Join(t)ing the Past and Present: A Dive into the History, Construction, and Structural Properties of the Traditional Japanese Daimochi Tsugi Timber Joint

Abstract

Heritage structures serve as a record of the past and symbolize enduring connections between a community's culture and history. While historical Japanese timber joints built by miyadaiku carpenters and utilized in temples and shrines are recognized as sustainable and resilient building systems, the preservation of such structures and carpentry knowledge face challenges due to the aging population, decreasing carpenter population, and knowledge gaps. For the daimochi tsugi timber joint specifically, while information exists on its geometry, little is known about its history, design, or structural behavior. Thus, there is a need to better understand traditional Japanese woodworking techniques and joints for heritage preservation and potential modern applications. To address this lack thereof, this thesis explores the context, construction process by hand and CNC, and structural performance of the daimochi tsugi. It was found that for a similar amount of effort, hand construction provided a more precise joint, a linear elastic model was able to accurately predict areas of cracking, and the joint performed the best with a larger clamping force, per its historical use. The results contribute to an ongoing effort to gain a better understanding of and explore ways to facilitate the more efficient construction and use of Japanese joints.