The presence of earthquakes in China has resulted in timber-framing practices that put European design to shame. As early as 500BC, builders in China developed disaster-resistant structures with interlocking flower-shaped brackets called dougong that reduce the impact of earthquakes on buildings. These joints are so effective, they have helped the Forbidden City in Beijing withstand 200 earthquakes in 600 years.
Specialist carpenters decided to find out how the Forbidden City has survived so many earthquakes, including the 20th century’s deadliest quake. They constructed a scale model of a structure atop a shake table. To strive for accuracy, they drew on traditional techniques and tools. They then put the structure, a fifth of the size of buildings in the Forbidden City, through simulated earthquakes. The largest earthquake we’ve ever recorded in history had a 9.5 magnitude. But the scale model withstood not only that but a 10.1 magnitude simulated earthquake – and in a video showing the quake, didn’t fall down.
This will rock your world.
Posted by Channel 4 on Thursday, July 20, 2017
Dougong are often found nestled beneath the eaves and roof, and in case of a quake, they transfer roof weight to the supporting columns found on these old buildings. They don’t need nails or glue to hold together. The brackets don’t shake apart easily, but also aren’t so stiff they’ll shatter under pressure. Multiple joints help them remain stable.
One of the more mind-boggling aspects of the test was that the columns of the building designed like those in the Forbidden City were freestanding, and weren’t sunken into foundations. They wobbled in a 10.1 magnitude simulated earthquake, but didn’t collapse in the video.
Dougong can be glimpsed on palaces and temples, for example, and according to People’s Daily Online was utilized widely during the Spring and Autumn Period in Chinese history, which spans from around 770 to 476 BC.