The association for the manufacturers of architectural cladding and structural precast concrete

Creagh Concrete

Case Studies ›

With its head office in Northern Ireland, Creagh Concrete’s core products are precast and prestressed flooring, each with unique properties designed for commercial or residential applications. Recently, the company completed work on a multi-storey car park for Blackpool’s Victoria Hospital for the NHS Trust. The six-storey 1001-space structure has a footprint of 11 bays 7.2m long and three perpendicular 15.7m bays.

The brief was to provide a concrete car park, constructed to a good level of finish and detailing a contemporary, yet functional external finish, without the need for unnecessary cladding. Particular attention was given to the southern elevation of the car park as it can be seen from the main entrance of the hospital.

 

The single wide-span vehicle access ramp is roughly in the middle of the building, with a movement joint alongside to subdivide the structure into two parts. There are also two stair cores, one at each end of the building. A key design element was that all proposed materials and details should be selected for their long-term durability, low maintenance and aesthetic appearance. Perimeter spandrels are therefore not only key load-bearing members but also provide a smooth, uninterrupted feature band along the façades. This is further enhanced by forming all the spandrel panels to a high standard of finish using a white concrete mix.

 

 

 

 

 

 

 

 

 

 

 

Walls were generally produced as single-storey precast concrete elements, with the precast walls used to form the two stair cores. To provide lateral stiffness, they are also positioned along the centre-line of the building.

 

Typically, inverted T-beams – exclusively in precast concrete, with a reinforced section to minimise the amount of temporary propping required during the deck construction – span between columns.

 

Spanning between the main deck beams and/or the perimeter spandrels are 400mm thick prestressed hollowcore slabs; these are tied to both the beams and spandrels at the ends and act compositely with the structural topping. With a clear span of 15.5m, the hollowcore slabs cover more than 24,000m2, and if laid end-to-end would stretch to 11.4 miles. As the client specified that applied finishes requiring ongoing maintenance should be avoided, all deck slabs have a brushed in-situ concrete topping.

 

Stair flights spanning between each landing are tied at their ends. They span perpendicular to the flights and are supported by precast walls via concealed connectors. The landings are also tied to the supporting walls.

 

 

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Simply supported between either columns or walls, spandrels have a projecting nib to support the main deck slabs, and a notched end connection integrated into the supporting corbel to provide a flat soffit. To avoid torsional stresses, slab ends are anchored to the spandrel via coupled reinforcement concreted into the ends of open cores in the slabs. The top stem of each spandrel also acts as a vehicle impact barrier around the perimeter of the car park edge.

 

Columns were produced as multi-storey precast concrete elements, with projecting corbels to support the edge spandrels and internal main beams. Typically cast in three-storey lengths, they were designed to be braced and are tied to the deck at each level.

 

 

 

 

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