...are made mostly from 8-in.-dia curved steel tubes. Sail and cloud assemblies hang from 46 “stalactites,” which are also tubular steel elements. Stalactites hang from roof framing.
There are 260 tons of curved steel, says George Korkidakis, senior project manager at the North Lauderdale office of the structural-steel fabricator-erector ADF International Inc. While declining to provide ADF’s contract price, Korkidakis says the curved elements cost three or four times as much as straight ones, thanks to more material, more complicated fabrication, more costly transportation and more expensive field welding.
In its shop, ADF detailed the frames using BIM and then preassembled the actual physical pieces to assure a perfect field fit-up. Using high-tech surveying compatible with its fabrication system, ADF checked the preassemblies against the BIM before dismantling and shipping them to the site.
On the floor of the enclosed hall, crews reassembled the frames using temporary bolted connections. Hydraulic cranes picked the frames and workers hung them from the stalactites before final welding. Fit-up was excellent, says Korkidakis.
Framing installation for the atrium rooms followed a similar strategy, except the rooms are freestanding.
Next, workers installed the curved light-gauge cold-formed steel stud-and-track system for the clouds and sails. The system, including all its attachments to the frame, was engineered by Mayer Structural Design Inc., Miami Beach, under contract to the job’s design-build drywall contractor, Lotspeich Co. Inc., Miami. Mayer also collaborated with Lotspeich on the method of erecting the system, based on a coordinate geometry system provided by Mayer. To engineer the system, Mayer developed 3D BIMs, which detailed the framing layout, coordinates and profiles of the studs and joists that make up the sails and clouds, says Haskel Mayer, president.
Mayer’s system was fabricated into a kit of parts by Radius Track Corp., based on Mayer’s models. The Minneapolis-based firm has a patented method of crimping the members to provide the correct curved profiles using bending tools. “We figured out how to do this out of sheet metal, which would follow the exact shape Gehry wanted,” says Chuck Mears, Radius Track’s founder and CEO, who has worked on other Gehry interiors.
The kit of parts contained 259 different surfaces, for a total of 505,683 sq ft, installed and covered with drywall. There are 3,432 studs totaling 12,385 linear ft and 2,632 tracks totaling 11, 519 linear ft. Of the profiles, 94% are one of a kind, says Mears.
Perhaps the most challenging part were the knife edges at every surface edge or corner that is not a right angle. To the builders, the knife edges seemed as sharp as a samurai sword, says Mears. For the edges, Radius Track devised a way to create diagonally braced frames, each unique, that provided the necessary geometry. For example, in a typical four-sided frame, the length of only one member would be universal, but the length and angles of the other three frame sides could vary up to 30% as the surface evolved.
“Chuck Mears and Radius Track made it possible to reproduce the coordinate geometry,” says Joaquin Riera, Lotspeich’s vice president.
Lotspeich’s crew connected Radius Track’s curved, cold-formed steel box beams to the steel-tube frames via welded steel fittings that were adjustable. A high-tech survey, which was imported into the BIM, compared actual tube locations to BIM locations. The survey was crucial because the tubes established the exact final geometry for the finished surfaces, says Mears.
Sail and cloud assemblies typically are connected to the stalactites indirectly through hanger assemblies because the connection points did not always line up with stalactite locations. Curved box beams are connected to the stalactites via A-frame assemblies; then, curved studs and tracks are connected to the box beams via two individual hangers per stud. At other locations, wide-flange beams were used to make multiple connections to a single stalactite and allow for the final adjustment of the hanging-point location.
“If we had been on board just six months earlier, we could have helped better position” the stalactites to line up more directly with hanging points of the cloud and sail assemblies, says Mears.
The architect had envisioned a prefabricated panel installation for the stud-track and drywall assemblies, but Lotspeich shifted to in-place erection. Prefabricated panels would have been “very difficult to maneuver into place” because of their size and weight, says Riera. Additionally, the continuous box-beam support system did not work well with either panelizing or prefabrication.
Facchina devised scaffolded work-access platforms for the clouds, sails and attic infrastructure above them. A hanging scaffold was used for the main sails above the stage, which allowed for the concurrent construction of the stage. Once the stage was complete, Facchina erected large “dance floor” work platforms off of falsework towers set on the stage subfloor, which freed up the seating area for work. For the attic mechanical ductwork, crews hung a platform from cables embedded in the roof slab. The platform was designed to be lowered as required to install multiple layers of duct and pipe, installed before the sails were framed.
To keep noise down, air has to move slowly through ductwork. That goal resulted in ductwork that is four times larger than what it would have been for a commercial space, says Cosentini’s Ceasar. “Working in the ductwork, within limited space and around complex geometry, was challenging,” adds Vazquez.
Facchina got a temporary certificate of occupancy in late October. But then, workers had to remove finishes in four or five areas and add fire sprinklers requested at the eleventh hour by city building and fire officials. “It’s like finishing a gorgeous [mural] and then taking it out,” says Vazquez.
In hindsight, the contractor says he would have gotten permitting officials involved earlier in the process, perhaps showing them BIMs so they could better fathom the spaces. “They really didn’t get a feel for the job from the 2D drawings we submitted,” he says.
The hiccup did not dampen the team’s spirits. All involved consider the project a major victory, including the workers. “It was a challenge, but they took a lot of pride in what they were doing,” says Vazquez.