Abstract
Changes in relative humidity of the ambient air, RH (%), cause wetting and drying of wood material, which results in non-uniform moisture contents or moisture gradients, and consequently in moisture-induced stresses and strains in the glued-laminated timber (glulam) members. The aim of the present paper is to perform a hygro-mechanical analysis to predict the mechanical behavior of glulam specimens exposed to two RH regimes, causing wetting from 50% to 90% RH and drying from 90% to 50% RH, and compare the numerical to the experimental results. The aims are also to quantitatively analyze the influence of characteristic material parameters required in the multi-Fickian moisture transport model and the mechanical model on moisture-induced strains and stresses in glulam specimens and to determine the possibility of cracking of the material by analyzing the maximum tensile stresses perpendicular to the grain. Accurate numerical predictions of moisture contents and moisture-induced strains are obtained in the glulam specimens during wetting and drying as compared to the experimental results. The influence of a particular characteristic material parameter on moisture-induced strains and stresses is characterized as significant, but not crucial when a rough numerical estimation of the mechanical behavior of the glulam beam exposed to RH changes is required.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: The financial support by Gunnar Ivarson’s Foundation (Gunnar Ivarsons Stiftelse för Hållbart Samhällsbyggande, GIS) made this work possible. The work of Tomaž Hozjan was supported by the Slovenian Research Agency through the research core funding no. P2-0260, Funder Id: http://dx.doi.org/10.13039/501100004329. The support is gratefully acknowledged.
Employment or leadership: None declared.
Honorarium: None declared.
References
Angst, V., Malo, K.A. (2010) Moisture induced stresses perpendicular to the grain in glulam: review and evaluation of the relative importance of models and parameters. Holzforschung 64:609–617.10.1515/hf.2010.089Search in Google Scholar
Angst, V., Malo, K.A. (2012a) The effect of climate variations on glulam – an experimental study. Eur. J. Wood Prod. 70:603–613.10.1007/s00107-012-0594-ySearch in Google Scholar
Angst, V., Malo, K.A. (2012b) Effect of self-tapping screws on moisture induced stresses in glulam. Eng. Struct. 45:299–306.10.1016/j.engstruct.2012.06.048Search in Google Scholar
Angst, V., Malo, K.A. (2013) Moisture-induced stresses in glulam cross sections during wetting exposures. Wood Sci. Technol. 47:227–241.10.1007/s00226-012-0493-8Search in Google Scholar
Armstrong, L.D., Kingston, R.S.T. (1960) Effect of moisture changes on creep in wood. Nature 185:862–863.10.1038/185862c0Search in Google Scholar
Armstrong, L.D., Christensen, G.N. (1961) Influence of moisture changes on deformation of wood under stress. Nature 191:869–870.10.1038/191869a0Search in Google Scholar
Bengtsson, C. (2001) Mechano-sorptive bending creep of timber – influence of material parameters. Holz. Roh. Werkst. 59:229–236.10.1007/s001070100217Search in Google Scholar
Buck, A.L. (1981) New equations for computing vapor pressure and enhancement factor. J. Appl. Meteorol. 20:1527–1532.10.1175/1520-0450(1981)020<1527:NEFCVP>2.0.CO;2Search in Google Scholar
Caulfield, D.F. (1985) A chemical kinetics approach to the duration-of-load problem in wood. Wood Fiber Sci. 17:504–521.Search in Google Scholar
Dahl, K.B., Malo, K.A. (2009) Nonlinear shear properties of spruce softwood: experimental results. Wood Sci. Technol. 43:539–558.10.1007/s00226-009-0247-4Search in Google Scholar
Danielsson, H. Perpendicular to Grain Fracture Analysis of Wooden Structural Elements, Models and Applications. Lund University, Lund, 2013.Search in Google Scholar
Dietsch, P., Gamper, A., Merk, M., Winter, S. (2015a) Monitoring building climate and timber moisture gradient in large-span timber structures. J. Civ. Struct. Health Monit. 5:153–165.10.1007/s13349-014-0083-6Search in Google Scholar
Dietsch, P., Franke, S., Franke, B., Gamper, A., Winter, S. (2015b) Methods to determine wood moisture content and their applicability in monitoring concepts. J. Civ. Struct. Health Monit. 5:115–127.10.1007/s13349-014-0082-7Search in Google Scholar
Eitelberger, J., Hofstetter, K., Dvinskikh, S.V. (2011) A multi-scale approach for simulation of transient moisture transport processes in wood below the fiber saturation point. Compos. Sci. Technol. 71:1727–1738.10.1016/j.compscitech.2011.08.004Search in Google Scholar
EN 1990 Annex D. Eurocode-basis of Structural Design. Brussels, 2002.Search in Google Scholar
EN 14080 Eurocode-Timber Structures-glued Laminated Timber and Glued Solid Timber. Brussels, 2013.Search in Google Scholar
EN 338 Eurocode-structural Timber-strength classes. Brussels, 2016.Search in Google Scholar
Engelund, E.T., Svensson, S. (2011) Modelling time-dependent mechanical behaviour of softwood using deformation kinetics. Holzforschung 65:231–237.10.1515/hf.2011.011Search in Google Scholar
Fortino, S., Mirianon, F., Toratti, T. (2009) A 3D moisture-stress FEM analysis for time dependent problems in timber structures. Mech. Time-Depend. Mater. 13:333–56.10.1007/s11043-009-9103-zSearch in Google Scholar
Fortino, S., Genoese, A., Genoese, A., Nunes, L., Palma, P. (2013) Numerical modelling of the hygro-thermal response of timber bridges during their service life: a monitoring case-study. Constr. Build. Mater. 47:1225–1234.10.1016/j.conbuildmat.2013.06.009Search in Google Scholar
Fragiacomo, M., Fortino, S., Tononi, D., Usardi, I., Toratti, T. (2011) Moisture-induced stresses perpendicular to grain in cross-sections of timber members exposed to different climates. Eng. Struct. 33:3071–3078.10.1016/j.engstruct.2011.06.018Search in Google Scholar
Frandsen, H.L. Selected Constitutive Models for Simulating the Hygromechanical Response of Wood. Aalborg University, Aalborg, 2007.Search in Google Scholar
Frandsen, H.L., Svensson, S. (2007) Implementation of sorption hysteresis in multi-Fickian moisture transport. Holzforschung 61:693–701.10.1515/HF.2007.113Search in Google Scholar
Frandsen, H.L., Svensson, S., Damkilde, L. (2007a) A hysteresis model suitable for numerical simulation of moisture content in wood. Holzforschung 61:175–181.10.1515/HF.2007.031Search in Google Scholar
Frandsen, H.L., Damkilde, L., Svensson, S. (2007b) A revised multi-Fickian moisture transport model to describe non-Fickian effects in wood. Holzforschung 61:563–572.10.1515/HF.2007.085Search in Google Scholar
Grossman, P.U.A. (1976) Requirements for a model that exhibits mechano-sorptive behaviour. Wood Sci. Technol. 10: 163–168.10.1007/BF00355737Search in Google Scholar
Hailwood, A.J., Horrobin, S. (1946) Absorption of water by polymers: analysis in terms of a simple model. Trans. Faraday Soc. 42:84–92.10.1039/tf946420b084Search in Google Scholar
Hanhijärvi, A. (1995) Deformation kinetics based rheological model for the time-dependent and moisture induced deformation of wood. Wood Sci. Technol. 29:191–199.10.1007/BF00204585Search in Google Scholar
Hanhijärvi, A. (2000) Advances in the knowledge of the influence of moisture changes on the long-term mechanical performance of timber structures. Mater. Struct. 33:43–49.10.1007/BF02481695Search in Google Scholar
Hanhijärvi, A., Mackenzie-Helnwein, P. (2003) Computational analysis of quality reduction during drying of lumber due to irrecoverable deformation. I: orthotropic viscoelastic- mechanosorptive-plastic material model for the transverse plane of wood. J. Eng. Mech. 129:996–1005.10.1061/(ASCE)0733-9399(2003)129:9(996)Search in Google Scholar
Hassani, M.M., Wittel, F.K., Hering, S., Herrman, H.J. (2015) Rheological model for wood. Comput. Methods Appl. Mech. Eng. 283:1032–1060.10.1016/j.cma.2014.10.031Search in Google Scholar
Hearmon, R.F.S., Paton, J.M. (1964) Moisture content changes and creep of wood. Forest Prod. J. 14:357–359.Search in Google Scholar
Hozjan, T., Svensson, S. (2011) Theoretical analysis of moisture transport in wood as an open porous hygroscopic material. Holzforschung 65:97–102.10.1515/hf.2010.122Search in Google Scholar
Huč, S., Svensson, S. (2018a) Influence of grain direction on the time-dependent behavior of wood analyzed by a 3D rheological model. A mathematical consideration. Holzforschung 72:889–897.10.1515/hf-2017-0180Search in Google Scholar
Huč, S., Svensson, S. (2018b) Coupled two-dimensional modeling of viscoelastic creep of wood. Wood Sci. Technol. 52:29–43.10.1007/s00226-017-0944-3Search in Google Scholar
Huč, S., Svensson, S., Hozjan, T. (2018) Hygro-mechanical analysis of wood subjected to constant mechanical load and varying relative humidity. Holzforschung 72:863–870.10.1515/hf-2018-0035Search in Google Scholar
Hunt, D.G. (1989) Linearity and non-linearity in mechano-sorptive creep of softwood in compression and bending. Wood Sci. Technol. 23:323–333.10.1007/BF00353248Search in Google Scholar
Jönsson, J. (2004) Internal stresses in the cross-grain direction in glulam induced by climate variations. Holzforschung 58:154–159.10.1515/HF.2004.023Search in Google Scholar
Jönsson, J. (2005) Internal stresses in glulam due to moisture gradients in the grain direction. Holzforschung 59:18–22.10.1515/HF.2005.003Search in Google Scholar
Jönsson, J., Thelandersson, S. (2003) The effect of moisture gradients on tensile strength perpendicular to grain in glulam. Holz. Roh. Werkst. 61:342–348.10.1007/s00107-003-0405-6Search in Google Scholar
Kollmann, F.F.P., Côté, W.A.Jr. Principles of Wood Science and Technology I, Solid Wood. Springer-Verlag, Berlin, 1968.10.1007/978-3-642-87928-9Search in Google Scholar
Konopka, D., Kaliske, M. (2018) Transient multi-Fickian hygro-mechanical analysis of wood. Comput. Struct. 197:12–27.10.1016/j.compstruc.2017.11.012Search in Google Scholar
Koran, Z. (1979) Tensile properties of spruce under different conditions. Wood Fiber Sci. 11:38–49.Search in Google Scholar
Krabbenhøft, K., Damkilde, L. (2004) A model for non-Fickian moisture transfer in wood. Mater. Struct. 37:615–622.10.1007/BF02483291Search in Google Scholar
Leicester, R.H. (1971) A rheological model for mechano-sorptive deflections of beams. Wood Sci. Technol. 6:272–283.10.1007/BF00353683Search in Google Scholar
Li, H., Perrin, M., Eyma, F., Jacob, X., Gibiat, V. (2018) Moisture content monitoring in glulam structures by embedded sensors via electrical methods. Wood Sci. Technol. 52:733–752.10.1007/s00226-018-0989-ySearch in Google Scholar
Mårtensson, A., Svensson, S. (1997a) Stress-strain relationship of drying wood. 1. Development of a constitutive model. Holzforschung 51:472–478.10.1515/hfsg.1997.51.5.472Search in Google Scholar
Mårtensson, A., Svensson, S. (1997b) Stress-strain relationship of drying wood – Part 2: verification of a one-dimensional model and development of a two-dimensional model. Holzforschung 51:565–570.10.1515/hfsg.1997.51.6.565Search in Google Scholar
Mohager, S., Toratti, T. (1993) Long term bending creep of wood in cyclic relative humidity. Wood Sci. Technol. 27:49–59.10.1007/BF00203409Search in Google Scholar
Ormarsson, S. Numerical Analysis of Moisture-Related Distortions in Sawn Timber. Chalmers University of Technology, Göteborg, 1999.Search in Google Scholar
Ozyhar, T., Mohl, L., Hering, S., Hass, P., Zeindler, L., Ackermann, R., et al. (2016) Orthotropic hygric and mechanical material properties of oak wood. Wood. Mater. Sci. Eng. 11:36–45.10.1080/17480272.2014.941930Search in Google Scholar
Ranta-Maunus, A. (1975) The viscoelasticity of wood at varying moisture content. Wood Sci. Technol. 9:189–205.10.1007/BF00364637Search in Google Scholar
Reichel, S., Kaliske, M. (2015a) Hygro-mechanically coupled modelling of creep in wooden structures, Part II: influence of moisture content. Int. J. Solids Struct. 77:45–64.10.1016/j.ijsolstr.2015.07.029Search in Google Scholar
Reichel, S., Kaliske, M. (2015b) Hygro-mechanically coupled modelling of creep in wooden structures, Part I: mechanics. Int. J. Solids Struct. 77:28–44.10.1016/j.ijsolstr.2015.07.019Search in Google Scholar
Salin, J.G. (1992) Numerical prediction of checking during timber drying and a new mechanosorptive creep model. Holz. Roh. Werkst. 50:195–200.10.1007/BF02663286Search in Google Scholar
Schirmer, R. Die Diffusionszahl von Wasserdampf-Luftgemischen und die Verdampfungsgeschwindigkeit [The diffusion values of water vapor-air mixtures and evaporation rate]. VDI-Verl., Munich, 1938.Search in Google Scholar
Schniewind, A.P. (1966) On the influence of moisture changes in the creep of beech wood perpendicular to the grain including the effects of temperature and temperature change. Holz. Roh. Werkst. 24:87–98.10.1007/BF02608354Search in Google Scholar
Siau, J.F. Wood: Influence of Moisture on Physical Properties. Virginia Polytechnic Institute and State University, Department of Wood Science and Forest Products, Blacksburg, Virginia, 1995.Search in Google Scholar
Skaar, C., Siau, J.F. (1981) Thermal diffusion of bound water in wood. Wood Sci. Technol. 15:105–112.10.1007/BF00367857Search in Google Scholar
Srpčič, S., Srpčič, J., Saje, M., Turk, G. (2009) Mechanical analysis of glulam beams exposed to changing humidity. Wood Sci. Technol. 43:9–22.10.1007/s00226-008-0196-3Search in Google Scholar
Svensson, S., Mårtensson, A. (2002) Simulation of drying stresses in wood. Part II. Convective air drying of sawn timber. Holz. Roh. Werkst 60:72–80.10.1007/s00107-001-0266-9Search in Google Scholar
Svensson, S., Toratti, T. (2002) Mechanical response of wood perpendicular to grain when subjected to changes of humidity. Wood Sci. and Technol. 36:145–156.10.1007/s00226-001-0130-4Search in Google Scholar
Svensson, S., Turk, G., Hozjan, T. (2011) Predicting moisture state of timber members in a continuously varying climate. Eng. Struct. 33:3064–3070.10.1016/j.engstruct.2011.04.029Search in Google Scholar
Turns, S.R. Thermodynamics, Concepts and Applications. Cambridge University Press, New York, 2006.Search in Google Scholar
Zhang, X., Zilling, W., Künzel, H.M., Mitterer, C., Zhang, X. (2016) Combined effects of sorption hysteresis and its temperature dependency on wood materials and building enclosures – Part I: measurements for model validation. Build. Environ. 106:143–154.10.1016/j.buildenv.2016.06.025Search in Google Scholar
©2019 Walter de Gruyter GmbH, Berlin/Boston
Articles in the same Issue
- Frontmatter
- An effective technique for constructing wood composite with superior dimensional stability
- Numerical analysis of moisture-induced strains and stresses in glued-laminated timber
- Contribution of lignin to the stress transfer in compression wood viewed by tensile FTIR loading
- Effect of enzymatic hydrolysis lignin on the mechanical strength and hydrophobic properties of molded fiber materials
- Investigating tool engagement in groundwood pulping: finite element modelling and in-situ observations at the microscale
- Defoliation by insects reduces the wood quality and cellulosic pulp production
- Effect of pulp fibers on the surface softness component of hygiene paper
- Cellulose triacetate from different sources: modification assessment through thermal and chemical characterization
- Incorporation of nano lignin reverse micelles on the transparency, UV-blocking and rheological properties of high-density polyethylene films
- Cellulose nanocrystals/silver nanoparticles: in-situ preparation and application in PVA films
- Larch-derived hierarchical nitrogen-doped carbon with echinus-like architecture for supercapacitor applications
Articles in the same Issue
- Frontmatter
- An effective technique for constructing wood composite with superior dimensional stability
- Numerical analysis of moisture-induced strains and stresses in glued-laminated timber
- Contribution of lignin to the stress transfer in compression wood viewed by tensile FTIR loading
- Effect of enzymatic hydrolysis lignin on the mechanical strength and hydrophobic properties of molded fiber materials
- Investigating tool engagement in groundwood pulping: finite element modelling and in-situ observations at the microscale
- Defoliation by insects reduces the wood quality and cellulosic pulp production
- Effect of pulp fibers on the surface softness component of hygiene paper
- Cellulose triacetate from different sources: modification assessment through thermal and chemical characterization
- Incorporation of nano lignin reverse micelles on the transparency, UV-blocking and rheological properties of high-density polyethylene films
- Cellulose nanocrystals/silver nanoparticles: in-situ preparation and application in PVA films
- Larch-derived hierarchical nitrogen-doped carbon with echinus-like architecture for supercapacitor applications