January 28, 2010

FLYNN CANADA LTD.

A ribbon of stainless steel, dubbed the borealis, snakes around and through the Art Gallery of Alberta forming the soffit, roofs and architectural elements.

FOCUS | Steel

Art Gallery of Alberta addition showcases steel

PETER KENTER

correspondent

The addition to the Art Gallery of Alberta (AGA) was designed to be a showpiece, anchoring the arts firmly in downtown Edmonton’s Sir Winston Churchill Square.

While six structural steel columns support the 27,000 square-foot addition, its most striking feature, dubbed the borealis, is an apparently continuous ribbon of stainless steel that snakes around and through the building, forming the soffit, roofs and architectural elements.

The borealis was designed by Randall Stout Architects Inc. of Los Angeles to represent the northern lights, a frequent feature of the Edmonton night sky. The borealis winds through the gallery, emerges to form a roof canopy at the front entrance, then drops down to create a “snow cone,” that will collect snow and ice from the building’s roof.

Construction manager and general contractor Ledcor Construction Ltd. of Edmonton chose Flynn Canada Ltd. to help realize the sinuous structure in a design assist contract. Flynn partnered with A. Zahner Company of Kansas City to provide the fabricated shapes. Together they worked with both the architect and the structural engineering consultant, DeSimone Consulting Engineers of San Francisco, to refine the Building Information Modeling (BIM) model into a real-world structure.

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A ribbon of stainless steel emerges to form a roof canopy at the front entrance.

Flynn and Zahner had previously worked together on the recent Art Gallery of Ontario redesign.

“The BIM model governed the project,” says John Mplias, Flynn Canada’s senior project manager on the AGA.

“That’s what governed the project. It was a real representation. We could zoom in, rotate and even slice-and-dice to get a complete understanding of how all of the components had to fit together. This inevitably saved a great deal of time and resources.”

BIM was the primary enabling tool between the major trades, to install such features as glazing, and structural architectural panels.

Although the contractor’s responsibility extended to the skylights, glazing, railings and roof, the borealis was one of the most challenging parts of the contract, says Art Bundschuh, vice-president, Mid-West Region with Flynn.

“It was divided into 10 sections,” he says. “The project presented itself as a jigsaw puzzle with no two pieces exactly alike. Every bullnose, every panel, had a unique ID.”

And while the design was intended to make the ribbon of steel appear continuous, the real-life product had to respect the art gallery’s building envelope, which needed to protect climate-sensitive artwork. Had the borealis formed a true continuous path, it would have acted as a conductor to the outside air, where winter lows approach -50C.

“At a corner where two sections of curtain walls came together, for example, the model provided a single finite line to communicate a junction,” says Bundschuh.

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Workers on the Art Gallery of Alberta addition assemble a section of the ‘borealis’ architectural feature.

“We took this information and understood that two curtain wall extrusions, air seals, etc. were required to provide a functioning corner, all the while adhering to the original design intent.”

Where the borealis and its supporting cantilever appears to penetrate the envelope, connections were comprised of steel face plates separated by one-inch thick blocks of oak, a wood which offers low thermal conductivity. This design allowed only the connection bolts to bridge the envelope.

“Neil Prunier of Randall Stout Architects was on site on a regular basis,” says Mplias. “When unforeseen design issues arose, his presence allowed us to make quick decisions which ensured the production schedule remained intact.”

All sub-trades used the same model, interpreted it and were also required to provide real-world solutions to interface with the work of the other contractors. Steel detailer Empire Iron Works, for example, took computer modeling information to cut the structural steel precisely, using lasers at its Edmonton plant.

“The gallery is in downtown Edmonton, thus manoeuvreing of equipment, materials and material lay-down and staging was challenging,” says Mplias. “We solved this by instituting just-in-time delivery of materials that could be installed over the coming two to three days. So many facets in glazing and metals required an integrated dance between our two groups.”

Panels supplied by Zahner defined the shape of the borealis. Metal skins were applied to the framework, and then glazing was installed. The lone exception was the third floor terrace, where a completed assembly was hoisted into place after glazing.

Begun in November 2008, the borealis was completed in plenty of time for the new AGA’s January opening.

“The entire construction team worked together to make this special project a resounding success,” says Bundschuh.

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