Beijing University of Technology Gymnasium

　　Highlights
　　Situated in the southeast of Beijing's Chaoyang District and adjacent to East Fourth Ring Road, the Beijing University of Technology Gymnasium hosted the badminton and rhythmic gymnastics events during the 2008 Olympic Games. Covering an area of approximately 66,000 square meters with a total floor space of 24,000 square meters, it has about 7,500 seats and mainly consists of the main competition hall and the warm-up hall. Introduction
　　It may not have the grandeur of the Bird’s Nest or the fluidity of the Water Cube, but anyone who visits or learns about the Badminton Hall can’t help but admire the “lightness” of the gymnasium. The dome has an inner diameter of 93 meters and an outer diameter of 98 meters, with two cantilevered wings on both sides—yet the entire structure uses less than 1,200 tons of steel, equivalent to just 60 kilograms per square meter. In comparison, the Bird’s Nest uses around 400 kilograms of steel per square meter, and the Water Cube about 200 kilograms.　　The dome structure connects five ring cables with steel pipes woven like a fishing net. Within this mesh structure are 102 universal expansion nodes. These so-called universal expansion nodes turn the rigid intersections between the ring cables and the “fishing net” into flexible ones. The flexible joint is created by splitting the fixed node into two halves—the top part has a groove while the bottom is shaped like a hemisphere, similar to a human joint. Working in pairs, they offer better load-bearing performance and greater structural safety.　　In previous dome structures, single radial cables were used to connect the ring cables. But considering that the ring cables are four to five times stronger than the steel pipes, the Beijing University of Technology opted for two tension rods at each connection to form a more stable V-shaped structure, thereby increasing safety and ensuring better material compatibility. This approach is what led architects to describe the gymnasium as “not conquering strength with softness, but blending rigidity with flexibility.”

　　 Chaoyang District, Beijing

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