Structural Performance Evaluation of Column-Nuki Connection in Traditional Japanese Wooden Buildings

Abstract

Traditional Japanese wooden buildings have been constructed using internal wooden frame structures. Plus-shaped column-nuki connections are important to evaluate the seismic performance of these buildings, and these connections include several joint types, one of which is the oblique scarf joint. However, only very few extant studies have examined column-nuki connections and oblique scarf joints. Consequently, no design equations exist for this combination. Therefore, it is possible that the structural performance of column-nuki connections might be inaccurately evaluated. Thus, this study aims to evaluate the structural performance evaluation of column-nuki connections in traditional Japanese wooden buildings. Full-scale tests were performed on specimens with either the continuous or oblique scarf joint nuki, and results obtained were compared based on parameters, such as the type of connection and number of dimensions. Subsequently, corresponding analytical results were calculated using an extant design equation, and the same were compared against experimental values to determine the validity of using the design equation for column-nuki connections in traditional Japanese wooden buildings. Results obtained in this study demonstrate the initial stiffness to be approximately identical for specimens with continuous or oblique scarf joint nuki. The yield and ultimate bending moment of oblique scarf joint nuki specimens were observed to be approximately 10–70% smaller compared to those corresponding to continuous nuki specimens. In addition, all oblique scarf joint nuki specimens demonstrated an initial cleavage failure followed by multiple failures. Results of these comparisons demonstrate that failure can be partially estimated using the extant design equation considered in this study.

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References

[1] Kaori Fujita, Isao Sakamoto, Yoshimitsu Ohashi: A Study on lateral loading test of column and batten (nuki) joint used in traditional wooden architecture (Part 1), Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, Structures-Ⅲ, pp.103-104, 1996.09 (in Japanese)

[2] Editorial Committee for Manual of Seismic Design for Wooden Frame Structures: Manual of Seismic Design for Wooden Structures Taking Advantage of Traditional Structural Techniques - Methods for Seismic Design and Seismic Reinforcement Design Based on Response-Limit Capacity Analysis -, Gakugei Shuppan Sha Co. Ltd., Japan, March 2004, pp.79

[3] Architectural Institute of Japan (edited): Design Manual for Engineered Timber Joints, Maruzen, Japan, September 2010, pp. 254-257.

[4] Japan Housing and Wood Technology Center: Project Report about points to consider for design of timber structures (in Japanese), March 2018, pp. 216-226.

[5] Architectural Institute of Japan (edited): Standard for Structural Design of Timber Structures, Maruzen, Japan, March 2009, pp. 36-37.