Retractable arch will star at Olympics

There will be no "curtain call" for the medal winners at the Winter Olympics in Salt Lake City on Feb. 8-24. That's because the world's largest unfolding arch will replace traditional stage curtains on the presentation platform of the 20,000-seat Olympic Medals Plaza in downtown Salt Lake City. To kick off the nightly medals ceremony, the arch will retract from a 35-ft.-high wall to a 6-ft.-thick semicircular ring that frames the stage. While closed, the arch's translucent surface will be back lit.

Chuck Hoberman, inventor of the retractable toy sphere, teamed up with New York City-based structural engineer Buro Happold Consulting Engineers to design the structure, which is composed of aluminum latticework backed by 96 translucent polycarbonate panels, each with three pinned joints. Scenic Technologies of New Windsor, N.Y., fabricated the components.

The arch's geometry, unusual load conditions and size required Happold to develop an unusual support system to resist gravity and wind loads. Tension cables that attach at the center of the semicircle support the weight of the screen. Cable sheaves pull the weight to an independent steel arch structure. At the base of the arch, the lowermost panels run along a sliding track, enabling the entire system to retract, while also helping to support vertical and horizontal loads. The firm utilized 3-D modeling to simulate the structural performance of the system.