Prestressing specialist Freyssinet has supplied and installed the post-tensioning system on the new £429M Royal Liverpool University Hospital, which is being constructed adjacent to the existing hospital building and is due for completion in 2017.
The project will be the largest all single-bed hospital in the UK with 646 beds including a 40-bed critical care unit, 18 operating theatres and one of the largest emergency departments in the North West. Carillion will build and operate the hospital on a 30 year concession. A new research facility, the Liverpool BioCampus, will be built on the site of the old hospital building as a key part of the city’s Knowledge Quarter.
The shape of the building is dictated by the completely different spacial needs of clinical areas, which form the lower four levels, and the eight floors of ward area which sit on top. This gives rise to the building’s distinctive 9m cantilevers at four locations on the façade. Level 4 is a massive transfer structure comprising 1750 x 2750mm deep post-tensioned beams cantilevering the 9m. Away from the massive cantilevers, transfer beams drop to 1800×2100 deep, 2000 deep and 1500 deep PT beams to suit the loading. Between these main beams run a network of 1250 x 1250mm RC transfer beams which pick up the ward column grid and transfer it to the clinical grid below. Clinical slabs are 350mm thick and span 8.6 x 7.7m. Ward slabs are 300 or 400mm thick depending on loading, on a grid of 8.0 x 7.6m. Recesses of 40-75mm depth are formed in the top surface of the structural slab.
The PT system is the 4B15 bonded flat duct system in the slabs with 19C15 multistrand tendons used in the transfer beams. The latter are stressed in stages to control deflections as more superstructure floors are added. Total PT slab area is 80,750m².