In almost every new stadium constructed in the past five years, precast concrete has been the heart around which the structure has been built. The reason for this is that precast concrete elements offer a solution for all design requirements, including:
Early discussions with the precaster should, therefore, be an integral part of the design process to maximise the benefits of the use of precast concrete in a purpose-built modern stadium. Precast stadium elements are manufactured in high quality steel moulds or beds, which ensures they are both dimensionally accurate and have an excellent finish. Units can be prefabricated to a much larger scale and delivered precisely when they are needed in the programme. The units are generally craned directly from transport to final position therefore storage of materials on site is negligible.
A precast structure can be erected in a third of the time needed for a traditional building. Hollow-core flooring units provide:
Precast stairs and landings also help to provide immediate, safe access. Similarly, the terrace units, vomitories and step units are delivered to site for immediate positioning onto prepared bearings, either precast raker beams or steelwork. In every case, the use of precast concrete means that the structure can be released quickly and progressively to following trades while work continues with the erection of further precast elements.
In most newly-constructed stadia, the precast flooring, terraces and stairs are erected on a steel-framed structure. Given technical input from both parties of the design team, the combination of the two techniques, concrete and steel, leads to an efficient and economic design for the project.
Although no two stadia are the same, there are a number of elements that are required by all precast concrete designs.
Precast concrete hollow-core flooring is designed either simply supported or compositely in conjunction with the steel frame to minimise steel sections and thus save costs. Further advantages are:
Precast concrete stairs speed construction work and provide safe, immediate access routes between floors. They are easy to erect and quick to place, eliminating on-site shuttering and the delays that arise with site-cast concrete.
Precast terrace units are manufactured to suit the configuration of the steel or concrete frame needing only abutting joints to be sealed. Generally, terrace units can be designed and manufactured to a maximum length of 9m and are carried directly on location studs positioned on bearing stools welded to the raker beams. Spectator seating can be fixed directly to the terrace units without the need for further finishes.
Precast concrete terrace steps are grouted or glued directly onto the terrace units to provide ease of access. Vomitory sets are the supporting units which form the means of access from the rear or concourse areas onto the terraces. As with all precast terrace elements, the sets are manufactured in precision steel moulds, eliminating costly time-consuming site shuttering. Lifting points are cast in at the factory and make on-site placing quick and easy. Precast concrete walls are manufactured in adjustable steel-faced moulds that can easily accommodate changes in length, height and thickness of unit while retaining accuracy and product finish.
All of which points to precast concrete as the logical choice for stadium construction.
MPA Precast is part of the Mineral Products Association, the trade association for the aggregates, asphalt, cement, concrete, dimension stone, lime, mortar and industrial sand industries. www.mineralproducts.org
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