beautiful to behold.
It will also carry some 280,000 vehicles daily — more than 102 million in a year. These
extreme static load requirements will be met by the same wire ropes that trace the sublime
profile of the world’s longest single-span SAS (self-anchored suspension) bridge. The
signature single tower will soar 525 feet. Access to its 2.56-foot diameter main cable will
be by way of wire rope assemblies.
Aesthetic and serviceable, wire rope rewrites an architectural adage. Form follows
function. It need not be subordinate to it.
Photo courtesy of GCR Eurodraw SpA