Micheal O’Keeffe
Principal
Glotman Simpson Consulting Engineers, Vancouver

A Delicate Balancing Act, Executed With Hard Science

Vancouver House is challenging engineering norms in North America and further afield. The unique tower transforms as it rises from a restricted triangular base, branching out into fuller floor plates as it ascends to its ultimate height, reclaiming efficiency and increasing its floor space for living. As the tower ascends, its floor plate increases from 725 to 1,226 square meters, while its north face increases in width from 1.8 to 30.5 meters. The inherent geometry of the tower and the offset nature of the core and walking columns pushes and pulls the tower over its height, subjecting it to sustained lateral and torsional forces under its own gravity loading.

To counteract the challenges of the tower’s complex form and the region’s high seismicity, a flexure- and torsion-resilient core is implemented as the rigid spine of the tower. Wing walls extend as outriggers from the northwest and southwest corners of the offset core, staggering their openings between the two walls on every floor. At the extreme ends of the wing walls and furthest location from the core, post-tensioned high-strength threaded rods counteract the primarily unidirectional loading of the tower, pulling the building back to near verticality. Ultimately, the residual set of the structure was analyzed to confirm near-elastic performance under 1.0x maximum considered earthquake (MCE) and vertical stability and safety under 2.0x MCE.

Employing a reinforced concrete core, utilizing innovative systems that had never been used before in the local residential high-rise construction industry, and undergoing stringent performance-based design analyses above and beyond current practices and codes, showcases the possibilities for what can be achieved in an industry generally more accustomed to regular rectangular box structures.

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