故宫古建檩三件典型残损问题分析

Typical Structural Health Problems of Purlin Components of Ancient Buildings in the Forbidden City

基于檩三件典型构造和受力特点,对其典型残损问题进行了归纳和汇总,分析了问题产生原因,提出了加固建议。结果表明:故宫古建筑檩三件容易出现的残损问题包括糟朽、挠度、开裂、构件分离、垫板歪闪、连接松动等,产生这些残损问题的原因与古建大木施工工艺、木材材性、檩三件构造特征、外力作用等因素密切相关;采取铁件或CFRP材料包裹、贴补,以及拉接、支顶、化学加固、替换等方法均可实现檩三件的有效加固。

According to constitution characters and bearing performances of these purlin components,their typical structural health problems were summarized,causes for the problems are discussed,and strengthening advices based on analysis examples are proposed. Finally,engineering example of CFRP strengthened purlin components of Zhonghe Palace are further discussed,which verifies the strengthening methods. Results show that typical structural health problems of these purlin components include rot,crack,vertical deflection,disengage of parts,lateral deflection of middle board,slack of connection between purlin ends and so on; main causes for these problems relate not only to constitution,construction process as well as bearing performances of purlin components,but also material properties of wood; besides effectively strengthening methods for these purlin components include iron connection,additional support,wrap by iron or CFRP,piece up by iron or CFRP,chemical reinforcement,replacement and so on.