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Creep of the beam in Japanese conventional structures composed of green and kiln-dried timber II: predictive model for relative deflections

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Abstract

We conducted creep tests to evaluate creep behaviors of conventional Japanese framing (jikugumi) structures as reported in a previous article. We measured beam deflections of two structures: one of them was composed of only green timbers (G) and the other with only kiln-dried timbers (D). Besides the two structures, we prepared green and kiln-dried beams to measure moisture content (MC), weight, and dynamic Young’s modulus (E f) by the longitudinal vibration method. We attempted to predict deflections of beams in the structures by using experimental data for single beam specimens. The proposed simple predictive model was derived from two equations: a relation between MC and equilibrium moisture content calculated with temperature and relative humidity, and a relation between MC change and relative deflection change. Beam deflections were traced for 2.5 years, while the predictions were based on experimental data from loading to the 11th day of the test. It was assumed that sensitivity of deflection change to MC should differ during desorption or adsorption. Although annual cyclic changes were observed in E f, there was no obvious relationship between E f and beam deflection.

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Author information

Correspondence to Takashi Takeda.

Additional information

Part of this article was presented at the Annual Meeting of the Architectural Institute of Japan, Kyushu, September 1998

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Takeda, T., Arima, T. Creep of the beam in Japanese conventional structures composed of green and kiln-dried timber II: predictive model for relative deflections. J Wood Sci 52, 383–388 (2006) doi:10.1007/s10086-002-0797-7

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Key words

  • Mechanosorptive creep
  • Equilibrium moisture content
  • Relative humidity
  • Temperature
  • Shrinkage