January 29, 2010

HALSALL ASSOCIATES

The Newmarket Operations Centre consists of an office building and a maintenance facility connected by an expansion joint so as to appear as one structure.

Steel construction

Newmarket Operations Centre joins two structures

DON PROCTER

correspondent

The 7,000-square-metre Newmarket Operations Centre will consolidate three municipal departments (public works, parks and maintenance) into one complex when it is completed later this year.

It also has design and engineering features not often found in this type of municipal building.

“There were several structural steel engineering challenges required to help the architect achieve his vision of a new civic landmark for the town (of Newmarket),” says Andrew Solda, project associate with Halsall Associates Limited, structural designer for the project.

The complex consists of two independent structures, an office building and a maintenance facility, connected by an expansion joint in a way so as to appear as one building.

It is common to engineer a separate lateral system for each building with steel bracing to allow two joined buildings to move independently.

However, the layout of the office area did not provide any opportunity to hide the bracing from public view, so Halsall engineered steel “moment frames” in two directions instead to provide for building support and stability.

The moment frames presented challenges for the engineering team, says Solda. “When you have a moment frame in two directions it means that certain corner columns are bending in both directions.”

In other words, make the columns stiff in both directions, an atypical engineering move. “Some of the design and detailing was challenging but this system provides a more versatile structure (flexible design) than a system of bracing.” The steel detailer for the project was Telco Steel Works Ltd.

While the fabrication and erection was straightforward, the centre had numerous non-standard connections that are atypical of facilities of this type, says David Garbuio, general manager of Telco.

“The skeletal steel structure might have looked like any simple box during erection, but the structural design and fabrication “is very much in line with a more complex multi-storey architectural structure.”

“In my opinion, the structural designer has achieved the architect’s design intent, while overcoming some significant structural hurdles, in a visually subtle way, using structural steel,” says Garbuio.

The building, which includes several significant architectural features, won an architectural Award of Excellence from Canadian Architect magazine. One of the architectural features of the municipal complex — the atrium — came with its own set of complications for the engineer. To make it column-free, the roof is supported on two 36-metre trusses which rest on boxed columns that allow the trusses to bend in both directions, he says. Special detailing was required from Telco for the boxed columns because they are exposed to the public.

The atrium features a showpiece staircase to upper and lower offices. To meet the architectural specifications, Halsall engineered a “very light looking structure” that was designed to minimize vibration — a potentially big problem eliminated through computer modeling and analysis.

Engineering cantilevered catwalks to reduce deflections and minimize vibration had its own hurdles, he adds.

Another architectural feature that posed structural engineering and detailing issues is the maintenance building’s steel bifold garage doors. The doors — commonly seen on aircraft hangars — fold in the middle and fold up.

Clad in a curtainwall, the steel doors required “a lot of finicky steel detailing” to ensure weather tightness and to attach the doors to the support structure while meeting the extra lateral loading imposed on the support columns.

“The lateral loads are much higher than ordinary garage doors,” Solda points out.

Another engineering feat was how to accommodate the space for a 10-ton vehicle maintenance crane.

Halsall engineered a steel track and girder system to support the track for the crane hoist and running track supplied by the crane manufacturer.

“The challenge was that the running beam track had to be connected approximately 600 millimetres outside (eccentric to) the column face so it could run back and forth freely,” says Solda.

“We had to make sure that the columns could take that kind of bending and that the beams sitting on the running girders were very stiff and could take lateral forces of the crane stopping.”

The new building consolidates staff offices, meeting and training spaces, an emergency command centre, a works yard, facilities for town vehicle storage, repair and washing and interior and exterior materials storage.

It is built at two elevations, with parking level with the atrium’s green roof which is designed to appear to be a courtyard linked to the parking structure.

“The architect cleverly used the change in grade to create the appearance of two distinct structures from the north view. This amazing design feature provides a creative and signature look to the building,” says Solda

The building is a design by Rounthwaite Dick & Hadley Architects Inc., of Toronto.

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