Moisture content monitoring in glulam structures by embedded sensors via electrical methods

Li, Hang; Perrin, Marianne; Eyma, Florent; Jacob, Xavier; Gibiat, Vincent

doi:10.1007/s00226-018-0989-y

Cited by 19 publications

(16 citation statements)

References 24 publications

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“…The mathematical relationship between the resistance and MC proposed by Forsén and Tarvainen (2000) more suitably fitted the experimental values than that suggested by Skaar (1988). However, Li et al (2018) determined a satisfactory overlap with the latter's proposed relationship. The fit is material-related and therefore, the range of validity and possible errors constitute relevant information for the future publication of curves fitting resistance with MC.…”

Section: Electrical Resistance Methodsmentioning

confidence: 73%

“…The advantage of the electric resistance method is that it is more robust and can be used in the over-hygroscopic range (Li et al 2018). However, Niklewski (2018) stated large uncertainties and inaccurate MC measurements when using the electrical resistance methods in the overhygroscopic range.…”

Section: Comparison Between Electrical Resistance Methods and Sorption Methodsmentioning

confidence: 99%

“…MC is usually monitored using either electrical resistance or sorption methods (also known as the bore hole method) for ensuring a reliable moisture development measurement of the structure (Dietsch et al 2015a, Li et al 2018. As each of these methods have their own advantages and disadvantages, both are sometimes installed simultaneously (Franke et al 2019).…”

Section: Introductionmentioning

confidence: 99%

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Calibration and comparison of two moisture content measurement methods for in situ monitoring of beech laminated veneer lumber

Schiere

Franke

et al. 2021

Wood Material Science & Engineering

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A timber bridge constructed in 1815 was renovated in 2018, wherein the load-bearing system was reinforced with beech laminated veneer lumber (LVL) elements. Beech LVL is primarily found in dry and heated structures (Service Class 1). Although the material of this bridge would not be directly exposed to weather, it would be exposed to outdoor relative humidity ranging between 50% in spring and 90% or higher in autumn (Service Class 2). Thus, the moisture content development in the reinforcements was monitored to observe the response of the material under such conditions. The moisture content was measured using both sorptive and electrical resistance methods. The relationship between the electrical resistance of the material to moisture content and sorption isotherms was determined through laboratory experiments. Thereafter, the derived relationships were used to determine the moisture content measured on the bridge over a period of two years. Consequently, the two measurement methods resulted in overlapping of moisture content values, which remained within safe levels and are expected to be maintained in future. The overlapping moisture content measurements validated that either of the monitoring methods could be independently deployed to obtain reliable results.

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Section: Electrical Resistance Methodsmentioning

confidence: 73%

Section: Comparison Between Electrical Resistance Methods and Sorption Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Calibration and comparison of two moisture content measurement methods for in situ monitoring of beech laminated veneer lumber

Schiere

Franke

et al. 2021

Wood Material Science & Engineering

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“…The MC of wood can be determined using different methods, amongst which the electrical resistance method (measured between two electrodes) and the sorption method (the measurement of climate in a void) are the most common [1,9,10,22,24,[30][31][32][33][34][35][36][37][38] (Figure 4). The accuracy of the electrical resistance method depends on the wood species and lies between 1 and 2 M% [30].…”

Section: Monitoring Moisture Content Methodsmentioning

confidence: 99%

Comparison between Predicted and Measured Moisture Content and Climate in 12 Monitored Timber Structures in Switzerland

Schiere

Franke

et al. 2021

Buildings

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Wood is a hygroscopic material that primarily adapts its moisture content to the surrounding relative humidity. The climate in a structure or building depends on the building type and the region the structure is located in. In this study, the effect of region on the moisture content of wood was investigated. Measurements taken in 12 ventilated timber structures were compared to the theoretical equilibrium moisture content calculated from the relative humidity and temperature in 107 meteorological stations across Switzerland. The monitored load-bearing elements were made of softwood and protected from the direct impact of weather. The climatic conditions around the Alps, a mountain range that runs from France to Austria and crosses Switzerland, can be divided into the following three different regions: (1) south of the Alps, where the climate is affected mainly by the Mediterranean sea; (2) north of the Alps, where the climate is affected by the Atlantic Ocean; and (3) the inner Alps, where the climate is considered to be relatively dry. The climatic conditions of the three separate regions were reflected in the measurements made in the monitored timber structures. Differences between the regions were quantified. The moisture content and relative humidity, similarly to temperature, depended on altitude (above sea level).

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“…The influence of different moisture contents on the mechanical behavior of timber members has to be known to avoid cracking, to improve the performance of timber structures, as well as to improve methods for monitoring and maintenance of timber structures, for example, sensor-based monitoring (Fortino et al 2013) and coating-based maintenance (Fragiacomo et al 2011). Several methods are used for monitoring moisture contents in the glulam members (Dietsch et al 2015b;Li et al 2018). Based on measurements of a mid-span deflection of a glulam beam (Mohager and Toratti 1993;Srpčič et al 2009) or a uniaxial deformation of small glulam specimens (Jönsson and Thelandersson 2003;Jönsson 2004Jönsson , 2005Angst and Malo 2012a,b), a mechanical state of the glulam members is determined.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of moisture-induced strains and stresses in glued-laminated timber

2019

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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.

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Moisture content monitoring in glulam structures by embedded sensors via electrical methods

Cited by 19 publications

References 24 publications

Calibration and comparison of two moisture content measurement methods for in situ monitoring of beech laminated veneer lumber

Calibration and comparison of two moisture content measurement methods for in situ monitoring of beech laminated veneer lumber

Comparison between Predicted and Measured Moisture Content and Climate in 12 Monitored Timber Structures in Switzerland

Numerical analysis of moisture-induced strains and stresses in glued-laminated timber

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