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P. 40
erical simulation of moisture transport in thermally modified wood
exposed to rain
Stefania Fortino1, Petr Hradil1, Tuuli Uimonen2
1 VTT Technical Research Centre of Finland Ltd, stefania.fortino@vtt.fi, petr.hradil@vtt.fi
2 Jartek Invest Oy, tuuli.uimonen@jartek.fi
Renewable wooden products exposed to continuously variable outdoor climates are strongly
affected by the moisture levels in the material. High moisture contents accumulated in wood
during long periods, in combination with favorable temperatures, represent a risk for the
durability of thermally modified wood products because of decay development. In this context,
numerical simulations can quickly predict the high levels of moisture as well as the related risk
of decay in decking products for buildings. This information can help to optimize the product
maintenance, for example, suggesting the use of appropriate coatings. Earlier studies by the
first author have shown that the single-phase finite element modelling of moisture diffusion in
untreated wood is an efficient tool to simulate the moisture transport in wooden components
of buildings sheltered from rain (Fragiacomo et al. 2011). An extension of this approach, which
takes into account the effect of rain in thermally modified products, is proposed in the present
paper. The sorption isotherms used in the model are measured at different temperatures above
zero degrees Celsius within this research. In addition, the diffusion coefficient includes the
contribution of free water in wood above the fiber saturation point. A case study of thermally
modified wood is numerically analyzed, and the results in terms of moisture content are
compared with data taken from previous research (Metsä-Korteläinen et al. 2011). In future
work, the proposed moisture transport model will be combined with well-assessed models for
wood decay (Brischke and Meyer-Veltrup 2016).
Keywords: thermally modified wood, moisture transport, rain effect
Acknowledgements: The authors would like to thank project DigiMoist1 (A Digital end-user
toolset for Moisture assessment in Wooden buildings – 1st part: Hygro-thermal database),
funded by the Finnish Ministry of the Environment within the “Wood Building Action Plan”,
and project Click Design (Delivering fingertip knowledge to enable service life performance
specification of wood), funded within the ForestValue Research Programme.
REFERENCES
Fragiacomo M., Fortino S., Tononi D., Usardi I., Toratti T. (2011) Moisture-induced stresses perpendicular to grain in
timber sections exposed to European climates. Engineering Structures 33 (11): 3071–3078.
Metsä-Kortelainen S., Paajanen L., Viitanen H. (2011) Durability of thermally modified Nor-way spruce and Scots
pine in above-ground conditions. Wood Material Science and Engineer-ing, 6: 163–169
Brischke C. and Meyer-Veltrup L. (2016) Modelling timber decay caused by brown rot fungi. Materials and Structures
49:3281–3291.
INNORENEW COE INTERNATIONAL CONFERENCE 2020
40
exposed to rain
Stefania Fortino1, Petr Hradil1, Tuuli Uimonen2
1 VTT Technical Research Centre of Finland Ltd, stefania.fortino@vtt.fi, petr.hradil@vtt.fi
2 Jartek Invest Oy, tuuli.uimonen@jartek.fi
Renewable wooden products exposed to continuously variable outdoor climates are strongly
affected by the moisture levels in the material. High moisture contents accumulated in wood
during long periods, in combination with favorable temperatures, represent a risk for the
durability of thermally modified wood products because of decay development. In this context,
numerical simulations can quickly predict the high levels of moisture as well as the related risk
of decay in decking products for buildings. This information can help to optimize the product
maintenance, for example, suggesting the use of appropriate coatings. Earlier studies by the
first author have shown that the single-phase finite element modelling of moisture diffusion in
untreated wood is an efficient tool to simulate the moisture transport in wooden components
of buildings sheltered from rain (Fragiacomo et al. 2011). An extension of this approach, which
takes into account the effect of rain in thermally modified products, is proposed in the present
paper. The sorption isotherms used in the model are measured at different temperatures above
zero degrees Celsius within this research. In addition, the diffusion coefficient includes the
contribution of free water in wood above the fiber saturation point. A case study of thermally
modified wood is numerically analyzed, and the results in terms of moisture content are
compared with data taken from previous research (Metsä-Korteläinen et al. 2011). In future
work, the proposed moisture transport model will be combined with well-assessed models for
wood decay (Brischke and Meyer-Veltrup 2016).
Keywords: thermally modified wood, moisture transport, rain effect
Acknowledgements: The authors would like to thank project DigiMoist1 (A Digital end-user
toolset for Moisture assessment in Wooden buildings – 1st part: Hygro-thermal database),
funded by the Finnish Ministry of the Environment within the “Wood Building Action Plan”,
and project Click Design (Delivering fingertip knowledge to enable service life performance
specification of wood), funded within the ForestValue Research Programme.
REFERENCES
Fragiacomo M., Fortino S., Tononi D., Usardi I., Toratti T. (2011) Moisture-induced stresses perpendicular to grain in
timber sections exposed to European climates. Engineering Structures 33 (11): 3071–3078.
Metsä-Kortelainen S., Paajanen L., Viitanen H. (2011) Durability of thermally modified Nor-way spruce and Scots
pine in above-ground conditions. Wood Material Science and Engineer-ing, 6: 163–169
Brischke C. and Meyer-Veltrup L. (2016) Modelling timber decay caused by brown rot fungi. Materials and Structures
49:3281–3291.
INNORENEW COE INTERNATIONAL CONFERENCE 2020
40
