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A multiscale model for modulus of elasticity of concrete at high temperatures / Jaesung Lee in Cement and concrete research, Vol. 39 N° 9 (Septembre 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 9 (Septembre 2009) . - pp. 754–762 Titre : A multiscale model for modulus of elasticity of concrete at high temperatures Type de document : texte imprimé Auteurs : Jaesung Lee, Auteur ; Xi, Yunping, Auteur ; Kaspar Willam, Auteur Année de publication : 2009 Article en page(s) : pp. 754–762 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Composite  mechanics;  Modulus  of  elasticity;  High  temperature;  Concrete Résumé : In this paper, the thermal degradation of modulus of elasticity of concrete is modeled by composite mechanics at three scales of observation: (a) at the level of concrete, (b) at the level of mortar, and (c) the cement paste level. At the latter, the change of volume fractions of the constituents are evaluated based on phase transformations which take place in different temperature ranges. Stoichiometric models are used to determine the volume changes of the constituents. At the mortar and concrete levels, the temperature dependence of fine and coarse aggregates is considered based on available test data. The multiscale chemo-mechanical model can be used to predict the temperature dependence and thermal degradation of the elastic concrete modulus. The model predictions are compared with test data in the literature as well as in-house test data. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001227 [article] A multiscale model for modulus of elasticity of concrete at high temperatures [texte imprimé] / Jaesung Lee, Auteur ; Xi, Yunping, Auteur ; Kaspar Willam, Auteur . - 2009 . - pp. 754–762. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 9 (Septembre 2009) . - pp. 754–762 Mots-clés : Composite  mechanics;  Modulus  of  elasticity;  High  temperature;  Concrete Résumé : In this paper, the thermal degradation of modulus of elasticity of concrete is modeled by composite mechanics at three scales of observation: (a) at the level of concrete, (b) at the level of mortar, and (c) the cement paste level. At the latter, the change of volume fractions of the constituents are evaluated based on phase transformations which take place in different temperature ranges. Stoichiometric models are used to determine the volume changes of the constituents. At the mortar and concrete levels, the temperature dependence of fine and coarse aggregates is considered based on available test data. The multiscale chemo-mechanical model can be used to predict the temperature dependence and thermal degradation of the elastic concrete modulus. The model predictions are compared with test data in the literature as well as in-house test data. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001227

Question of tension softening versus tension stiffening in plain and reinforced concrete / Bernd Koeberl in Journal of engineering mechanics, Vol. 134 n°9 (Septembre 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°9 (Septembre 2008) . - pp.804–808. Titre : Question of tension softening versus tension stiffening in plain and reinforced concrete Type de document : texte imprimé Auteurs : Bernd Koeberl, Auteur ; Kaspar Willam, Auteur Année de publication : 2008 Article en page(s) : pp.804–808. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Bonding  Reinforced  concrete  Cracking  Computer  models  Failure  modes  Shear  failure  Tension Résumé : Stress transfer from concrete into steel is one of the fundamental mechanisms behind the significant ductility of reinforced concrete. Considering the low value of cracking strain of plain concrete, it is the stress transfer that takes place during debonding when the steel strain approaches the yield limit at a level which is an order of magnitude larger than the cracking limit of concrete. This technical note examines the difference of “tension softening” of plain concrete versus “tension stiffening” of reinforced concrete which describes the stress transfer mechanism from concrete into the embedded reinforcing bars. Using three-dimensional finite-element simulations the fracture energy arguments of Mode I versus Mode II are reexamined when the axial response behavior of plain concrete in tension softening is compared with that of reinforced concrete exhibiting tension stiffening in long and short tension members. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A9%2880 [...] [article] Question of tension softening versus tension stiffening in plain and reinforced concrete [texte imprimé] / Bernd Koeberl, Auteur ; Kaspar Willam, Auteur . - 2008 . - pp.804–808. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°9 (Septembre 2008) . - pp.804–808. Mots-clés : Bonding  Reinforced  concrete  Cracking  Computer  models  Failure  modes  Shear  failure  Tension Résumé : Stress transfer from concrete into steel is one of the fundamental mechanisms behind the significant ductility of reinforced concrete. Considering the low value of cracking strain of plain concrete, it is the stress transfer that takes place during debonding when the steel strain approaches the yield limit at a level which is an order of magnitude larger than the cracking limit of concrete. This technical note examines the difference of “tension softening” of plain concrete versus “tension stiffening” of reinforced concrete which describes the stress transfer mechanism from concrete into the embedded reinforcing bars. Using three-dimensional finite-element simulations the fracture energy arguments of Mode I versus Mode II are reexamined when the axial response behavior of plain concrete in tension softening is compared with that of reinforced concrete exhibiting tension stiffening in long and short tension members. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A9%2880 [...]