Birds Nest

China's National Stadium, or the Bird's Nest, as it has become known, is the world's largest steel structure and the most complex stadium ever constructed. Its design had to be inspiring and be able to withstand an earthquake. So 'light weight' was combined with strength in 110 000 tons of a new grade of steel, the purest ever developed in China, including 36km of steel struts. It is "one of the key engineering marvels in the world today."

China's National Stadium is located on the Olympic Green about 8km from the center of Beijing. As a testament to its significance, it's on the city's north-south axis, which also includes the Forbidden City, Tiananmen Square and the Temple of Heaven, travelling south. It was a demonstration to the world that China is a world class economic power.

The Bird's Nest was the main venue of the 2008 Beijing Olympic Games, when it had a capacity of 91 000 spectators. The stadium now has a capacity of 80 000, as temporary Olympic seating has been removed. It was designed by Swiss Architects, Herzog & de Meuron, and Chinese Architect, Li Xinggang, and is shaped like a cradle, but its interlocking steel members, like a latticework of twigs, make the name Bird's Nest an obvious alias.

The design came from the idea of a single thread wrapped round a ball. Layers of logical geometry give the appearance of randomness and the organic shape of the structure.

The Bird's Nest hosted the opening ceremony, athletic events, the football final and the closing ceremony of the 2008 Beijing Olympic Games, which took place from August 8 to August 24, 2008. It was also the venue for the 2008 Beijing Paralympics athletics and ceremonies from September 6 to September 17, 2008. The stadium will continue to host international and domestic sporting events, such as football matches.

Piles 37m below ground level were required to bear the weight and horizontal forces generated by the structure. Grouting techniques were used to strengthen the ground around the piles, pumping concrete down through the pile cores, making the piles like giant bulbs of reinforced concrete in the ground.

Then the functional inner body of the stadium was put in place. 14700 precast concrete slabs all formed within 2mm tolerance to hold the seating were slotted together. Then followed the 24 anchor points for the columns, 100 tons each. Each column is 1000 tons with no lifting equipment able to lift it.

An international steel shortage meant that the idea for a retractable roof was scrapped, saving 50M USD. A new grade of steel had to be produced to withstand pulling forces within the structure without the addition of extra columns, which would block spectators' views. The purest steel ever developed in China allowed the designers of the Bird's Nest to combine light weight with strength to provide maximum resistance to seismic forces.

Because of Beijing's location, the stadium had be able to withstand an earthquake. Its low sensitivity to welding, however, meant that welders had to be specially trained to join the interlocking steel sections together, with some welds having to be repeated a number of times to achieved specification strength.

The 11200 ton roof was supported by a temporary columns until the moment of truth when the jacks were released and the web of the Bird's Nest held its own weight.

It was a demonstration to the world that China is a world class economic power.

Lots of pentagrams discernable in the interlocking fabric of the structure, like the stars of the Chinese flag.

There is a revealing series of 5 Youtube video clips that cover the construction of this amazing structure.
1    www.youtube.com/watch?v=NqBdlnSxlis&feature=related
2    www.youtube.com/watch?v=Z7va-cLxtEQ&feature=related
3    www.youtube.com/watch?v=Ks8kbZ8ftPw&feature=related
4    www.youtube.com/watch?v=9F9H-gTTKMI&feature=related
5    www.youtube.com/watch?v=NBLb60s9XXg&feature=related

Construction of the National Stadium began on December 24, 2003, and was completed in March, 2008. The total cost was more than 423 million dollars, a tiny fraction of the 40 billion USD spent on Beijing in preparation for the Olympics.
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The Bird's Nest is a colossal saddle-shaped elliptical steel structure with 24 truss-formed supporting columns. It is 333 meters long from north to south, 294 meters wide from east to west, the highest point is 68.5 meters and the lowest point is 42.8 meters. It is the largest world's steel structure. It is covered with a polymer membrane, which is both rain-proof, and translucent (allowing sunlight for the grass). This special membrane enhances lighting within the stadium by diminishing glare and shadowing, giving a more favorable competition environment.

One Day Beijing Olympic Stadium Tour from $78 p/p (based on travel party of 2-3 persons)