Approches expérimentales et numériques pour l'étude des transferts hygroscopiques dans le bois

Abstract : In civil engineering constructions, the development of timber structures requires today to managers works some diagnostic tools and monitoring systems to monitor pathologies (excessive deflections, cracks, biological attack, etc.) but also to control moisture content in the element sections. In the last context, the proposed work in this PhD thesis is the development of a tool for characterization of the moisture content map in the cross sections of structural elements. Studied method is based on the resistivity measuring, comprising a measuring head (resistivity meter) associated with many connected probes in a multiplexed system, and an inverse method implemented in a finite element software. In the first part, it is studied the techniques of characterization of diffusion properties in wood samples characterized by orthotropic and nonlinear behaviors according to average moisture content measurements (gravimetric method) and spatial profiles gamma densitometer measures. It is shown that the coupling of the two measurements provides the intrinsic properties with more reliability and more robustness. The second part deals with the development of an experimental protocol in order to achieve 1D and 2D mapping of the moisture content field in a cross section. The technique is based on the generalization of multiplexed resistivity geophysical methods used in the study of stratified soils with 2-dimensional geometries. The algorithm is based on the coupling between the resistivity measurements and an inverse multiplexed analysis implemented in a finite element code. The 1D solution provides spatial profiles which can replace gamma densitometer measures. For a selected section, 2D profiles allow estimating the moisture content field at any point and thus provide a time tracking of moisture profiles
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Tuan Anh Nguyen. Approches expérimentales et numériques pour l'étude des transferts hygroscopiques dans le bois. Génie civil. Université de Limoges, 2014. Français. ⟨NNT : 2014LIMO0034⟩. ⟨tel-01130828⟩

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