Amid the bright colour and frenetic architecture that typifies much of the Dome's interior, the Talk Zone's clean lines and etched glass walls bring a refreshing lightness.
Designed by Imagination for sponsor BT, the Zone's two linked 40m high buildings have a 'black box' interior housing the exhibitions and fully hung glazed facades offset by 1.2m to give a 'deep picture frame' effect. During design development, Imagination added large atria at each end of both structures to increase the essential 'wow factor'.
A wide range of constraints had to be overcome to fit both buildings into the tight 19m by 65m footprint. A large garage used for the Dome's central show lies below one building; a main service route passes under the facade; the central promenade is uncomfortably close; and no extra load could be transferred onto piles supporting the adjacent mast.
Structural engineer Buro Happold chose to split the cores and the facade into two separate phases. The phase one cores are stiff steel boxes with braced steel frames aligned with the Dome's radial lines to create the curved inner and outer facades.
The secondary steelwork - supplied and erected by Sheetfab - supports the glazing panels and transfers their load back to the core structures. The entire 2,300m2 of glass is hung from the top of the building, with continuous curved eaves trusses on the long sides taking much of the load.
The atria structures are suspended from eaves-level prop and tie steels cantilevered from the phase one corner columns. Stiffness is achieved by roof level bracing, and by designing each of the service walkways as horizontal portal frames.
Design of the phase two steelwork had not been finalised when the primary steelwork had to be procured. Buro Happold project engineer Ken Jones says: 'The Phase 1 structure had to be sufficiently flexible and strong for anything to happen in Phase 2.'
However, it was impossible for fabricator Hare to match the tolerances needed for the glazed facade. Each of the glass panels is designed to fit within a tolerance of just +/-2mm. Phase two steelwork and fixings that hold the glazing panels had to be designed so they could be adjusted in every direction when the glass was fixed in place.
Structural and M&E engineer: Buro Happold
Steel contractor: Sheetfab