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

本研究以框架体系的原理为中心，旨在了解近代以前日本木结构建筑屋顶框架的发展。首先，从建筑要素的角度对目前的分类进行了批判，并参考了国外范例的类型，对屋顶框架的类型学进行了概述，包括国内范例中不适用的类型学。我们重新考虑了各种建筑类型所采用的屋顶框架。基于上述，本研究将讨论限制在农舍，农舍在中世纪和前现代时期的屋顶框架类型中表现出最广泛的多样性。首先，仔细检查框架成员，从主要的三个支撑系统中提取支撑类型：脊和柱框架，檩条和柱框架，以及sasu框架（类似于主椽）。将屋顶框架类型应用于663所房屋，全面揭示了各地和全国各地的不同方面。其次，分析屋跨与框架类型的关系，屋跨越大，需要的支撑构件越多，但对于sasu框架，是否设置中心柱并不是因为屋跨的大小。最后，对柱框架（包括梁与柱框架、檩条与柱框架）与sasu框架的过渡形式进行了比较，得到了以下结果：位于日本东部地区的桥，没有经过原来的脊柱架形式，即柱直接支撑脊块的过程，从檩条架向sasu架转变；而位于日本西部的地区则在脊柱架和沙苏架的共同作用下逐渐转变。

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.