When Michael Schumacher races his Ferrari round the 5.5 km long Shanghai circuit, he probably won't be aware that the track rests on a dense matrix of 40,000 prefabricated concrete piles. Like a large-scale version of the bed of nails of an Indian fakir, the piles measuring 25 x 25 cm were driven 25 m into the boggy subsurface, with little distance between them. The new race track is located northwest of the Chinese metropolis in the district of Jiading, a marshy region of the Yangtze River Delta, and was opened last year. According to a member of staff of Tilke consulting engineers in Aachen, the ground is so swampy that it is barely able to support a person walking on it. The conditions at the Fuji Speedway in Japan were similar. Here too, ground piles were used.
Each pile consists of two 12.5 m long segments that were driven into the ground in two successive shots using a pile driver. After the first shot, the segments were welded together via steel brackets fitted to the top of the first segment and the bottom of the second segment. Jacking then continued down to the specified foundation depth.
The heads of the piles are flush with the upper edge of a 50 cm thick gravel drainage layer, on which flue dust was placed as a levelling layer.
More than 343,000 cubic metres of EPS blocks were used to construct a 'landscape' with a thickness of up to 7 m on top of this base. The huge quantity of closed cell rigid foam required led to a temporary shortage on the Asian market. The actual track surface was constructed on top of this layer.
The large number of foundation piles required undoubtedly made prefabricated concrete components the only choice. For the grandstands, a second aspect was very important, i.e. uniform quality of the exposed concrete surfaces. This would have been impossible to achieve in the same way using in-situ concrete shuttering. Moreover, for Tilke as international engineering consultants it was very important to achieve a uniform quality standard across all their projects around the globe. For the engineers, the direct relationship between labour costs and the application of prefabricated components is significant. While in Europe, Japan or the USA prefabricated components are often used for substructures such as columns or stair trusses, countries such as China or Bahrain are considered to be almost "in love with in-situ concrete". In these countries, prefabricated construction is often not cost-effective, since the costs for additional logistics and design effort tend to be far higher than the costs for on-site construction.
For the projects described here, a mixed construction method was used. All planar or visible components such as roofs or grandstand steps were constructed using prefabricated components, while in-situ concrete was used for load-bearing elements such as columns, trusses or "saw-tooth beams". Filigree and hollow prestressed concrete elements were used for the roofs.
In China and Japan, earthquake resistance is a central issue. Local authorities and construction supervisors tend to have a conservative attitude and favour traditional construction methods. Even though the specified requirements could have been met using a substructure or foundations constructed from prefabricated components, it would not have been appropriate to use this method: Strong emotional reasons stood against it.
The grandstands at the Fuji- Speedway in Japan have to withstand an earthquake measuring 8 on the Richter scale without damage, and even during a magnitude 10 earthquake safe evacuation of the venue must be ensured.
On the other hand, the Shanghai circuit was only required to withstand a magnitude 6 earthquake, although for the grandstands the authorities specified a higher value, i.e. up to magnitude 7.
In Bahrain, there are no requirements regarding earthquake resistance. Nevertheless, the location is characterised by extreme ambient conditions: Due to the city state's island location in the Persian Gulf, buildings are exposed to salty sea air on the one hand, yet they also have to resist hot and sandy desert climate. Furthermore, these two climatic conditions regularly lead to wind pressure that can be very strong at times and may develop into sandstorms with associated high sand loads on the roofs and grandstands. This had to be accounted for in the structural calculations as an "equivalent snow load". The designers had to allow for the special climate through increased reinforcement and thicker concrete cover. A minimum cover thickness of 7.5 cm for the foundations and 5 cm for all rising components had to be ensured. Due to their special surface quality, concrete cover for the prefabricated components could be reduced by 1 cm. This was a further strong argument in favour of prefabricated concrete components.
Robert Mehl, Aachen