In addition, the hoisting of the main truss in the inner ring of the roof and the installation of the substructure of the facade have been fully launched. The thickness of steel used in the "Bird's Nest" steel structure can reach 1 1 cm, which has never been produced in China. In addition, a translucent film will be pasted on the outer surface of the grid structure at the top of the "Bird's Nest".
After using this film, the light in the stadium is not direct, but diffuse, making the light softer. Diffused light can also solve the maintenance problem of the stadium lawn, and also has the function of shielding the seat from wind and rain.
Features:
The external structure of the "Bird's Nest" is mainly composed of a huge portal steel frame and 24 truss columns. The design service life of the main structure is 100 years, the fire resistance rating is Grade I, the seismic fortification intensity is Grade 8, and the waterproof rating of underground engineering is 1.
The main building of the project is a space saddle-shaped oval with a length of 333 meters from north to south. The huge space saddle-shaped steel truss weaves a "bird's nest" structure. The total steel consumption of the steel structure is 42,000 tons, and the concrete stands are divided into upper, middle and lower floors. The concrete structure of the stand is a reinforced concrete frame-shear wall structure system, with 7 floors underground 1 floor and above ground.
The steel structure and the upper part of the concrete stand are completely separated, and they are not connected with each other, but are enclosed in form, and the foundation sits on the connected foundation plate. The roof steel structure of the National Stadium adopts a double-layer membrane structure, that is, a transparent upper ETFE membrane fixed between the upper chords of the steel structure and a translucent lower PTFE sound-absorbing ceiling fixed under the lower chords of the steel structure and the inner ring side wall.