Effects of early-age thermal behaviour on damage risks in massive concrete structures / Matthieu Briffaut in European journal of environmental and civil engineering, Vol. 16 N° 5 (Mai 2012)  

Public ISBD [article]  inEuropean journal of environmental and civil engineering > Vol. 16 N° 5 (Mai 2012) . - pp. 589-605 Titre : Effects of early-age thermal behaviour on damage risks in massive concrete structures Type de document : texte imprimé Auteurs : Matthieu Briffaut, Auteur ; Benboudjema, Farid, Auteur ; Torrenti, Jean-Michel, Auteur Année de publication : 2012 Article en page(s) : pp. 589-605 Note générale : Génie Civil Langues : Français (fre) Mots-clés : Early age Thermal properties Concrete Massive structures Résumé : At early age, temperature in massive concrete structures may reach over 70°C because hydration is an exothermic chemical reaction. Temperature evolution (increasing followed by decreasing temperature) can lead to damage risks in the short and long term. Firstly, cracking due to self-restrained strains (essentially thermal strains) can occur (which increase the transport properties and so the kinetics of degradation); and secondly, delayed ettringite formation can appear. In addition, if autogenous and thermal strains are restrained, compressive stresses and then tensile stresses increase, which can cause crossing cracks. However, this paper will not deal with these phenomena. In the first part, sensitivity to delayed ettringite formation and early age cracks by self-restrained strains are studied with regards to the environmental conditions by a numerical approach. This part shows that the external temperature has a significant impact on the maximal temperature reached, but that the temperature difference between the core and the surface is mainly impacted by the wind velocity. Then, a parametric study on the effect of the variation of thermal properties at early age has been achieved and shows that it needs to be taken into account. Finally, visco-elastic mechanical calculations show the impact of thermal property variation on the stresses generated by self restraint. DEWEY : 624 ISSN : 1964-8189 En ligne : http://www.tandfonline.com/doi/abs/10.1080/19648189.2012.668016 [article] Effects of early-age thermal behaviour on damage risks in massive concrete structures [texte imprimé] / Matthieu Briffaut, Auteur ; Benboudjema, Farid, Auteur ; Torrenti, Jean-Michel, Auteur . - 2012 . - pp. 589-605. Génie Civil Langues : Français (fre) in European journal of environmental and civil engineering > Vol. 16 N° 5 (Mai 2012) . - pp. 589-605 Mots-clés : Early age Thermal properties Concrete Massive structures Résumé : At early age, temperature in massive concrete structures may reach over 70°C because hydration is an exothermic chemical reaction. Temperature evolution (increasing followed by decreasing temperature) can lead to damage risks in the short and long term. Firstly, cracking due to self-restrained strains (essentially thermal strains) can occur (which increase the transport properties and so the kinetics of degradation); and secondly, delayed ettringite formation can appear. In addition, if autogenous and thermal strains are restrained, compressive stresses and then tensile stresses increase, which can cause crossing cracks. However, this paper will not deal with these phenomena. In the first part, sensitivity to delayed ettringite formation and early age cracks by self-restrained strains are studied with regards to the environmental conditions by a numerical approach. This part shows that the external temperature has a significant impact on the maximal temperature reached, but that the temperature difference between the core and the surface is mainly impacted by the wind velocity. Then, a parametric study on the effect of the variation of thermal properties at early age has been achieved and shows that it needs to be taken into account. Finally, visco-elastic mechanical calculations show the impact of thermal property variation on the stresses generated by self restraint. DEWEY : 624 ISSN : 1964-8189 En ligne : http://www.tandfonline.com/doi/abs/10.1080/19648189.2012.668016

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Influence of the spatial variability of leaching kinetics parameters on the lifespan of a concrete structure / Thomas de Larrard in European journal of environmental and civil engineering, Vol. 16 N° 5 (Mai 2012)  

Public ISBD [article]  inEuropean journal of environmental and civil engineering > Vol. 16 N° 5 (Mai 2012) . - pp. 606-624 Titre : Influence of the spatial variability of leaching kinetics parameters on the lifespan of a concrete structure Type de document : texte imprimé Auteurs : Thomas de Larrard, Auteur ; Benboudjema, Farid, Auteur ; Jean-Baptiste Colliat, Auteur Année de publication : 2012 Article en page(s) : pp. 606-624 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Leaching Porosity Tortuosity Variability Distribution Correlation length Karhunen--Loève expansion Monte Carlo method Résumé : This works aims at studying, through the Monte Carlo method, the influence of the leaching kinetics parameters spatial variability on the lifespan of a concrete structure. The considered structure is a tunnel for nuclear waste storage. It is observed that the expected value for the lifespan estimated when considering the material spatial variability is significantly lower than the lifespan estimated with a single simulation considering uniform parameter fields, equal to the expected value for each parameter. DEWEY : 624 ISSN : 1964-8189 En ligne : http://www.tandfonline.com/doi/abs/10.1080/19648189.2012.671048 [article] Influence of the spatial variability of leaching kinetics parameters on the lifespan of a concrete structure [texte imprimé] / Thomas de Larrard, Auteur ; Benboudjema, Farid, Auteur ; Jean-Baptiste Colliat, Auteur . - 2012 . - pp. 606-624. Génie Civil Langues : Anglais (eng) in European journal of environmental and civil engineering > Vol. 16 N° 5 (Mai 2012) . - pp. 606-624 Mots-clés : Leaching Porosity Tortuosity Variability Distribution Correlation length Karhunen--Loève expansion Monte Carlo method Résumé : This works aims at studying, through the Monte Carlo method, the influence of the leaching kinetics parameters spatial variability on the lifespan of a concrete structure. The considered structure is a tunnel for nuclear waste storage. It is observed that the expected value for the lifespan estimated when considering the material spatial variability is significantly lower than the lifespan estimated with a single simulation considering uniform parameter fields, equal to the expected value for each parameter. DEWEY : 624 ISSN : 1964-8189 En ligne : http://www.tandfonline.com/doi/abs/10.1080/19648189.2012.671048

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Structural Effects of Drying Shrinkage / Benboudjema, Farid in Journal of engineering mechanics, Vol.131, N°11 (Novembre 2005)

Public ISBD [article]  inJournal of engineering mechanics > Vol.131, N°11 (Novembre 2005) . - 1195-1199 p. Titre : Structural Effects of Drying Shrinkage Titre original : Effets Structuraux de Sécher le Rétrécissement Type de document : texte imprimé Auteurs : Benboudjema, Farid, Auteur ; Meftah, Fékri, Auteur ; Torrenti, Jean-Michel ; Sture, Stein, Éditeur scientifique Année de publication : 2005 Article en page(s) : 1195-1199 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Concrete Dewatering Shrinkage Cracking Finite element method Asséchage Rétrécissement Fendre Méthode d'élément fini Index. décimale : 621.34 Résumé : Predicting delayed strains in concrete proves to be critical to a large number of prestressed concrete structures. These delayed strain include drying shrinkage, basic, and drying creep strains essentially. In this paper, a model for identifying structural effects, due to cracking, on the behavior of drying concrete is presented. Existing experimental results are used in order to display the frontier between the intrinsic behavior of the material and the structural effects when concerned by drying shrinkage. La prévision des contraintes retardées en béton s'avère critique à un grand nombre de structures en béton précontraintes. Celles-ci contrainte retardée incluent le rétrécissement de séchage, de base, et séchant des contraintes de fluage essentiellement. En cet article, un modèle pour identifier des effets structuraux, dû à fendre, sur le comportement du béton de séchage est présenté. Des résultats expérimentaux existants sont employés afin de montrer la frontière entre le comportement intrinsèque du matériel et les effets structuraux une fois concernés par rétrécissement de séchage. [article] Structural Effects of Drying Shrinkage = Effets Structuraux de Sécher le Rétrécissement [texte imprimé] / Benboudjema, Farid, Auteur ; Meftah, Fékri, Auteur ; Torrenti, Jean-Michel ; Sture, Stein, Éditeur scientifique . - 2005 . - 1195-1199 p. Génie Mécanique Langues : Anglais (eng) in Journal of engineering mechanics > Vol.131, N°11 (Novembre 2005) . - 1195-1199 p. Mots-clés : Concrete Dewatering Shrinkage Cracking Finite element method Asséchage Rétrécissement Fendre Méthode d'élément fini Index. décimale : 621.34 Résumé : Predicting delayed strains in concrete proves to be critical to a large number of prestressed concrete structures. These delayed strain include drying shrinkage, basic, and drying creep strains essentially. In this paper, a model for identifying structural effects, due to cracking, on the behavior of drying concrete is presented. Existing experimental results are used in order to display the frontier between the intrinsic behavior of the material and the structural effects when concerned by drying shrinkage. La prévision des contraintes retardées en béton s'avère critique à un grand nombre de structures en béton précontraintes. Celles-ci contrainte retardée incluent le rétrécissement de séchage, de base, et séchant des contraintes de fluage essentiellement. En cet article, un modèle pour identifier des effets structuraux, dû à fendre, sur le comportement du béton de séchage est présenté. Des résultats expérimentaux existants sont employés afin de montrer la frontière entre le comportement intrinsèque du matériel et les effets structuraux une fois concernés par rétrécissement de séchage.

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Uncertainty propagation on damage evolution of a concrete structure subjected to coupled leaching and creep / Thomas de Larrard in European journal of environmental and civil engineering, Vol. 14 N° 6-7 (Juin 2010)  

Public ISBD [article]  inEuropean journal of environmental and civil engineering > Vol. 14 N° 6-7 (Juin 2010) . - pp. 891-921 Titre : Uncertainty propagation on damage evolution of a concrete structure subjected to coupled leaching and creep Type de document : texte imprimé Auteurs : Thomas de Larrard, Auteur ; Benboudjema, Farid, Auteur ; Jean-Baptiste Colliat, Auteur Année de publication : 2011 Article en page(s) : pp. 891-921 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Leaching Creep Damage Variability Distribution Pearson correlation coefficient Decision tree Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : We introduce a model for calcium leaching and creep strain evolution. Both phenomena are coupled for the estimation of the damage time evolution. Simulations are achieved so as to quantify the influence of the input parameters variability on the structure lifespan. The most influent parameters are identified and threshold values for lifespan classification are enlighted. DEWEY : 624 ISSN : 1964-8189 En ligne : http://ejece.revuesonline.com/resnum.jsp [article] Uncertainty propagation on damage evolution of a concrete structure subjected to coupled leaching and creep [texte imprimé] / Thomas de Larrard, Auteur ; Benboudjema, Farid, Auteur ; Jean-Baptiste Colliat, Auteur . - 2011 . - pp. 891-921. Génie Civil Langues : Anglais (eng) in European journal of environmental and civil engineering > Vol. 14 N° 6-7 (Juin 2010) . - pp. 891-921 Mots-clés : Leaching Creep Damage Variability Distribution Pearson correlation coefficient Decision tree Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : We introduce a model for calcium leaching and creep strain evolution. Both phenomena are coupled for the estimation of the damage time evolution. Simulations are achieved so as to quantify the influence of the input parameters variability on the structure lifespan. The most influent parameters are identified and threshold values for lifespan classification are enlighted. DEWEY : 624 ISSN : 1964-8189 En ligne : http://ejece.revuesonline.com/resnum.jsp

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