May 27, 2010

FEATURE | Steel

Shops at Don Mills re-development project has a heart of steel

PETER KENTER

correspondent

The Shops at Don Mills, located on the former site of Toronto’s Don Mills Centre shopping mall, is one of the largest re-development projects in Canada.

Turning the former indoor mall outward, the Cadillac Fairview retail concept is a market village where pedestrians traverse streets and open squares as they shop.

At the centre of the village concept, there’s a heart of structural steel.

“The architects came up with the conceptual design and, as the structural engineering consultants, we came up with the framework,” says Domenic Fagotto a Group Leader for Structural Engineering with the Toronto office of Read Jones Christoffersen Ltd.

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Fagotto and the design team visited other “lifestyle centres” in the U.S. to research what client Cadillac Fairview wanted in the design.

“There are several issues with the steel that have to do with the design,” he says. “The shape of the structure itself was predetermined and decided upon before the actual exteriors. However, the surfaces of the retail units aren’t flat, but have a lot of canopies, parapets and movement. It’s a true streetscape and that was the intent.”

However, unlike a non-retail project, attracting tenants before the opening date could be tly enhanced by substantial completion of the building structure.

“We decided to erect the steel in phases, with the structural tender divided into two distinct packages,” says Fagotto. “On the first pass, we worked on all of the true structural steel, including the columns and the beams, and then on the second pass we tackled the architectural elements on the storefronts.”

The main structural contract was tendered as soon as practical to get construction started and awarded to a joint venture between fabricators and detailers M&G Steel Ltd. in Oakville, and Tresman Steel Industries Ltd. in Mississauga. The steel was erected by K C Welding in Borden.

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The streetscapes are made up of a series of one- and two-storey buildings ranging from small service stores to large retailers. The one-storey, double-height buildings were constructed using steel roof deck, long-span open-web steel joists, steel beams, girders and columns. The two-storey buildings were constructed along a similar plan, with the second floor made up of concrete on a composite steel floor deck, composite beams and girders.

Structural steel framing offered tenants wide column spacing ranging from 36 to 40 feet. which not only gives tenants flexibility to configure their spaces but allows for future reconfiguration of the space for subsequent tenants.

The shapes of the buildings had already been approved while the designs of the exteriors were being finalized.

Starting in early on the structural side gave the architects and designers additional freedom to complete the evolution of the exteriors. Using steel also allowed flexibility with revisions.

“Once the main structural elements were completed, we worked on all of the appendages that created the movement in the buildings,” says Fagotto. “This allowed us to meet the schedule and get the entire development to a point where it was as complete as possible to provide tenants with a feeling for the development and get their interest.”

The exterior elements were constructed of lightweight steel in such a way that retailers could easily adapt the units to their own corporate identity.

“We had three or four other sub-contractors working together on the steel elements of the canopies, projections and other storefront elements,” says Fagotto.

The total area covered by the $85-million project was 47,550 square metres.

Steel used on the main building structure totaled 2,500 tonnes with an additional 550 tonnes used to create the exterior facades.

Despite a particularly cold and snowy winter in 2009, work continued through the bluster.

“It was challenging to work within the time frame required to open the project on time,” says Fagotto. “But I would suggest that the team collaboration on this was exceptional, from general contractor Ellis Don Corporation to a great team of architects and sub-contractors.”

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