A steel structure supported by steel forked supports
The original roof of the silo building has been replaced with a new structure which houses a restaurant and cafe.
Its position above the original parapet allows views of the river and city. The enclosure is set back from the north and south walls to allow glazed laylights to run along the sides and give natural light to the gallery on the floor below.
The structure consists of an arched steel roof of 254 x 132mm UC beams welded at their ends to 254 x 132mm UC columns at 2.5m centres.The columns are positioned beyond the glazed walls of the restaurant on the north and south sides. Together with 254 x 132mm UC beams at eaves and base, they form Vierendeel trusses, one on each side.The trusses are supported by a series of stainless steel forked supports, six on each side, which run above the laylights.
The forked supports are welded to new column structures which act compositely with the original north and south walls.
Each forked support consists of six tapered stainless steel tubes stitchwelded in pairs to stainless steel castings with forked connectors.These in turn are pin-connected to the tops and bases of adjacent UC columns.
The other ends of the tubes are stitch-welded with two stainless steel castings to the 245mm diameter stainless steel column.
The tubes are made of high grade stainless steel for fire engineering reasons - to support the structure in the case of differential collapse.
The surface is bead blasted and sealed with epoxy resin to create a smooth surface and prevent pitting.
The arched roof is covered with an anodised aluminium rainscreen clipped to a standing seam aluminium roof covering.