What system does Sears Tower in Chicago, USA belong to?

Belonging to a beam tube structure system.

The Sears Tower (English: Willis Tower), also translated as Willis Group Building, is a skyscraper located in Chicago, Illinois, USA. It used to be the tallest building in North America, and 1 October 2nd 20 10 was broken by World Trade Center1building. When it was completed, it was named Sears Tower. In 2009, Weilai Group, an insurance brokerage company headquartered in London, agreed to rent a large part of the building as an office building and obtained the naming right of the building as part of the contract. On July 6, 2009 10: 00, the building was officially renamed as Weilai Group Building. Sears Tower has 1 10 floors and was once the tallest office building in the world. About 65438+6500 people come to work here every day. There is an observation deck on the 103 floor for tourists to overlook the whole city. It is 442 meters above the ground, and you can see four states in the United States when the weather is clear. The structural engineer of this building is F. Kahn, 1929, an American architect born in Dhaka. The design wind pressure at the top is 305 kgf/m2, the design allowable displacement (allowable amplitude during vibration) is 1/500 of the total height of the building, that is, 900 mm, and the measured displacement is 460 mm under the maximum wind speed after completion. In order to solve the key wind-resistant structural problems of high-rise buildings like Sears Tower, he put forward the concept of beam-tube structure system and put it into practice. The whole building is regarded as a cantilever beam tube space structure. The farther away from the ground, the smaller the shear force is, and the vibration caused by wind pressure on the top of the building is obviously reduced. The design wind pressure at the top is 305 kgf/m2. All towers have the same width, but different heights. The black belt outside the building cleverly covers the service facilities area. The building adopts a bundle tube structure system composed of steel frames, and the exterior adopts black aluminum and coated glass curtain walls.