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Delta Frames

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Delta Frames

Queen Richmond Centre West, or QRC West, developed by Allied Properties REIT and designed by &Co. Architects, is destined to be a landmark in Toronto’s Entertainment District. Due for completion in mid-2015, QRC West will impress with its innovative and smart design features, especially in abundance in its L-shaped atrium/lobby which we shall focus on today, but also for less obvious features that include fully-automated daylight harvesting, a glare control system with external solar shades and internal automated blinds; 18” pressurized raised floor system with under floor air distribution, suitable for hidden modular plug-and-play voice, data and power cabling systems that simultaneously improve indoor air quality.


Rendering of Queen Richmond Centre West, image courtest of &Co. Architecs

Targeting LEED-Gold certification, QRC West continues the trend employed across the city of adaptive re-use of old with the new. The glass-clad 11-storey building will stand above the current 4-storey century-old masonry building currently on the site. While the exterior design and details are technically impressive, even if the classic Modernist box design is considered monotonous by some, much of the excitement around this development is due to the beautiful and ingenious “delta frames” that will be supporting the new building above the historic structure, creating a 70 ft. high atrium int he process. These delta frames are currently being assembled on-site by construction crews.


Delta frame with scaffold, image by StructEngGuy

Toronto firm Stephenson Engineering Inc. collaborated with Cast ConneX, also of Toronto, which specializes in designing cast steel structural components, to design an elegant support structure for the 11-storey office space of QRC West.

Cast ConneX, with design-assist from Walters Inc. of Hamilton, designed three hourglass-shaped space frame supports dubbed “delta frames”. Each of these frames compose of eight support members, with all members connected by a 35,000 lb. cast steel node 30 feet in the air.

The members too are cast steel, with a diameter of 1 meter and a thickness of 50mm. Due to manufacturing limitations, cast steel tubes are not fabricated in thicknesses greater than 50mm. This restriction means that the support member and node sections of the delta frames have to be filled with concrete to meet composite strength and stiffness requirements.

Aside from a reinforced concrete stair and elevator core, these three delta frames are the only structures supporting the 11-storey office space. Each of these delta frames are engineering to support a mind-blowing 80 meganewtons (approx. 18 million pounds) of axial compression.

We will return to bring more up-to-date shots of the site, but in the meantime to find out more about QRC West, visit our dataBase file, linked below. Want to get in on the discussion? Choose the associated Forum thread link, or add your voice in the comments section on this page.