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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Authors: | Takashi Takeda Takanori Arima |
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Institution: | (1) Faculty of Agriculture, Shinshu University, 8304 Minamiminowamura, Nagano 399-4598, Japan;(2) Miyazaki Prefectural Wood Utilization Research Center, Miyakonojo, Miyazaki 885-0037, Japan |
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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.
Part of this article was presented at the Annual Meeting of the Architectural Institute of Japan, Kyushu, September 1998 |
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Keywords: | Mechanosorptive creep Equilibrium moisture content Relative humidity Temperature Shrinkage |
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