Does a decorative design in architecture connote the engineering purpose?

In ancient Greek architecture, entasis, a convex curve, is well discussed that it is not only intended for the aesthetic purpose with which people can perceive visual stability but also for the engineering purpose of enhancing strength. There is, however, not investigated well in Japanese medieval wooden buildings.

Thus, the purpose of this study was to investigate engineering purpose of a decorative design on a Japanese medieval building and discuss the integration of engineering mind and aesthetic mind of the carpenter.We focused on a design of Kaerumata in the 13th century which is a strut of a building and supports a load. In medieval Japan, it was a transition period in which Kaerumata has changed its role from a structural element into a decorative one.

A design of Kaerumata is one of the indicators of dating buildings because it varies depending on the age and area. Since the design of Kaerumata differs depending on the carpenter, it is suitable for indirectly exploring his sense of visual dynamics which can intuitively estimate mechanical properties of objects by elucidating the mechanical rationality in the design.

We performed structural analysis using finite element method and the results showed that the two holes of Kaerumata’s decoration lead to structural rationality which implies it positively affects internal stress. We discussed carpenters in the 13th century could unintentionally design that two small holes as a structural role and had a great sense of visual dynamics.