Main engineering feats
Tall buildings come with their own special set of design challenges, and Stantec Tower is no exception. It’s height and tight footprint were ambitious but designing a mixed-used tower to include commercial, retail, and residential space was even more demanding. This project was the first chance for many of our team members to come to grips with these question marks—and they relished the challenge.
Foundation: It’s only fitting to start at the bottom with Stantec Tower’s record breaking, three-metre-thick (10 feet) raft slab foundation. At more than 2,800 cubic metres (3,062 cubic yards), it was the largest continuous concrete pour to ever take place in Edmonton and took more than 300 trucks, 4 pumps, and 10 hours to complete.
Although working on the tallest tower in western Canada was a great experience, the lasting takeaway for me was the teamwork.
Because of Stantec Tower’s considerable height—and poor bedrock in Edmonton—the design called for more support in the form of piles. Piles are massive concrete columns set deep into the ground. Stantec Tower’s piles go as far as 80 metres beneath the surface—that’s deeper than the piles of the world’s tallest building, the Burj Khalifa!
Stabilization & outriggers: Whereas foundations give skyscrapers strength, the concrete core walls provide stability. When a tower becomes too tall, conventional concrete core walls are not stiff enough to withstand the wind. So, Stantec Tower implements steel outriggers to help make its height possible, providing support and preventing the top floors from swaying back and forth too much. That way, occupants won’t feel sea sick on a windy day!
So far, there is nothing else like this system in Edmonton—stabilizing these structures is no easy task! Every metre of the material weighs 1,000 kilograms (2,200 pounds). That’s about twice as heavy as a grand piano.
The transfer slab: A transfer slab is set right at Stantec Tower’s 30th floor, 122 metres (400 feet) into the sky—another engineering and construction achievement that’s never been seen in Edmonton before. The two-metre thick transfer slab encases the last of the steel outriggers and allows for flexibility on floorplates that require more or fewer columns.
The transfer slab (also known as a sky raft) caps off the commercial partition of the tower and marks the beginning of construction on the residential portion of the building. The floor will serve as an amenities space for SKY Residences and feature an outdoor patio and lounge area.
