A STEEL-FRAMED GALLERY TO AN AUDITORIUM
The first-floor seating gallery and technical gallery above it are elliptical in plan; the gallery steel structure is supported on slightly canted 220mm-diameter CHS columns and enclosed with a screen of standard corrugated GRP roof glazing sheets.
The inner edge of the gallery structure is formed of curved 180 x 75mm PFCs. The outer edge is of curved 100 x 200mm RHSs welded on site to plate cleats fixed to the columns.
A series of UBs cantilevers from the columns to support the PFCs, and T-shaped beams run between the inner and outer edges to support an LVL ply floor. The steelwork is exposed, with simple acoustic soffit panels fixed between the beams.
The framework supports a row of cushioned two-person seats. The seats are fixed back to a raked balustrade of steel tubes and flats that follows the curve of the ellipse. A plywood ventilation plenum runs below the seats. To create the statutory passage space, the front edges of the seats flip up on gas stays.
The inner balustrade is a series of cranked steel-plate balusters that supports a 'soft' curved handrail - of timber wrapped in foam and clad with felt so that the audience can lean on it. Infill panels between balusters are of standard expanded steel mesh, a material that combines protection with visibility.
The mesh was rolled to remove sharp edges, allowed to rust and finished with beeswax.