To lure visiting patrons below grade, the descending experience must be enticing. The Onassis Cultural Center staircase is another engineering all-glass marvel on Fifth Avenue in New York City.
The middle landing is completely unsupported, cantilevered. The vertical stringers are a unique fabrication challenge of 4- ply, SGP-SentryGlas structural laminate. One end of the ‘tabbed’ treads are supported by ‘mail box slots’ in the middle wall. The other end of the treads are supported by a 2-ply sawtooth stringer, laminated to the face of a 2 ply. The total is a 4-ply laminate, massive, center wall.
This all-glass staircase is an engineering marvel of standing tension.
AGNORA worked extensively on internal R&D, enhancing certain requisite skills, tools and materials specifically for this project. The edgework of the SGP heat treated laminates are butter-smooth (without unacceptable post-laminate polishing).
The thickness and weight of the glass were critical with all vertical load bearing parts of the staircase comprised from either 3 or 4-ply heat treated 12mm (1/2”) thick glass and all horizontal components are annealed. The staircase treads, for example, are 4-ply and the landing is all 5-ply glass. the total 4-ply laminate, massive, center wall, weighing in at 1130kg (2500lbs)
AGNORA worked extensively on internal R&D, enhancing certain requisite skills, tools and materials specifically for this project. The edgework of the SGP heat treated laminates are butter-smooth (omitting all unacceptable post-laminate polishing). The alignment of the hardware fabricated holes and two / four ply laminates are accurate to a world class level of glass fabrication.
The largest and most complex section of the staircase is the central wall. This measures 2915mm (115”) x 4450mm (175”) and uses 4-ply 12mm (1/2”) thick Starphire heat treated, low iron, extraclear glass and two layers of 35mil (0.89mm) thick SentryGlas® interlayer. The glass for the central wall alone weighs 1130kg (2500lbs). “All vertical load bearing parts of the staircase are made from either 3 or 4-ply heat treated 12mm (1/2”) thick glass and all horizontal components are annealed. The staircase treads, for example, are 4-ply and the landing is all 5-ply glass. utterly important,” adds Mr. Moreau.
AGNORA worked closely with two engineering partners on the project, Michael Ludvik Engineering, the design engineer and Eckersley O’Callaghan, the review and installation engineer. Both companies performed a number of critical structural engineering calculations on the glass staircase, including tests to verify if the resistance of the annealed treads meet specific ASTM requirements.
The staircase also had to meet New York City building performance code regulations, which provided specifications on aspects such as the height of the glass balustrades and the distance between handrails and treads.
About the Onassis Cultural Center The Onassis Cultural Center NY explores Hellenic culture, from antiquity to today, through a rich and diverse program of exhibitions, events and online engagement. The newly renovated creative space in midtown Manhattan, designed by Perkins Eastman, presents a season of events where audiences can engage with art, ideas and culture.
"We felt as though we were creating a piece of art rather than a glass staircase." - Louis Moreau, AGNORA