Bearing Up
Ground-floor extensions
1 Precast long-span waffle-slab floors (click to enlarge)
2 Building supported by racking steel struts (click to enlarge)
The Rankine Brown building's southern-end foundations were stepped in from level 2, ground level, to level 0. The university was keen to expand the library space; so the second-floor slab, which was sitting on fill, was demolished and fill removed to create 1000sqm more floor area. [1]
Meanwhile the above-ground weight of the southern end of the building was supported by racking steel struts [2] between the suspended floor junctions and the southern columns – which ended abruptly in midair at what was previously ground level. [3] New reinforcing cages on the bases of the southern columns prepared them to meet their lower counterparts, which were being built up from level 0. The horizontal beams through the first and second levels were modified to take the new suspended floors, which will extend to match the podium “footprint" above.
Before excavation began, the boilers were temporarily removed from the level 1 slab-on-grade plant room, and hot water provided from a container-mounted boiler at the northern end of the building. The new level 0 plant room with articulated pipes started operating on time on 1 April. New stairs linking levels 1 and 2 are to be installed at the southern end, with the potential for extension to level 0. The stairwell area has been designed by Athfield Architects to include harbour views and conversation areas.
