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Modélisation du comportement mécanique d'assemblages bois avec prise en compte de critères de rupture

Abstract : The dowel-type connections largely used in the timber structures are designed to transmit shear forces and bending moments between the assembled elements such as the columns and the beams in the traditional portal frames. For this type of connection, the timber-to-timber joints are often used with or without reinforcement by glued plywood plates or other materials. Complying with the actual architectural trends, the high strength requirements and fire behaviour, the timber-to-timber joints are often replaced by the steel-to-timber joints where the steel plate is protected by the timber elements. Tests were performed on the multiple-dowel steel-to-timber joints loaded by tension parallel and perpendicular to grain and bending. From these results, a three-dimensional finite element model was developed using the following hypotheses: a non-linear elasto-plastic material law for steel, the laws of contact and friction between the dowels and the timber and an elastic perfectly plastic law for timber on the basis of the Hill criterion associated with or without the Hoffman criterion which represents the failure of timber. For the modelling of timber material, which is the most difficult part of modelling, various approaches are used in the literature. These models were often based on criteria of anisotropic plasticity such as Hill. However, this criterion does not take into account the asymmetry mechanical behaviour of timber material in tension and compression. Besides, it dose not consider brittle behaviour of material in tension perpendicular to grain and in shear. To fill the gaps, the Hill criterion is associated with the Hoffman failure criterion which represents the damage evolution of the timber by a reduction of the elastic modulus. This criterion is particularly suited to the brittle tension behaviour in the direction perpendicular to grain. Thus, the Hill criterion controls the plasticity accepted well for the timber wood loaded in compression and the Hoffman criterion is used to represent the brittle behaviour of timber in certain directions. The comparison between the experimental and numerical results shows that the proposed modelling is in good agreement with experimental results. The validated model is used for the parametric study on the geometry of timber joints. On basis of numerical results, the analytical models predicting the behaviour of joints are proposed or verified.
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Submitted on : Friday, August 24, 2012 - 2:52:16 PM
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  • HAL Id : tel-00725264, version 1

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Bohan Xu. Modélisation du comportement mécanique d'assemblages bois avec prise en compte de critères de rupture. Génie des procédés. Université Blaise Pascal - Clermont-Ferrand II, 2009. Français. ⟨NNT : 2009CLF21956⟩. ⟨tel-00725264⟩

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