An experimental and numerical study of moisture transport and moisture-induced strain in fast-grown sitka spruce

  • Conan O’Ceallaigh
  • Karol Sikora
  • Daniel McPolin
  • Annette M. Harte
Keywords: Adsorption, desorption, finite element analysis, glued laminated timber, long-term moisture, long-term moisture transport, moisture diffusion

Abstract

The use of fast-grown timber in the manufacture of engineered wood products is increasing; however, the fast growth rate results in a low-density timber that is susceptible to significant swelling and shrinkage deformations under changing moisture content. The current study focuses on the characterisation of the moisture diffusion and swelling/shrinkage of fast-grown Sitka spruce and the prediction of the moisture-induced strain development in Sitka spruce glulam beams under variable humidity cycles. Moisture content evolution and swelling/shrinkage coefficients were measured and the longitudinal swelling/shrinkage was found to be significantly greater than for slow-grown timber. Sitka spruce glued-laminated beams were subjected to controlled relative humidity cycling for 52 weeks and the moisture distribution and moisture-induced strains were measured continuously. Coupled moisture-displacement numerical models, incorporating the experimentally measured material parameters were developed. The effect of the glue-line was found to have an insignificant effect on moisture transport, however, the material orientation greatly influenced the predicted moisture-induced strain. Accurately mapping the material orientation produced significantly better predictions of the experimental results over the 52-week period.

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Published
2018-07-23
How to Cite
O’Ceallaigh, C., Sikora, K., McPolin, D., & M. Harte, A. (2018). An experimental and numerical study of moisture transport and moisture-induced strain in fast-grown sitka spruce. Maderas. Ciencia Y Tecnología, 21(1). Retrieved from http://revistas.ubiobio.cl/index.php/MCT/article/view/3294