There are two aspects to the design of the structure for this project. These are the adaptation of the existing building and the new-build section.
Adapting the existing building involved extending the columns to lower bases to accommodate the lowered ground floor, creating space for the lift shaft and air-conditioning main supply ducts, supporting the new roof structure, incorporating the large window overlooking the courtyard and various openings for the loading bay, bake-cure oven, etc. The existing structural steelwork frame dictated much of the design in the entire building, as the depth of the existing steel beams supporting the floor was adopted as the perceived depth of all steel beams below the floor. In some cases, this involved beams with a top flange level with the structural floor surface and shelf angles supporting the floor to give the impression of a complete beam below the floor.
The structure of the new-build section is reinforced concrete for retaining walls round the plant room and cinema and for the floor slab over the cinemas. Elsewhere a structural steel frame supports precast-concrete floor slabs.
The architect wanted the roof to appear to float above the clerestory above the walls, and did not want conventional heavy portal columns around the perimeter. To achieve this, the roof over both the existing building and the new-build section is supported by longitudinal trusses, parallel to the front and rear walls and set at 3.5m in from each wall. To result in as few columns as possible within the galleries, the trusses span 12m. The roof structure also incorporates triangular plenum spaces for air- conditioning flow and return.
Throughout the building great attention has been given to the details of the steel structure where it is exposed.
C C Moodie
Ove Arup & Partners Scotland