Fisher Engineering Ltd (Severfield-Rowen Plc)
Bam Construction Ltd
Leeds Metropolitan University
The Rose Bowl provides Leeds Metropolitan University with a landmark, easily identifiable building.
Central to the project is the Rose Bowl lecture theatre ‘pod’ which sits ‘half in and half out’ of the atrium and contains one 250-seat theatre, two 140-seat and four 60- seat theatres. As well as having an unusual oval bowl-like shape, tapering outward as it gets higher; the structure is clad in distinctive triangulated reflective glass panels fixed to a bespoke aluminium backing frame system. A series of bridges crosses a semi-public atrium linking the ‘pod’ to the outer U-shaped four-storey main floorplates, which house the offices and ancillary teaching spaces.
The building is built over a two to three storey basement car park which extends significantly beyond the footprint of the building. The sloping site introduces a full storey height difference across the building with access at ground floor into the central atrium beneath the ‘pod’, and at first floor directly into the building and on into the main lecture theatre. From ground level up the structure is steel framed to provide maximum flexibility to the floor plate. Cellular beams were used to allow the coordination of mechanical and electrical services into the void. Clear spans of 15 metres are found throughout the building with perimeter columns set back into the space to create a clean façade. The whole of the steel frame rises off the concrete basement columns and transfer structure located within the ground floor slab.
The outer four-storey faculty block and two-storey plant enclosure were erected in phases to facilitate access to working faces. The faculty building steelwork was initially erected up to third floor level and then used as a working platform for the operation of MEWPs to allow the safe erection of the remaining steelwork to the upper levels.
The pod structure itself consists of a series of Y-shaped feature columns connected to a circumferential truss, or diagrid, extending around the envelope of the pod. Temporary stability during pod erection was ensured by tying the circumferential trusses back to the four internal main columns, which were in turn temporarily tied together to form a central braced core.
The ring of Y-columns at the base required a 100 tonne mobile crane, as each of these columns, brought to site as complete pieces, weighed around 5.5t. The first column to be installed was held in position using the crane, and then the adjacent columns were installed using a second crane and tied together with a beam to provide stability. Once the first two columns were installed and stabilised, the entire ring of columns was completed by tying them into adjacent members and the central braced core.
Once the central core and ring of Y columns were in place, the steel diagrid and floors were erected using the temporary core to control the position of the diagrid and provide stability. On completion of the diagrid shell to third floor level, the concrete deck was poured and the pod became self stable. The remaining diagrid and floors were then installed and the temporary bracing removed.
Fabrication of the Y-shape columns and diagrid members required extremely high levels of accuracy to achieve the necessary tolerances. The Y-shaped columns are complex sections fabricated from individual plates of varying thicknesses of between 20 and 55mm. Each “Y” consists of three tapered branches of triangular section which increase from approximately 350mm in depth at their tips to about 450mm at the central node.
All of the individual plates were blasted before fabrication with the completed assemblies blasted again prior to painting. All steelwork then received intumescent fire protection, including the Y columns to ensure that the optimum level of fire resistance was achieved.
This university development has three teaching blocks, but the interest is in the splendid ovalshaped structure in the centre.
Tapering outwards as it rises, the Rose Bowl’s frame is supported by Y-shaped two-storey triangular columns, which have been designed and fabricated with crisp corners. The overlying storeys are carried by a vertical diagrid, with elegant bolted connections.
The careful detailing and fine fabrication are commendable.