Buildings Award of Excellence
CIBC Square at 81 Bay Street RJC Engineers
Working within constraints The tower features unique floor plates to support its folded glazed façade, sloped building columns, a reinforced concrete core and a structural steel floor slab system. All floors are identical, except for varying edges to support the unique architectural appearance. Large corner cantilevers in the range of 4.5 m, which meet the architectural form, were checked by RJC for vibration with time-history analysis. Slender, 24-m tall columns in the main lobby, supporting the whole tower and bracing a 24-m cable wall, were made of 700 x 750-mm solid structural steel square sections. Many of these highly loaded structural steel columns were tilted to 26
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“A huge building in a very tight space, over one of the busiest travel hubs in Canada. Not an easy site to work on.” Jury
avoid the architectural services below. A seven-storey podium implements an intricate stacked-occupancy scheme, including securities trading floors, amenity spaces (restaurants, retail, conference facilities) and a mechanical and electrical level just above the new two-level bus terminal. The geometric constraints required creative designs using structural steel beams and full-height transfer trusses, reinforced concrete and post-tensioned concrete systems. The tower and podium were structurally hardened beyond CSA standards. A 900-mm deep post-tensioned slab supports the upper bus level and spans 24 m over the lower bus level. The shallow depth of this slab was critical in accommodating appropriate floor elevations dictated by path
access and bus ramp slope criteria. The 1.5-acre elevated park connects the development to the north side of the rail land, creating a new public realm and setting a new precedent for future developments over the 16-track rail corridor. Its geometry required long-span steel trusses for strategically located columns for future train tracks. All tracks were opened during construction, which made field operations complex. Another key element is the 40-m long Bay Street Bridge, with a fullheight glass wall on the south side (no structure), spanning Bay Street. The ‘open C channel’ structure required complex analytical modelling to optimize stresses for a cost-effective design that carefully considered accelerations due to walking vibrations. Excavation and construction of a
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IBC Square at 81 Bay Street is a commercial office development in downtown Toronto’s financial district, just north of the Gardiner Expressway and adjacent to Union Station, the Path and Scotiabank Arena. With its many connections, it is one of the most complex and advanced towers ever constructed in Canada. Rising 54 storeys, it offers 1.5 million sf for office space, restaurants, retail stores, a terraced park platform and a new GO bus terminal. RJC Engineers provided structural engineering, along with CSA S413 waterproofing consulting for vehicular traffic surfaces, for this complex development.
September/October 2021
2021-10-18 10:14 AM
