紫禁城古建筑的传统防震方法

TRADITIONAL ASEISMIC METHODS OF ANCIENT BUILDINGS IN THE FORBIDDEN CITY

位于北京市中心的紫禁城(故宫博物院前身)拥有世界上规模最大、保存最完整的木结构古建筑群。在历史上遭遇数百次地震但仍然保持完好,体现了其良好的抗震构造。研究表明,紫禁城古建筑基础为分层叠加的灰土基础,且掺入有利于抗震的黏性材料;柱底平摆浮搁在柱顶石上,可产生滑移隔震效果;梁与柱采取榫卯节点形式连接,可产生摩擦耗能效果;斗拱分层叠加,可耗散部分地震能量;梁架低矮,既可避免大尺寸梁截面的使用,也可避免其在地震作用下产生倾覆。

The Forbidden City (the Palace Museum predecessor) is located in the center of Beijing,which owns the largest scale as well as number of ancient timber buildings in the world. The buildings survived several hundred of earthquakes in history,reflecting good aseismic performances. The research results showed that the bases of the buildings were made by layers of lime-soil,which was fixed by viscous material;the bottom of each column foot was free-standing on stone base for seismic isolation;beam and column were connected by tenon-mortise joint,which could consume part of earthquake energy;the bracket sets (tou-kung) were composed of layers of small timber blocks,which could also produce shock absorption by relative motion among the blocks. Besides,the low height beam system could avoid not only using large section size of timber,but also the overturn of the structure.