Seismic principles of Ancient Chinese buildings

    Many buildings in ancient China have experienced many strong earthquakes, which is an earthquake miracle in The history of China and even the world. Flexible frame, table isolation, brackets support and tenon connection are the seismic mechanism of ancient wood structure.
    The wooden structure of ancient residential buildings is divided into foundation, column frame layer, pavement layer and roof from bottom to top. The wooden frame bears most of the load of the structure, while the wall only plays a role of partition and closure.

1. Seismic effect of ancient building materials
    Wood is a flexible material with tensile, flexural and elastic resistance. Wood can absorb and consume earthquake energy well in the earthquake process, and has a strong ability to recover deformation. It can produce large transverse deformation without fracture damage under horizontal earthquake.

2. Seismic prevention effect of ancient building structure
    (1) The appearance of wooden buildings usually adopts an aspect ratio of less than 2:1 or approximately square, which makes the mass and horizontal stiffness of the building more uniform with the change of height. The regular symmetrical layout maximizes the overlap between the center of mass and the stiffness center of the building, which greatly avoids the torsion effect of shear effect on the wall when the building is hit by an earthquake.

  （2） The wooden frame bears and transmits the entire load of the roof, while the walls only keep the space isolated. Under the action of earthquake, friction sliding at the joint and rotating sliding at the bottom of the column form a good isolation energy dissipation structure system.

    (3) In wooden structure buildings, structural components adopt mortise and tenon connections. Although the load-bearing area of wooden components is weakened and the load-bearing capacity of nodes is reduced, the material in the ancient structure is large enough to weaken the wood section area to withstand greater loads, so as to make full use of the flexibility of semi-rigid joints. Mortise and mortise joints not only change the characteristics of the structure, but also dissipate the seismic energy due to the friction of the mortise contact surface, which is equivalent to installing a damper on the node, thus reducing the seismic response of the structure.

3. The seismic effect of ancient buildings on the whole
    On buildings, some have many columns. When the seismic force is applied to the building, the columns create a buffer between them, so that the building will not be damaged by the sudden earthquake.
    Some buildings use a multi-storey frame, similar to the ring beams of modern buildings, which is a very effective method of seismic T-section reinforcement.
When the seismic force is applied to a building, for multiple triangles, some of the seismic force between the bracket and beam will be dispersed to several small triangles, so that the seismic force is not concentrated at a certain point.