One of the main structural challenges was to achieve the architect's vision of elegant 'tree structures', with branches that retained a naturally random appearance, to support the glazing which encloses the 8m high x 7m wide 'street' area. A structure which mimicked that of a tree would require large members, cumbersome moment connections and more complex foundations to cope with moments induced by horizontal and vertical loads.
The design that was developed involved triangulating forces in the branches, using strut and tie members in the plane of the roof, and fixing two branches back to the second-floor slab of the adjacent classroom block to give lateral support. The elimination of moments in the branches meant that they could be kept very slender. It also meant that pinned end connections could be used. The randomness associated with a natural tree was achieved by varying the springing points of the branches from the trunk. This induced small moments in the trunk but none in the foundations, which are simple mass concrete pads.
A similar approach was used for the tree structures supporting the main entrance canopy.
The two-storey music studio and computer building was much simpler, using a reinforced concrete flat slab at first floor level supported by loadbearing masonry walls. Occasional steel columns were needed to create large open spaces in the foyer and library area. A deep profiled metal roof deck was used to form the mono pitched roofs so that only one steel purlin was required over the 7m x 8m classrooms at midspan.
The same roof covering was employed for the multi-purpose hall. This consisted of a steel frame braced by masonry panels on strip and pad foundations.