故宫古建筑斗拱典型残损问题分析

Typical structural problems of bracket sets in the Forbidden City

为保护古建筑,采取现场勘查与分析论证相结合的方法,以故宫古建筑斗拱为研究对象,研究了木构古建筑斗拱的典型残损问题与加固方法。基于故宫斗拱构造和受力特点,对其典型残损问题进行了归纳和汇总,分析了问题产生的原因,提出了加固建议。结果表明:故宫古建筑斗拱出现的典型残损问题包括糟朽、变形、开裂、松动、脱落、原有加固件失效等;产生这些残损问题的原因与古建大木施工工艺、木材及加固件材性、斗拱构造特征、外力作用等因素密切相关;采取重新安装、局部更换、胶粘、化学加固、铁件加固等方法均可实现斗拱的有效加固。

To protect ancient buildings, bracket sets （tou-kung） in the Forbidden City were taken as an example to study their structural problems and strengthening methods by survey as well as analysis methods. According to constitution characters and bearing performances of these bracket sets, their typical structural problems were summed up, causes for the problems were discussed, and strengthening advices were proposed. Results show that typical structural problems of these bracket sets include decay, crack, deflection, slack, disengage of parts and invalidation of strengthening iron members and so on ; main causes for these problems relate not only to constitution, construction process as well as bearing performances of bracket sets, but also material properties of wood and strengthening members; besides, effectively strengthening methods for these bracket sets include reassembling, local replacement, glue, chemical means, iron components connection and so on.