Toronto’s Blackwell Bowick takes on Ivy League building challenge

What’s a Toronto-based structural engineering consultant doing at an American Ivy League university? Engineering the Brian C. Nevin Welcome Center, part of Cornell University’s Plantation Botanical Garden at its Ithaca, N.Y., campus.

At 6,000 square feet, the two-storey building is small, but it posed big challenges for Blackwell Bowick Partnership Ltd. The biggest was how to create “a practical (economical) structure” to meet the complex geometries of the building, a design by another Toronto firm, Baird Sampson Neuert Architects.

Calling it a “jewel box of a design,” Anthony Spick, Blackwell Bowick’s project manager, says the building, mostly made of steel, contains “a lot of curved geometries” for flooring. One of the main hurdles was how to orient the framing and the connections to allow for “practical” construction methods.

The engineer specified cranked (bent or curved) floor beams because the floor plates were shallow and the floors had overhangs in a number of directions. “It meant there were a few connections where beams had to be connected through other beams,” says Spick.

Engineers avoid connecting a beam through another beam when possible because it is expensive, he says.

Another engineering hurdle was how to deal with the thin floor plates with large overhangs adjacent to large openings. “Picture an atrium space with no columns below the floor and a thin floor plate,” he says.

The solution: The engineer used steel hangars connected to beams close to the floor edge and hung them from the roof beams, explains Spick. “If we didn’t have the hangars, the floor would have had to be thicker to be stiff enough and strong enough for the long span.”

The second floor of the two-storey building is a concrete slab on composite steel deck supported on steel beams. The roof is a steel deck on steel beams.

The steel was erected by New York-based Rochester Structural LLC. “The contractor told me that everything fit together perfectly,” says Spick, adding that the erector did a good job dealing with the complicated geometry.

In some ways, steel fabricator/erectors in New York State have it easy by comparison to their counterparts in Canada. Complicated steel connection designs are the responsibility of the structural engineer, not the erector, in the state.

Not so in Canada, where the fabricator/erector designs and details all connections, provides shop drawings and an engineer’s stamp of approval.

New York erectors are prohibited from using in-house engineers to approve shop drawings because it is seen as a conflict of interest, adds Spick. “It means the steel connection design shifts (unless they are standard connections) from the fabricator to the engineer of record.”

While on one hand an engineer has more responsibility in the state than in Canada, Spick says the rules governing engineers in New York allow them to “offload some work.” That is because to meet the International Building Code (the U.S. building code) project owners are required to hire third-party inspectors to inspect specific elements of a project, including structural steel.

“It relieves responsibility from the engineer of record to do inspections where special inspections have already been done,” says Spick. “In theory, on some projects the engineer of record might not even visit the site.”

For Blackwell Bowick, only three site visits were required for the duration of the project; a comparable job in Canada would require about a dozen visits, he says.

Spick suggests it makes sense for experienced structural engineering consultants like Blackwell Bowick to bid on more complicated projects in upper New York state because most of the American competition is from New York City, further from upstate New York.

The welcome center was one of the winners of Canadian Architect’s 2010 Awards of Excellence, given each year to architects and architectural graduates for buildings in the design stage.