Art Gallery Of Ontario Gehry Designed Staircases

Location: Toronto, Ontario, Canada
Architect: Gehry Partners
Engineers: Yolles Halcrow
General Contractor: EllisDon
Vibration Control System Supplier: Gerb

The Art Gallery of Ontario (AGO) underwent a major $276-million renovation and expansion. Famed Canadian architect Frank Gehry lead the redesign of this institutional project located in the heart of the Toronto neighbourhood he had grown up in.

As the hallmark icons of the redevelopment, Gehry created a series of magnificent interior and exterior protruding spiral staircases.

One of these is a douglas fir-clad sculptural staircase that rises up the centre of the building, connecting old Walker Court to the new top floors of the extension and another is a spiraling steelclad staircase that sits outside of the glass wall on the south face of the building overlooking Grange Park.

HGC Engineering was originally called upon to do a baseline environmental noise assessment for the Gallery. Later we were also asked to assess the vibration response of both featured staircases in anticipation of large crowds using them to move freely between floors. There was some concern about the vibration impact of this activity on the stairs and the building structure.

We conducted finite element analysis of the proposed design and determined that adding Tuned Mass Dampers to the staircases would harmonically absorb the forecasted vibrations dynamics without requiring the stair designs to be altered in any way. We designed and specified the required Tuned Mass Dampers.

Upon completion of the the staircases, Halcrow Yolles, assisted by HGC Engineering, undertook a follow-up vibration response assessment of both the interior Walker Court and southern exterior Staircase in order to determine the performance of the vibration mitigation design installed in meeting the criteria set.

HGC Engineering measured the response of both stairs at the most cantilevered point on the stair under two simulations; first, with a series of heel drops to determine the natural frequency and damping, and second by having a person (85 kg) walk purposefully up and down the stairs to measure the acceleration response. The measured acceleration response was compared to the criteria provided by the AISC/CISC for walking on interior footbridges.

The measurements and analysis confirmed that  the vibration response of both staircase performed well within criteria.