1 research outputs found
Structural health assessment methodology of a wooden structure of the Heritage : case study of the Villereal Hall
Le diagnostic dâune structure ancienne en bois est une Ă©tape nĂ©cessaire lors dâune restauration ou dâun changement dâusage. De nos jours, lâanalyse mĂ©canique sâintĂšgre dans la mĂ©thodologie de diagnostic. Or cette analyse mĂ©canique est soumise aÌ plusieurs sources dâincertitudes alĂ©atoires et/ou Ă©pistĂ©miques de par la nature mĂȘme du matĂ©riau bois et du caractĂšre alĂ©atoire des charges appliquĂ©es et des conditions environnantes. Cette thĂšse vise aÌ proposer une mĂ©thodologie suffisamment complĂšte de diagnostic de structures du patrimoine bois au travers dâapproches expĂ©rimentales et numĂ©riques en se donnant comme objet dâĂ©tude la halle de VillerĂ©al en Lot-et-Garonne. Les approches expĂ©rimentales sont constituĂ©es de : (i) un examen visuel sur site coupleÌ aÌ des relevĂ©s par scanner 3D, (ii) une campagne dâessais non destructifs (END) rĂ©alisĂ©s in situ sur des Ă©lĂ©ments de la structure pour estimer la masse volumique et le module dâĂ©lasticitĂ© longitudinal du bois et (iii) une sĂ©rie dâessais de caractĂ©risation de chevilles en bois et dâassemblages traditionnels afin de dĂ©terminer leurs propriĂ©tĂ©s mĂ©caniques (rĂ©sistances et raideurs). Les rĂ©sultats de ces campagnes expĂ©rimentales permettent dâalimenter le modĂšle Ă©lĂ©ments finis de la structure en adoptant un comportement Ă©lastique isotrope pour le bois et un comportement non linĂ©aire dissymĂ©trique en traction/compression pour les assemblages. Lâassociation de la mĂ©thode de surfaces de rĂ©ponse (RSM) et des simulations de Monte-Carlo est proposĂ©e pour la propagation dâincertitudes en considĂ©rant la variabilitĂ© des propriĂ©tĂ©s matĂ©rielles (module dâĂ©lasticitĂ©, masse volumique) et dâassemblages (raideurs et rĂ©sistances dâassemblages). La fiabilitĂ© structurale vis-Ă -vis des Ă©tats-limites ultimes et de service est jugĂ©e acceptable selon lâEurocode 0. Enfin, lâĂ©tude de robustesse permet dâĂ©valuer lâeffet de dĂ©gradations dâassemblages sur la fiabilitĂ© de la structure et dâidentifier les assemblages les plus influents sur la robustesse afin de fournir des points de contrĂŽle ou de suivi dans une optique de maintenance de la structure.The diagnosis of an old wooden structure is a necessary step during a restoration or a change of use. Nowadays, the mechanical analysis is integrated in the diagnosis methodology. However, this mechanical analysis is subjected to several sources of random and/or epistemic uncertainties due to the nature of the wood material, randomness of the applied loads and the environmental conditions. This thesis aims at proposing a sufficiently complete methodology for the diagnosis of wooden heritage structures through experimental and numerical approaches, using the Villereal Hall in Lot-et-Garonne as a study case. The experimental approaches were composed of: (i) a visual examination on site coupled with 3D scanner surveys, (ii) a campaign of non-destructive tests (NDT) performed in situ on elements of the structure in order to estimate the density and the longitudinal modulus of elasticity of the wood and (iii) a series of characterization tests of wooden dowels and traditional assemblies in order to determine their mechanical properties (strengths and stiffnesses). The results of these experimental campaigns were used to feed the finite element model of the structure by adopting an isotropic elastic behavior for the wood and a non-linear asymmetric behavior in tension/compression for the connections. The association of the response surface method (RSM) and Monte-Carlo simulations was proposed for the propagation of uncertainties by considering the variability of material properties (modulus of elasticity, density) and connections (stiffnesses and strengths of connections). The structural reliability with respect to the ultimate and serviceability limit states was judged acceptable according to Eurocode 0. Finally, the robustness study allows the evaluation of the effect of assembly degradations on the reliability of the structure and to identify the most influential assemblies on the robustness in order to provide control or monitoring points for the maintenance of the structure