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Simple homogenized model for the nonlinear analysis of FRP-strengthened masonry structures. I / Gabriele Milani in Journal of engineering mechanics, Vol. 139 N° 1 (Janvier 2013) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 139 N° 1 (Janvier 2013) . - pp.59–76 Titre : Simple homogenized model for the nonlinear analysis of FRP-strengthened masonry structures. I : Theory Type de document : texte imprimé Auteurs : Gabriele Milani, Auteur ; Paulo B. Lourenco, Auteur Année de publication : 2013 Article en page(s) : pp.59–76 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Masonry  Simplified  homogenization  Nonlinear  model  SQP  approach  3D  structural  analysis Résumé : A suitable and simple two-step model able to predict the nonlinear response of fiber-reinforced polymer (FRP)-strengthened three-dimensional masonry structures is presented. In the first step, nonstrengthened masonry is substituted by a macroscopically equivalent homogeneous material through a kinematic model based on finite elements and working on a heterogeneous assemblage of blocks. Nonlinearity is concentrated exclusively on joints reduced to interfaces exhibiting a frictional behavior with limited tensile and compressive strength with softening. The homogenized stress-strain behavior evaluated at the mesoscale is then implemented at a structural level in a finite-element nonlinear code, relying on an assemblage of rigid infinitely resistant six-noded wedge elements and nonlinear interfaces, exhibiting deterioration of the mechanical properties. The FRP-reinforcing strips are modeled through rigid triangles and nonlinear interfaces between adjoining triangles. Delamination from the support is accounted for by modeling the FRP-masonry bond by means of nonlinear softening triangular interfaces. Italian code formulas are used to evaluate peak interface tangential strength and postpeak behavior. In this first part, the theoretical basis of the model and the nonlinear stress-strain behavior at a cell level are discussed. Structural examples will be analyzed in the accompanying paper devoted to the structural scale. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000457 [article] Simple homogenized model for the nonlinear analysis of FRP-strengthened masonry structures. I : Theory [texte imprimé] / Gabriele Milani, Auteur ; Paulo B. Lourenco, Auteur . - 2013 . - pp.59–76. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 139 N° 1 (Janvier 2013) . - pp.59–76 Mots-clés : Masonry  Simplified  homogenization  Nonlinear  model  SQP  approach  3D  structural  analysis Résumé : A suitable and simple two-step model able to predict the nonlinear response of fiber-reinforced polymer (FRP)-strengthened three-dimensional masonry structures is presented. In the first step, nonstrengthened masonry is substituted by a macroscopically equivalent homogeneous material through a kinematic model based on finite elements and working on a heterogeneous assemblage of blocks. Nonlinearity is concentrated exclusively on joints reduced to interfaces exhibiting a frictional behavior with limited tensile and compressive strength with softening. The homogenized stress-strain behavior evaluated at the mesoscale is then implemented at a structural level in a finite-element nonlinear code, relying on an assemblage of rigid infinitely resistant six-noded wedge elements and nonlinear interfaces, exhibiting deterioration of the mechanical properties. The FRP-reinforcing strips are modeled through rigid triangles and nonlinear interfaces between adjoining triangles. Delamination from the support is accounted for by modeling the FRP-masonry bond by means of nonlinear softening triangular interfaces. Italian code formulas are used to evaluate peak interface tangential strength and postpeak behavior. In this first part, the theoretical basis of the model and the nonlinear stress-strain behavior at a cell level are discussed. Structural examples will be analyzed in the accompanying paper devoted to the structural scale. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000457

Simple homogenized model for the nonlinear analysis of FRP-strengthened masonry structures. II / Gabriele Milani in Journal of engineering mechanics, Vol. 139 N° 1 (Janvier 2013) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 139 N° 1 (Janvier 2013) . - pp.77–93. Titre : Simple homogenized model for the nonlinear analysis of FRP-strengthened masonry structures. II : Structural applications Type de document : texte imprimé Auteurs : Gabriele Milani, Auteur ; Paulo B. Lourenco, Auteur Année de publication : 2013 Article en page(s) : pp.77–93. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Masonry  FRP  strengthening  Nonlinear  behavior  In-  and  out-of-plane  loads  3D  structural  analysis  Curved  shells Résumé : The homogenized masonry nonlinear stress-strain curves obtained through the simple micromechanical model developed in the first part of the paper are here used for the analysis of strengthened masonry walls under various loading conditions. In particular, a deep beam and a shear wall strengthened with fiber-reinforced polymer (FRP) strips are analyzed for masonry loaded in-plane. Additionally, single and double curvature masonry structures strengthened in various ways, namely a circular arch with buttresses and a ribbed cross vault, are considered. For all the examples presented, both the nonstrengthened and FRP–strengthened cases are discussed. Additional nonlinear finite-element analyses are performed, modeling masonry through an equivalent macroscopic material with softening to assess the present model predictions. Detailed comparisons between the experimental data, where available, and numerical results are also presented. The examples show the efficiency of the homogenized technique with respect to (1) accuracy of the results; (2) low number of finite elements required; and (3) independence of the mesh at a structural level from the actual texture of masonry. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000479 [article] Simple homogenized model for the nonlinear analysis of FRP-strengthened masonry structures. II : Structural applications [texte imprimé] / Gabriele Milani, Auteur ; Paulo B. Lourenco, Auteur . - 2013 . - pp.77–93. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 139 N° 1 (Janvier 2013) . - pp.77–93. Mots-clés : Masonry  FRP  strengthening  Nonlinear  behavior  In-  and  out-of-plane  loads  3D  structural  analysis  Curved  shells Résumé : The homogenized masonry nonlinear stress-strain curves obtained through the simple micromechanical model developed in the first part of the paper are here used for the analysis of strengthened masonry walls under various loading conditions. In particular, a deep beam and a shear wall strengthened with fiber-reinforced polymer (FRP) strips are analyzed for masonry loaded in-plane. Additionally, single and double curvature masonry structures strengthened in various ways, namely a circular arch with buttresses and a ribbed cross vault, are considered. For all the examples presented, both the nonstrengthened and FRP–strengthened cases are discussed. Additional nonlinear finite-element analyses are performed, modeling masonry through an equivalent macroscopic material with softening to assess the present model predictions. Detailed comparisons between the experimental data, where available, and numerical results are also presented. The examples show the efficiency of the homogenized technique with respect to (1) accuracy of the results; (2) low number of finite elements required; and (3) independence of the mesh at a structural level from the actual texture of masonry. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000479