A SLOPING ROOF WITH CRANKED BEAMS
The atrium space, 6.6m wide and over 46m long, is a place for informal meetings and seminars, like an internal 'town square'. Lecture rooms and cafés open off it and, as it is two storeys high, rooms at upper levels look out over it. With no external walls, the roof had to provide daylight and ventilation; running above each of the two long side walls is a continuous strip of doubleglazed panels which washes them with natural light; glare is avoided by a continuous solid insulated panel at the centre.
One of the long side walls (the left wall on the key crosssection) is a party wall and planning constraints limited the roof profile to a gentle slope upwards from it, matching the roof of the original building.
To demonstrate the fact that the sloping structure is equally supported, rather than a 'lean-to', the steel support beams, which span across the 6.6m width at 2.4m centres, are exposed and cranked.
Each beam is purpose made from three 210 x 267mm UB sections, with the lower flanges removed. The side sections are tapered and the central section is stiffened.
The glazing and insulatedpanel system rests on a series of UBs and channels fixed to the cranked beams. The strip of insulated panels conceals a gantry which slides above it on a track running the length of the roof, allowing all parts to be cleaned and maintained.