Spectacular stair supported on 12-metre-long single-span glass balustrade beams with innovative laminated-in tread fittings.
This store is housed in a 1930’s concrete framed building on Jungfernstieg. The building required structural alterations to remove existing floor structures and strengthen the existing facade as a result of the floor removal locally to the facade.
Eckersley O’Callaghan were responsible for assessing the existing fabric of the structure and providing a detailed design of how the modifications could be achieved. This involved strengthening existing concrete structure with steel plates and justifying the existing structure for additional loads where required.
Development in glass fabrication technology has enabled a number of Apple projects to adopt larger format glass. The proposed stair in Hamburg was the latest development of this concept where each stringer of the stair was designed as a single laminated beam spanning 12m from the top to the base on each side of the treads. In addition to this, the concept of laminated fittings was taken a step further where each of the tread support fittings was laminated in to the panel and does not reach the outer face of the glass, maintaining a consistent reflective surface.
Each stringer is a laminate of 5 x 12mm thick heat strengthened glass panels, the laminated panel is 12 long, cranked for the half landing, and weighs in excess of 4 tons. In the same vein, each of the glass balustrades is fabricated as a single laminated panel to avoid the need for vertical joints. A unique system of ‘push to connect’ fixings were developed to allow each of the balustrade glass panels to be mounted without the need for fixing from the front allowing the stores interior finishes to progress ahead of the glass installation.
Bohlin Cywinski Jackson