A PRECAST-CONCRETE STAIRCASE WITH A STEEL BALUSTRADE
The three-storey office building has a central atrium flanked by landings which give access to open-plan work spaces. Precastconcrete staircases rise through the atrium space, placed asymmetrically for 'a dynamic contrast to the building's stringent 6m column grid'.
Each staircase, with treads and risers only 150mm deep, rises 3.37m and spans 7.35m from one side of the atrium to the other. To achieve the span, CRC (high-performance steelfibre-reinforced concrete) was used. The staircases were cast in timber moulds in a vertical position, so that only one of the short sides was handled.
The top and bottom treads of the staircases are extended and 'float' over the atrium landings, supported on steel spacers. Balustrades to landings and staircases are virtually identical. They consist of a series of 80 x 15mm steel flats welded to form a frame; the intermediate vertical flats extend above the frame to support a tubular hardwood handrail. Two rows of 10mmdiameter steel rods pass through the intermediate steel flats and are bolted to the end flats with round-headed bolts.
The landing edges are clad with 10mm-thick steel fascias, bolted to the edge beams with round-headed bolts. All bolted connections are of exposed polished stainless steel to contrast with the grey-painted fascia and balustrade steelwork.