Creep of the beam in Japanese conventional structures composed of green and kiln-dried timber, 1: Differences in relative deflections of the beams

• Published in: Journal of the Faculty of Agriculture - Shinshu University (Japan) Vol. 42; no. 1-2
• Main Authors: Takeda, T.(Shinshu Univ., Minamiminowa, Nagano (Japan). Faculty of Agriculture), Arima, T
• Format: Journal Article
• Language: English
• Published: 01.03.2006
• Subjects: BOIS DE CHARPENTE; CHAMAECYPARIS OBTUSA; HUMEDAD RELATIVA; HUMIDITE RELATIVE; MADERA DE CONSTRUCCION; MERMA; PSEUDOTSUGA MENZIESII; RELATIVE HUMIDITY; RETRAIT; SHRINKAGE; STRUCTURAL TIMBER; TEMPERATURA; TEMPERATURE
• ISSN: 0583-0621

The main purpose of this research was to evaluate the bending creep of beams in Japanese conventional structures (posts and beam constructions), known in Japanese as "jiku gumi." We built two wooden structures in order to carry out creep tests: one was composed of green timber (G) and the other of kiln-dried timber (D). Each structure was composed of four sills, four posts, two girders, and two beams. The tenon and mortise at specific locations in the members were processed with a molding machine at a sawmill. Long-term design loads were applied at the top of each beam. The deflections at mid-span were measured for each beam. Results showed that the ratios of total deflection to initial defection (relative deflection) over a 878-day period were 3.75 and 2.26 for the G and D structures, respectively. After unloading, the ratios became 3.04 and 1.50 for G and D, respectively. The additional relative creep deflection (=relative deflection-1) observed in G were approximately two times that found in D.