A glazed facade with 'kipper' trusses
The three-storey terminal building is covered with a sinuous curved and vaulted roof, supported internally on pairs of canted columns. It extends over the glazed north and south facades to shade them, propped on external canted Y-shaped props at 18m centres.
The glazed facade and its 'kipper'truss support structure were designed to be minimal and delicate, so as not to break the flow of the roof, inside to out. The trusses are tensioned to resist wind loading and formed of five horizontal cast stainless steel arms connected by pairs of stainless steel rods. The disposition and varying lengths of the arms create the fish-like shape (hence the name) and reflect the line of structural forces.
The kipper trusses run at 9m centres, aligning with the main roof beams. They are pinned to the bottom flange of the beams with forked connectors and anchored at their bases to a posttensioned concrete edge beam.
Each arm of the truss supports a transom, a set of paired 76mm diameter CHSs, bolted together with welded flanges and clad with profiled aluminium. Each transom, in turn, supports three 2.34 x 3m long double-glazed panels. Two stainless steel drop rods at 3m centres between the kippers take out vertical deflection from the transoms - 75mm gaps were left between the glass panels to accommodate rotational movement. They were sealed with a concertina-like extruded rubber gasket.
The trusses were factoryassembled, delivered to site and loosely pinned and bolted. A set of ties and jacks were set up behind them and tensioned to draw together the roof and floor beam to a maximum loading of 60 tonnes. The trusses were then attached, tested and loaded to 40 tonnes. The maximum horizontal movement of the facade will be about 15mm.