Terri Meyer Boake BES BArch MArch LEED AP
Associate Professor :: Associate Director :: School of Architecture :: University of Waterloo

Renovation to the Art Gallery of Ontario

... the steel stairs

Frank Gehry Architect

Toronto, Ontario

 


Project Information:

Design Architect: Frank Gehry
Local Engineer: Yolles Halcrow
Steel Fabrication: Benson Steel, Mariani Metals
General Contractor: EllisDon
Cladding: Flynn

Gehry has used a series of curved steel framed stairs throughout the project. There is the main feature stair that rised up the centre of the building, connecting old Walker Court to the new top floors of the extension. There is a spiraling stair that sits outside of the glass wall on the south face of the building. There are also two other spiral exit stairs that will service the south facade.

Although I did manage to see inside the project in June, and can report that the feature stair is about 2/3 installed, photos were not permitted. I visited the shop of Mariani Metals in north Toronto, and have included some images of the steel stairs in production at the shop. The main stair requires some very complex joinery due to the use of bent steel tubes as its main structural support. Splicing the tubes on site is quite difficult as they tend to deform during bending, which is quite natural. The wall thickness of the tube is between 5/8" and 7/8".



Project Images: June 2007
The upper landing of the steel stair hanging from the south face of the extension.
Closer view of this landing. Note the open steel tube. This will be connected to the next section of the stair when it is lifted into place.
The main structure of the landing is in the form of a modified HSS truss system.
Cutouts in the WF beam to allow for the passage of services. You can see that plates have been added to reinforce around the cutouts.

Until all of the sections are securely in place, tension connectors support the cantilevered section.
A flatbed delivers two additional sections - parked on Beverly Street, waiting for site access.

Closer view of one of these sections.
As the steel will not be left exposed, you can see more serviceable welding techniques are employed.

A WF member is cut, ready for a connection.
View up the south facade at the upper landing.
Another truckload of segments.
The plate extension here will be used as a temporary connector that will hold the sections in place, so that the crane can be disengaged, prior to completion of the welds on the tubes.
View of teh same connection on the lower tube of the frame.
A plate attached that will be used for lifting.
The ends of the tubes are taped during painting so that the steel will NOT be painted, leaving it clean for welding. My hand here so that you have some idea of scale.
Close view of another of the connection points.
A couple more sections parked behind the project waiting to be lifted.
And more sections.
More stair pieces, August 2007
Support for a landing - as of August 2007 all of the sections of this stair are still waiting to be erected.
The section is supported on a steel frame in behind for temporary support/transportation.
View of some steel plate ribs that support the flat plate portion.
Detailed view.
Mariani Metals - June 2007
Feature Stair
Inside the fabrication shop. They are working simultaneously on a number of sections of the stair. This is the feature stair.
As the stair is only supported, hanging from the adjacent structure, at about 4 or 5 points, this steel plate forms a key part of the structural integrity of the feature stair. You can see two temporary lifting points in this view.
One of the feature stair pieces being prepped. The main tubes have been cut. The small plate type joists are laid on to the trapezoidal connectors, already attached to the tube. The large plate upon which the steps will be fixed, has not yet been bent.
As the stair involved a bent surface to affix the steps, the plates are cut into smaller trapezoidal sections, that are welded together, to allow for easier creation of a uniformly curving bent surface.
A view of one of the flatter bent sections.
Alternate view.
A landing for the feature stair.
View to the underside of the landing showing the support structure - round tubes with small vertically oriented steel plates to provide additional support to the main plate. Curved plate is also used around the perimeter.
A closer view of some of the cut tubular sections that must be joined via welding to their neighbour sections.
My hand again to give you an idea of scale.
Tubes cut and lined up ready to go.
View to the underside of part of a feature stair section.
Secondary Stair
Some of the sections of the secondary stair being worked on in the shop.
You can see that the detailing is quite different from that of the feature stair.

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These images are for educational use only and may not be reproduced commercially without written permission. tboake@sympatico.ca

Updated June 17, 2008