How did the 6,750 tons of Steel Frame Building of the National Center for the Performing Arts achieve not a single pillar

The National Center for the Performing Arts has indeed reflected the international first-class level in architecture, pioneered domestic architecture, and made many bold attempts, such as the use of titanium metal plates, which are mainly used in the manufacture of aircraft and other aircraft, as building roofing materials. The bold oval appearance and the surrounding water surface constitute an architectural shape of a pearl on the water, novel, avant-garde, and unique. As a whole, it embodies the characteristics of the world landmark buildings in the 21st century, and can be called the perfect combination of traditional and modern, romantic and realistic.

The design of the National Center for the Performing Arts began with two principles: first, it is a world-class theater; Second, it cannot rob the Great Hall of the People. The final Grand theater presented in front of the world with a huge oval, becoming a landmark building with novel shape and unique concept.

According to the vision of the famous French architect Paul Andreu, the landscape after the completion of the National Theatre is as follows: in a huge green park, a pool of blue water surrounds the oval silver theatre, and the titanium sheet and glass shell reflects the light of day and night, and the color changes. The theater is surrounded by partially transparent gold mesh glass walls and topped with a view of the sky from inside the building. Some people describe the appearance of the Grand theatre after its completion as "a drop of crystal water".

1. China's largest dome is built from 6,750 tons of steel beams

The NCPA shell consists of curved steel beams, a huge steel dome that can almost cover the entire Beijing Workers' Stadium.

Surprisingly, such a large steel frame structure is not supported by a single pillar in the middle. In other words, the steel structure weighing 6750 tons must completely rely on its own mechanical structure system to ensure safety and stability.

This flexible design makes the National Center for the Performing Arts like a tai chi master who defuses all kinds of forces from the outside world with soft and rigid means. In the design of the steel structure of the Grand theater, the amount of steel used in the entire steel structure is only 197 kilograms per square meter, which is lower than many similar steel structure buildings. The construction of this shell steel structure is extremely difficult, and the crane with the largest tonnage in China is used when hoisting steel beams.

2. Pour underground water barrier wall to prevent surrounding foundation settlement

The National Center for the Performing Arts is 46 meters high, but its underground depth is as high as a 10-story building, 60% of the construction area is underground, and the deepest is 32.5 meters, which is the deepest underground project of public buildings in Beijing.

There are abundant underground groundwater, and the buoyancy generated by these groundwater can lift a giant aircraft carrier weighing 1 million tons, so huge buoyancy is enough to lift the entire National Grand Theater.

The traditional solution is to pump groundwater continuously, but the result of this pumping of groundwater will be the formation of a 5km underground "groundwater funnel" around the Grand Theater, causing the surrounding foundation to settle and even the surface of the building may crack.

In order to solve this problem, engineers and technicians have conducted precise research and poured an underground water barrier with concrete from the highest groundwater level to the clay layer 60 meters underground. This huge "bucket", formed by an underground concrete wall, encloses the foundation of the Grand Theatre. The pump pulls the water away from the bucket, so that no matter how much water is pumped from the foundation, the groundwater outside the bucket is not affected, and the surrounding buildings are safe.

3. Air conditioning in confined Spaces

The National Center for the Performing Arts is a closed building with no external Windows. In such a closed space, the indoor air is completely regulated by the central air conditioner, so certain requirements are put forward for the health function of the air conditioner. After SARS, the engineering staff of the Grand Theater raised the standards of air conditioning installation, return air system, fresh air unit, etc., to further improve the standards to ensure that the central air conditioning meets the health standards.

4. Installation of titanium alloy roof

The roof of the Grand Theatre has 36,000 square meters and is mainly made of titanium and glass panels. Titanium metal has high strength, corrosion resistance and good color, and is mainly used in the manufacture of aircraft and other aircraft metal material. The roof will be assembled from more than 10,000 titanium plates about 2 square meters in size. Because the installation Angle is always changing, each titanium plate is a hyperboloid, with different area, size and curvature. The thickness of the titanium metal plate is only 0.44 mm, which is light and thin, like a thin piece of paper, so there must be a liner made of composite material below, and each liner will be cut to the same size as the titanium metal plate above, so the workload and work difficulty are extremely great.

At present, there is no such a large area of titanium metal plate in the international building roof. Japanese buildings use titanium plates more, this time the Grand Theater will commission a Japanese manufacturer to produce titanium metal plates.

5. Cleaning of roof shell top

The cleaning of the titanium roof shell is a troublesome problem, and it is proposed that if the manual cleaning method is used, it will appear awkward and unbeautiful, and advanced technology should be used to solve it.

At present, engineers are inclined to choose a high-tech nano coating, which will not stick to the surface of the object after coating, as long as the water is flushed, all dirt will be washed away.

However, because this is a new technology, there is no similar engineering example to refer to, engineers are carrying out laboratory strengthening tests on this nano coating, whether to use the test results can be determined after.

6. All domestic stone, showing a beautiful earth

The Grand Theater used more than 20 kinds of natural stone, all from more than 10 provinces and cities in China. The 22 areas of the hall alone use more than 10 kinds of stone, named "Splendid earth", meaning the splendid mountains and rivers of the Chinese nation.

There are "Blue diamond" from Chengde, "Night rose" from Shanxi, "Starry Sky" from Hubei, "sea shell flower" from Guizhou... Many of them are rare varieties, such as the "green golden flower" from Henan, which is out of print.

The "white jade jade" laid in the olive Hall produced in Beijing is a white stone with diagonal green ribs, diagonal lines are naturally generated, and all in the same direction, which is very rare. The total stone laying area of the grand theater is about 100,000 square meters, the engineering personnel insist on the use of domestic stone, after several twists and turns to find all the stone that matches the designer's concept in color and texture.

Such a large scale non-radiation stone mining, processing is also a huge challenge for engineering personnel, even the designer Andrew also marveled at the colorful colorful Chinese stone and Chinese stone mining, processing technology exquisite.

7. Get out quickly and safely

The three theaters of the National Grand Theater can accommodate a total of about 5,500 people, plus the cast and crew up to 7,000 people, due to the unique design of the National Grand Theater, the theater is surrounded by a giant open-air pool, so in the event of an emergency such as fire, how to quickly 7,000 audience from the water surrounded by the "eggshell" in the safe evacuation, at the beginning of the design, It's a tricky problem for designers to solve.

In fact, the fire escape tunnel at the National Center for the Performing Arts was ultimately designed to allow 15,000 people to evacuate quickly. Among them, there are eight to nine evacuation paths, each three and seven meters underground, which pass under the giant pool and lead to the outer plaza. Through these passageways, spectators can be safely evacuated within four minutes, which is less than the six minutes required by the fire code.

In addition, there is a ring fire channel up to 8 meters wide designed between the theater and the open-air pool, which is quite spacious and can accommodate two fire trucks passing side by side, while also leaving a two-meter wide pedestrian channel, firefighters can reach the fire point in time through the fire channel, so that the fire personnel and evacuated personnel can go their own way without interfering.

This "theater in the city, the city in the theater" appears with a strange attitude of a "pearl in the lake" beyond imagination. It expresses the inner vitality, the inner vitality under the outer tranquility. The Grand Theatre represents the end of one era and the beginning of another.