Structural Engineering on Full Display as The One Rises Taller

A high-profile Toronto development has been attracting the attention of both engineering and architecture enthusiasts, with attention converging on the intersection of Yonge and Bloor, where Mizrahi Developments‘ The One is on the rise. Designed by UK-based architects Foster + Partners with Toronto’s Core Architects, the building has been generating plenty of buzz in the first few months of 2021, applying for a height increase that would increase the tower from the approved 85 storeys to a new 94-storey, 338.3-metre height. At 308.6 metres, it will already be the tallest building nationwide if it does not get the height increase it’s asking for, but if it does get the increase, it will keep that title after other Toronto supertall projects like the 312-metre SkyTower at Pinnacle One Yonge top out.

The One, Mizrahi Developments, Foster + Partners, Core Architects, TorontoAerial view of The One, image by Forum contributor Benito

The One also got some global attention this week, placing on Dezeen’s list of top ten of upcoming supertall skyscrapers with designs by international starchitects. As the conversation about this upcoming landmark builds, so too is the visual evidence of the complex structural engineering that will support the tower. The One’s hybrid exoskeleton system is supported by eight 40-tonne steel-core, concrete-encased supercolumns. After the project was issued long-awaited above-grade building permits in mid-2020, these supercolumns have been secured in place along with a lattice of steel beams and canted columns.

The above-grade rise has thus far included forming of the building’s flagship ~12-metre-high retail space, with a column-free ground floor that requires the spectacular structural plan above. With supercolumns and other structural elements now rising to the base of the seventh floor, other areas have had their skeleton etched out, including the restaurant and event spaces on levels three and four.

The One, Mizrahi Developments, Foster + Partners, Core Architects, TorontoAnnotated floors at The One, original image by Forum contributor Riseth

To accomplish a large, open retail space at ground level, the tower’s elevator core cannot go all the way to the ground, so it is to be ‘floated’ above the base levels. A separate bank of elevators is being built to the west that will shuttle people from ground level to the restaurant and hotel spaces of the podium floors, and a residential sky lobby on the sixth floor, from where they can catch an elevator up to their suite. The tower elevators’ pit will be built on the fifth floor, above a pad that will occupy the space within a grid of steel beams that currently surround the central crane. Currently, the south podium is having its fifth floor formed, while the west podium’s sixth floor is taking shape. 

The One, Mizrahi Developments, Foster + Partners, Core Architects, TorontoAerial view of The One, image by Forum contributor Benito

The One is to contain 21 elevators by Otis Elevator, with three different types of systems including “SkyRise” elevators which will carry passengers up the tower at speeds up to 12.5 meters per second. Four of these will be “SkyBuild” elevators, which are to rise as the tower is built, through its unfinished interior elevator shafts, serving construction purposes before eventually being converted into the standard SkyRise elevators once construction is complete.

The One, Mizrahi Developments, Foster + Partners, Core Architects, TorontoThe One, image courtesy of Mizrahi Developments

You can learn more from our Database file for the project, linked below. If you’d like to, you can join in on the conversation in the associated Project Forum thread, or leave a comment in the space provided on this page.

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