WCA May 2009

Photo courtesy of GCR Eurodraw SpA

Wire ropes for construction and suspension bridges 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. 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. The Bay Bridge will be beautiful to behold.

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Wire & Cable ASIA – May/June 2009