Swimming pool in Vichy

Famous throughout the world for its spa activities, the Community of Vichy has boasted major sporting and cultural infrastructures since the 1960’s. The new Vichy swimming pool forms an integral part of these. Combining multiple sporting and games activities, it is characterised by the use of an innovative technology, stainless steel swimming pools.

The site on which it is built is located along the Gannat road, the main access road to the City of Vichy from the motorway. From this position, where it dominates the Allier Valley, the city and the racecourse, it enjoys an unrestricted view over the countryside.
The project consists of two main volumes: a main building called the “Blue dome”, intended for play areas, and a triangular space comprising changing rooms, sanitary equipment and areas intended for sporting activities. Access to the swimming pool is gained by following a covered main axis that also enables the different areas and spaces to be arranged. From the car park a thermal water spring extends along a path to a rotunda (reception area), ending at the “Blue dome”, which opens out onto the outside swimming pool. To the south is the open air Olympic swimming pool and the restaurant, and to the north, the facade of the technical areas behind a screen of vegetation.

Stainless steel swimming pools
The programme comprises a total of five different pools. First of all an outdoor Olympic swimming pool measuring 50 m x 21 m, surrounded by beach areas for games and terraces. Then there is a covered pool of 25 m x 21 m with terraces and seats. And finally the “Blue dome” pools containing a learning pool, a play pool and one intended for children. A total of 65 tonnes of stainless steel were required to construct 2150 m² of water area.
The stainless steel pools consist of a bottom and side walls of 1.5mm thick metal sheets. The sheet on the bottom rests on a platform consisting of a compact ballast. The walls are welded and supported by a stainless steel structure made to measure, which ensures the stability of the pool.

Advantages
The use of stainless steel in a swimming pool provides numerous advantages:
- Provided that the appropriate grade is selected, this material is wholly suited for use in a swimming pool.
- Stainless steel is a resistant material whose appearance does not alter with time.
- In daily use, and provided that the instructions issued by the manufacturer are followed, the stainless steel surfaces are very easy to clean (by rinsing in clear water).      
- This material is harmless to the environment and is naturally hygienic: in particular, it prevents the growth of bacteria around the tile joints.
-The structural system is extremely efficient: self-supporting down to a depth of 2.2m, with reduced weight and  held in both new and renovated structures, guaranteeing above all perfect sealing thanks to the assembly system of the sheets, which are welded together.
Finally, the stainless steel solution extends service life compared to traditional pools, with less maintenance and at a comparable construction cost.

Structure
The structure of the “blue dome” is 41 metres in diameter. It is formed by semi-arcs consisting of HE 180 section beams, with underlying cables of galvanised steel 20mm in diameter. The “triangular” structure, which includes the rooms and sports pool, consists of HE 280 main beams with a centre to centre distance of 5.20 metres. These beams have a span of 9 metres, except for the sports pool, where their span is 33 metres and where the beams are trussed by cables 2.30mm in diameter. The total height of the mid-span beams is 2.50m. The structure covering the service rooms and the restaurant consists of IPE and HEA double slope beams.
The service buildings are sealed by a bitumen covering and the swimming pool roof is constructed with an “acoustic” perforated steel trough.

In most cases the main beams of the structures are supported on steel posts. The beam supports are articulated.
All the frames have been constructed with steel with anticorrosion protection by hot galvanisation both for the blue dome and in the “triangle” and restaurant.
In the actual structure of the building project completion periods were reduced thanks to the prefabrication and pre-assembly of the steel pool elements, which also guaranteed better operating quality.

Text: Constructalia