3 St Paul's Place

Extended aluminium fins frame each double bay of the elevation to express the structural grid of the upper steel frame. The double transom arrangement at floor slab edge frames an anodised aluminium spandrel panel that covers the floor slab edge with the remainder of the ceiling depth, cloaked by a white PPC aluminium pressing fixed to the back of the lower mullion. Roller blinds are positioned behind in a recess obscured by the plasterboard margin and help to mitigate solar gain.

The greater depth of the in-situ reinforced concrete frame to the cantilevered first floor is enveloped by natural anodised banding and the soffit is underdrawn with BluClad board, which is finished with a high build-up paint to create a seamless surface to the soffit over the entrance colonnade. In-situ reinforced concrete columns transfer the loads back down to the pile capping beam below ground. The columns are tapered to front to help minimise the depth of transfer structure required and negotiate the oversailing condition to the front entrance.

A steel frame structure was chosen for the office levels above first floor. Through the use of long span beams the internal columns could be eliminated to provide a clear, open-plan office space around the central core. The use of cellular beams allows for services integration within the structural zone in order to keep the overall floor depth and storey height to a minimum. The beams are designed to act compositely with the concrete floors slabs to deliver an efficient and economic frame. Stability is provided by the concrete shear walls around the central lift and stair core. 

A key feature of the building is the exposed concrete columns at ground level. These support the perimeter steel columns above and are inclined outwards in order to reduce the requirement for transfer structure at first floor. The decision was made to adopt an in-situ reinforced concrete frame up to first floor level as it was considered that this would best resolve the lateral forces due to the inclined columns and the transfer requirement at first floor.