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NYC 9/11 Public Portal Document

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wa.s attached for lateral stability through its horse- .shoe truss.

'a I 1 ai Ml Wiet la : “Miraculously,” says Zborovsky, a three-story 1 pile of debris from One WTC, the downed ■ pedestrian bridge that gave access to the garden ■; from the WTC and the damaged Three WFC i was propping the Winter Garden’s broken I horseshoe truss. I But the fire department, searching for sur- I vivors, was eager to remove the debris. Fortu- B ' ill J nately, T-T also was representing New York City’s 3 Dept, of Design and Construction as structural : consultant at Ground Zero and was able to con- I : vince officials to leave the debris until workers j could shore and brace the structure. S . From mid-September to December’s end, -- 1 (1 ews from local construction firm AMEC and I j scaffolding contractor Atlantic-Heydt Corp., g I Brooklyn, N.Y, installed compression struts | I If) ween the ends of the garden’s roof arches J if I and bracing at critical locations. Workers had to > HiisSWl a 1 cut 5-ft-square shafts four stories deep through s WEi TIE TIP Trolley system let glaziers do their work In just 4.5 months. the thicket of debris to install shoring towers § under damaged roof arches. The trick, says S Zborovsky, was .staging the work to prevent further compro­ Q

mise to the structure. During the operation, other than some broken glass falling, there were no secondary collapses. Beyond T-T’s structural assessment survey and shoring and 2 debris removal, the city would not allow any work on the gar- S den until January, when it turned the building back to the | owner. “We couldn’t get people to the site because the pieces g of the corner of Three WFC, including One WTC steel, were | dangling precariously over the Winter Garden,” says White. S ’Wliite, at Ground Zero since Sept. 13, didn’t waste the wait- | ing time. Hired for the garden’s fine demolition and restora- £ tion. Turner used the “delay” to collect original drawings, S procure replacement glass, order steel and lock up time for § fabrication of replacement steel, stone and the curtain, wall. S The earliest preliminary schedule for the Winter Garden | redo called for completion by late October or November | lEW Flow 0081 Dream team’s (I. to r.) Zborovsky. Kanner, 2002. But Brookfield wanted the work done by the anniver- | White, architect Rafael Pelli and Copeland In front of new wall, sary of Sept. 11, so WTite promised to finish by Sept. 5. Witli . 2^0 activities, die schedule ha,s not changed since Oct. 1, oth- 5 direction, trusses radiate from an apse at the east end of the 'ci than the east facade redesign, he says. roof, across from Ground Zero. Loads go to drilled-in caissons. Turner’s approach was to work in as many t UJ

Upon initial inspection of the damage, locally based Thorn- areas as possible at die same time and to get ton-Tomasetti Engineers (T-T) , tire garden’s original structural double duty from as many systems as possible. consultant, thought the building was unsalvageable. Many arch­ The “dance floor,” a work platform built 67 ft es were damaged or partially down, a.s was the east facade and a above the Winter Garden's first floor, is an large portion of the east floor framing. Most seriously, the sys­ example. The platform provided a safety net tem for lateral stability, a 350-ft-long, 50 to 60-ft-wide horseshoe­ for roof workers, protected workers below shaped horizontal diaphragm truss within the fourth floor, wa.s from falling objects and weadier and gave helfand heavily damaged at its most critical area, the 50-ft-long turning workers roof access from the interior. Anoth- § point at the curve of the horseshoe. — I Even more worrisome, .says die engineer, die inner ■ edge of the truss was still attached to its edge girder. But the breached girder had lost structural stability'. If lateral l orccs were to push the horseshoe apart, the 11 ii - . (H, III Vn « 5

whole structure would have collapsed, says Leonid B. Zborovsky, a T-T principal involved in the original Ww’Ww'*’' 'ft project and the repair. If that had happened, there would have been dam­ “ * § age to the 51-story Three WFC, to which tire garden IIEWII Part of Ground Zero viewing fence is set to be done by Sept. 11. 51

September 9, 2002/ENR 9

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