Tou-Kung as a unique invention of Chinese ancient architecture, it has several advantages for wooden construction:

• Increase outgoing eaves:   The large overhangs merely for artistic effect but functional, keeping out the rain and sunlight, for wooden structural frame, it's necessary to prevent damage from moisture and insulation. it's really a problem before Tang Dynasty.
• Eliminate the danger of  breaking beam:   Before invention of Tou-kung that locate between roof and column, the weight of roof focused on the beam directly. But later, since the invention of Tou-Kong, the weight of roof could be transited by Tou-Kung layer by layer. It avoid to put a large pressure on beams suddenly, which is really easy to destroy the beam if the weight is too large.
• Aseismatic function:  Since Tou-Kung are clinker-built, all of its member fit together overlap but not fixed, energy of  shake could be absorbed and reduced when it's transiting through structures. it's a good way to reduce the damage of earthquake.
• The sign of ascendancy:   In the feudal society, the use of Tou-Kung had strict regulation, only gerentocratic residence or temple could use it. And overhanging of Tou-Kung also had been used to identify the grade of building, normally for one building,  more the layer's number of  Tou-Kung, more high is its grade.On the other hand,the width of Tou-Kou is also another identified way. In Song Dynasty, the regulation of material of Tou-Kung was divided into 8 classed, but in  Qing Dynasty, Tou-kou has 11 classes for the grade of architecture.

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