BIRD's Nest - A TECHNICAL VIEW

1.The main body of the National Stadium has a design life of 100 years. Its fire resistance capability is first-rate, and it can withstand an eight-magnitude earthquake. The water-resistance capability of its underground project is also first-rate.

2.The main body of the National Stadium is a colossal saddle-shaped elliptic steel structure weighing 42,000 tons. It is 333 meters long from north to south, 294 meters wide from east to west, and 69 meters tall.

3.To earthquake-proof the stadium, the bowl and roof were split into two separate elements and the bowl split into eight zones, each with its own stability system and effectively its own building.

4.The ground was broken on Christmas Eve December 2003, and construction started in March 2004. Construction was halted following the collapse of Terminal 2E at Paris Charles de Gaulle International Airport, which had a similar design to the National Stadium.

5.The stadium can seat as many as 91,000 spectators during the Olympics. The capacity will then be reduced to 80,000 after the Games.

6.The stadium is 330 metres (1,082 ft) long by 220 metres (721 ft) wide, and is 69.2 metres (227 ft) tall. The stadium uses 258,000 square metres (2,777,112 square feet) of space and has a usable area of 204,000 square metres (2,195,856 square feet). It was built with 36 km of unwrapped steel, with a combined weight of 45,000 tonnes.

7.The stadium will cost up to 3.5 billion yuan (423 million USD).

8.The large steel skeleton of the project weighs 42,000 tons, with the roof and the hanging parts around it accounting for 11,200 tons.

9.According to the plan, the outer circle will vertically drop by 67-70mm, the middle by 161-178mm and the inner by 208-286mm.

10.The skeleton can now bear a load of 11,200 tones of its roof and hanging parts.

11.Computer simulation, synchronized control and structure monitoring techniques were all used to ensure accurate operation, even unloading and timely observation.

12.In 2002, Government officials engaged architects worldwide in a design competition. Pritzker Prize-winning architects Herzog & de Meuron collaborated with ArupSport and China Architecture Design & Research Group to win the competition.

13.The opening and closing ceremony of the Beijing olympics will take place in the bird’s nest.

14.The Beijing National Stadium’also known as the National Stadium, or the “Bird’s Nest” for its architecture is a stadium finished for the Olympic Green in Beijing, China that was completed in March 2008.

15.The stadium will host the main track and field competitions for the 2008 Summer Olympics, as well as the opening and closing ceremonies. It is located east of the Beijing National Aquatics Centre.

The National Stadium is a complex structure, posing great difficulties for its designers and constructors.

1. Large and heavy steel parts

The fracture surface of the largest truss column — the major load-bearing component of the roof structure — measures 25m x 20m, with a height of 67m. The maximum weight of a single column is 500 tons. The main truss is 12m tall. The maximum span between and through the two columns amounts to 145.577+112.788m, and the maximum span between the two trusses stands at 102.39m. Each truss column is of great bulk and weight, and so are the main trusses.

2. Complex nodal joints

Because the structural elements in the project are box-typed, many elements intersect spatially among the steel parts. Besides, the complex nature of secondary structures has resulted in the diversity of nodal joints of the main structures, requiring accurate and sophisticated manufacturing and installation.

3. Tight schedule

In addition to the huge workload, the allotted construction period is short. Having started on December 24, 2003, the project is expected to be completed by the end of 2007, with the inauguration time scheduled for March 2008. Therefore many operations have to be conducted on a limited terrain, causing a very tense situation.

4. The hoisting work extended across the winter and spring, so the workers have had to defy both rainy and cold conditions in the winter to continue their work.

The workers have overcome tremendous engineering and technical challenges in the process of construction:

1. Difficult work arrangement

They need to do very detailed research of operations and follow meticulous arrangements to complete various kinds of work within a limited workspace.

2. Difficult hoisting of steel parts

To facilitate the assembly of the steel parts, the workers have to use a prone position to assemble the truss columns, which requires a turnover process before they are hoisted. The choice of the hoist points and lug hooks pose great difficulties in the face of bulky and cumbersome steel parts, and the change of pulling stress from three directions must be taken into consideration. The workers need to meticulously rectify angles and positions of the box-typed sectional parts to ensure accurate abutment during the hoisting process.

3. Difficult stabilizing process

They also have to fight the heavy wind load and keep the stability of the steel parts by following a strict working order and use lateral stability measures including the use of anchoring method and wind-holding ropes.

4. Difficult welding

The welders not only face a huge work volume, but also have to work on both the thin steel sheets and thick steel slabs, on high-strength and cast steel elements, and take downward, vertical or overhead positions while welding. They face temperature changes, steel deformation and intensive labor. They need to work above ground, in winter rain and under windy conditions.

5. Difficult installation

The workers face difficulties in ensuring accurate installation as the steel parts and the related gigs and fixtures can be deformed easily under their own dead weight and the change of temperatures. The workers must take pre-installation measures to rectify and relieve the errors that might occur in the process of installation.

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