China built the Forbidden City to withstand earthquakes - without using a single nail
- It sounds a near impossible task: build an earthquake-resistant wooden building without using nails or glue
- The dougong system allowed buildings to sit lightly on the floor without needing to be sunk into the ground
Even today, it sounds like a near impossible task: build an earthquake-resistant wooden building, strong enough to endure several tumultuous centuries, without using nails or glue.
Chinese carpenters rose to the challenge more than 600 years ago.
Elevating a simple principle
One of the most instantly recognisable aspects of Chinese architecture is temple roof design. The visually compelling and highly complex structures that support roofs use wooden joints set into columns and pillars. More than a beautiful signature, the deceptively simple technique is durable and quick to assemble.
What is the secret behind the strong but flexible structure? Bracket sets are created by placing a wooden block (“dou”) onto a column to form a solid base. Another wooden bracket (“gong”) is then inserted into the dou to support either a wooden beam, or another gong.
As multiple dougong brackets are added, the joints are compressed weight is distributed evenly throughout the structure. This way, individual elements are not prone to splitting or cracking and the system of interlocking beams cannot be shaken apart, or shattered under stress.
Adding new layers of brackets on top means the dougong pieces need to be slightly modified. There are about 30 combinations with simple variations to create different structures, but the core principle remains identical throughout. The system creates an incredibly robust structure which sits lightly on the floor without needing to be sunk into the ground
During the Ming dynasty, variations on the basic shapes of the dougong system were developed, allowing for taller and more decorative structures. It is believed that the more layers of brackets, the superior the building.
The corner towers
Observation points were strategically built at each corner of the Forbidden City. They are among the most intricate structures in the city complex because this was considered befitting of their crucial function.
The Palace Museum tour guides enjoy regaling visitors with a tale on the origin of the corner towers. It begins with the emperor giving his head eunuch just three months to create a stunning design for the towers or face execution.
As days go by, the eunuch deems each of his designs not good enough for the emperor. On the final day before the deadline, he throws his hands up in despair. Realising he is going to die the next day, he decides to spend his final night on Earth doing what he loves most: making a cage for his pet cricket. The following morning, the emperor sees the cage and is completely besotted with the design.
The happy ending sees the architect’s life spared and the corner towers built in the design of the cricket cage.
