Canadian Consulting Engineer


Toronto builds taller but sticks to old ways of building

Structural engineers and developers responsible for raising the skyline of Toronto to new heights met on November 5. The Canada Chapter of the Council on Tall Buildings and Urban Habitat (CTBUH) held a breakfast meeting at the Faculty Club on...

Structural engineers and developers responsible for raising the skyline of Toronto to new heights met on November 5. The Canada Chapter of the Council on Tall Buildings and Urban Habitat (CTBUH) held a breakfast meeting at the Faculty Club on the University of Toronto’s downtown campus with around 90 people attending.

The theme was: “What new technologies and techniques are influencing the way we build tall in Toronto? What are we doing well and what are we missing?” After three short presentations on new technologies that are starting to be used on towers in Toronto, a panel discussion was moderated by David Bannister of WSP.

During the panel discussion everyone agreed that Toronto had entered a “new paradigm” for residential building, moving from what were 30 or 40 storey buildings, to towers that are 70 and 80 storeys tall. See CCE article, “Growth Spurt.”

Despite the soaring profiles, the city’s construction industry tends to stick to its traditional ways of building. Panelist Johann Schumacher, vice-president of development with Oxford Properties, said that the use of new technologies requires a new mindset and means taking a risk. But in North America the default is to stick with the tried and tested methods.

If we are to “let architects out of the bag,” he said, new technology needs to be involved. He said tall developments in the Middle East drove changes with their “crazy shapes,” which couldn’t be built using traditional methods.

The challenge in the commercial market here, Schumacher said, is that any new approach or technology will only be adopted if it makes financial sense.

The other panelists, which included Ben Rogowski, executive vice president of Canderel, Peter Kofman, president of Projectcore, and Niall Collins, senior vice president of development with Cadillac Fairview, agreed. “Our market is so competitive it becomes a financial decision,” said Rogowski. They discussed how at a certain point it doesn’t always make financial sense to build taller because you then have to include more damper systems, elevators, parking allowances, etc.

A person in the audience said it would be interesting to look back in five years to see how many of the planned new towers were actually built. Another asked, “Are we living in a fantasy world, designing for a market that doesn’t exist? Toronto does not have the oligarchs and foreign investment that New York City and the Far East have.”

The first presentation on a new technology was by David Ruhl, P.Eng. of RWH Engineering and HCM. He gave a quick overview of shotcrete foundation walls, pointing out that they eliminate the need for formwork, are ideal for curved radial walls, and provide a “seamless burnished architectural finish.”

The second and third technologies both offered ways for developers to maximize the space available in a tower to lease or sell.

Professor Constantin Christopoulos, P.Eng. of the University of Toronto presented Kinetica’s Coupling Dampers. Developed at the university in collaboration with structural engineers at Yolles, the patented damping system provides both wind and earthquake vibration protection. The dampers consist of layers of viscoelastic material alternating between layers of steel plates. Installed instead of concrete beams, they are configured horizontally between large structural walls. Because a damper isn’t required at the top of the tower, more valuable penthouse space is available for leasing.

Tibor Kokai, P.Eng. of Read Jones Christoffersen gave a brief talk on post-tensioning. Its use in buildings is not widespread in Toronto, even though it is commonly used in Middle East, Europe, parts of the U.S. and Australia. Kokai explained that post-tensioning allows for less thick structural members and larger spans, freeing up interior spaces in a building for the developer to lease or sell. In Toronto, RJC has designed post-tensioned slabs, beam systems and transfer structures in projects such as the Waterpark Place Phase III office development. It uses a post-tensioned slab, supporting two additional floors hung from below that spans 27 metres in both directions and is only 1 metre thick, which Kokai said is “quite impressive.”

The panel is one of a series of three that CBTUH is holding in Toronto. The organization is also promoting its next conference which will be held in New York City on October 26-30, 2015 where tours of some of the newest skyscrapers are already planned.