An evolutionary study of traditional timber framed building in Japan focusing on the principle of framing systems of the roof construction

本研究旨在了解近代以前日本木结构建筑屋顶构架的发展，以构架体系的原理为中心，首先从建筑构件的角度对现行的分类进行批判，并参考国外实例的类型，对屋顶构架的类型学进行了概括，包括国内不适用的实例。并重新考虑了各种建筑类型所采用的屋顶框架。基于上述原因，本研究将讨论范围限定在中世纪和前现代时期屋顶框架类型多样性最大的农舍。首先，仔细检查框架构件，从三种主要支撑系统中提取支撑类型：脊柱框架、桁柱框架和Sasu框架（类似于主椽）。通过对663套房屋的屋盖结构型式的分析，揭示了我国各地屋盖结构的特点。其次，分析了屋盖跨度与结构型式之间的关系，指出屋盖跨度越大，需要的支撑构件越多，而在砂砂结构中，是否设置中柱与屋盖跨度无关。最后，通过对屋盖结构型式的分析，得出了屋盖跨度与结构型式之间的关系。通过对柱框架（包括屋脊柱框架和檩条柱框架）与sasu框架的过渡形式进行比较，得出以下结论：位于东日本的则倾向于由桁柱框架向佐助框架的转化，而没有经过脊柱框架的原始形态过程，即柱直接支撑脊片;而位于西日本的则倾向于在脊柱框架和佐助框架的共同影响下逐渐转化。

This study aims to comprehend the development of roof frame of timber framed building in Japan before modern period focusing on the principle of framing systems.As the beginning, criticizing the current classification from the standpoint of the building elements, and referring to the types of foreign examples, we took a general view of typology of the roof frame including those which was not apply domestic examples. And we reconsidered the roof frame adopted by various building type. Based on the above, this study limited the discussion to farmhouses which show the widest diversity in the type of roof frames in the medieval and premodern period.First, examining closely the framing members, supporting types were extracted from major three supporting systems : ridge and post frame, purlins and posts frame, and sasu frame (similar to the principal rafter). Applying the types of roof frame to 663 houses, distinct aspects of localities were revealed exhaustively and across the nation.Secondly, analyzing the relation between the roof span and the type of frame, there is the tendency that the longer roof span needs more supporting members, however in the case of sasu frame, it's not due to the roof span whether the center post is erected or not.Finally, comparing the transitional forms between post frame (including ridge and post frame and purlins and posts frame) and sasu frame, the following results were obtained. Those which located in the east Japan tended to transform from purlins and posts frame to sasu frame without the process of the original form of ridge and post frame which means the post directly support the ridge piece ; while those which located in the west Japan tended to transform gradually influenced by both ridge and post frame and sasu frame.