Beijing National Aquatics Center

Another example of the use of ETFE: Beijing National Aquatics Center (the Water Cube).
 
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https://en.wikipedia.org/wiki/Beijing_National_Aquatics_Center

Beijing National Aquatics Center

Architecture

In July 2003, the Water Cube design was chosen from 10 proposals in an international architectural competition for the aquatic center project.[6] The Water Cube was specially designed and built by a consortium made up of PTW Architects (an Australian architecture firm),[7] Arup international engineering group, CSCEC (China State Construction Engineering Corporation), and CCDI (China Construction Design International) of Shanghai.[8] The Water Cube's design was initiated by a team effort: the Chinese partners felt a square was more symbolic to Chinese culture and its relationship to the Bird's Nest stadium, while the Sydney-based partners came up with the idea of covering the 'cube' with bubbles, symbolising water. Contextually the cube symbolises earth whilst the circle (represented by the stadium) represents heaven. Hence symbolically the water cube references Chinese symbolic architecture.

Comprising a steel space frame, it is the largest ETFE clad structure in the world with over 100,000 m² of ETFE pillows that are only 0.2 mm (1/125 of an inch) in total thickness.[9] The ETFE cladding, supplied and installed by the firm Vector Foiltec, allows more light and heat penetration than traditional glass, resulting in a 30% decrease in energy costs.[9]

The outer wall is based on the Weaire–Phelan structure, a structure devised from the natural pattern of bubbles in soap lather.[10] In the true Weaire-Phelan structure the edge of each cell is curved in order to maintain 109.5 degree angles at each vertex (satisfying Plateau's rules), but of course as a structural support system each beam was required to be straight so as to better resist axial compression. The complex Weaire–Phelan pattern was developed by slicing through bubbles in soap foam, resulting in more irregular, organic patterns than foam bubble structures proposed earlier by the scientist Kelvin.[8] Using the Weaire–Phelan geometry, the Water Cube's exterior cladding is made of 4,000 ETFE bubbles, some as large as 9.14 metres (30.0 ft) across, with seven different sizes for the roof and 15 for the walls.[11]

The structure had a capacity of 17,000[9] during the games that is being reduced to 7,000. It also has a total land surface of 65,000 square meters and will cover a total of 32,000 square metres (7.9 acres).[9] Although called the Water Cube, the aquatic center is really a rectangular box (cuboid) 178 metres (584 ft) square and 31 metres (102 ft) high.[11] The building's popularity has spawned many copycat structures throughout China.[12] For example, there is one-to-one copy of the facade near the ferry terminal in Macau – the Casino Oceanus by Paul Steelman.[13]