The driving principle for the design of the structure has always been lightness and slenderness, to contrast with the mass of the original Spence buildings and to help define the new interventions.
Each school's entrance building has its own arrangement and programme, requiring different structural layouts. To achieve an economy of means, and to develop a common language for the project, a kit of parts has been devised; slender columns pulled away from walls, free-spanning curtain walls, flat metal-clad roofs folding into walls, and free-standing canopies.
The primary structural material used throughout is steel, with infill timber joists forming the secondary structures within floors, walls, and roofs. Detailing of the frames has been kept deliberately simple, allowing fabrication and erection to proceed economically within the tight programmes imposed by university terms. Given the proximity of the new entrances to the existing teaching buildings, site access and noise were major constraints on the design.
The pavilion structures are simple braced boxes, constructed of simple steel 'sticks', and partially supported by and integrated within the existing concrete framed buildings. The walkway structures are supported by fixed-base columns, to ease erection; the columns acting to resist lateral forces like blades of grass in unison. All external steelwork is galvanised and then painted to minimise future maintenance costs for the university.
Other than foundations, which are simple mass concrete pads on the chalk, the only 'wet' structural elements are the horizontally boardmarked in-situ concrete monoliths that form part of the identity of each school.
The theme of lightness is also expressed in the staircase within the first completed building, much to the consternation of the Estates Department. A folded steel plate with timber treads mimics the structural principles of the Georgian stone staircase.
Bob Barton, Barton Engineers