Christophe Lanos - Academia.edu (original) (raw)
Papers by Christophe Lanos
Bio-aggregates Based Building Materials
This chapter reports the state of the art of several investigations on behaviour of bio-aggregate... more This chapter reports the state of the art of several investigations on behaviour of bio-aggregate based building materials exposed to fire. Discrepancies between fire reaction and fire resistance is highlighted in this chapter. Various results of fire reaction test performed on bio based materials are presented. Bio-aggregates are often in Class F while concretes range in class B1. In the case of fire performances, limited tests are performed and reported in the literature. Such test must be performed on wall or part of building to give the more realistic overview of the behaviour of building structure exposed to standard fire. In some of presented case studies, render and plaster play a key role in the fire resistance. EI 90 fire resistance appeared to be accessible with conventional technologies.
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In the frame of Isobio project, several multi-layers solutions were developed to be used as typic... more In the frame of Isobio project, several multi-layers solutions were developed to be used as typical wall for new building. The proposed solution wall is made of a wood frame and a commercial oriented strand board (OSB) filled with flexible insulation panel (hemp-flax-cotton panel). Rigid insulation panels placed on each faces (compressed straw board and rigid hemp panel) support a lime based external render and a clay-based plaster. Alternatives solutions are derived from the referent solution. The fire resistance of three building solutions is evaluated at a representative scale using ISO 834 fire curve. Four test configurations are tested placing thermocouples at each interface of the multilayer wall to record the heating kinetic. Smoke resistance, cracks and color changes are quoted during the test. The analysis of specimens degradation during fire test is full of interest to understand the fire behavior of such type of bio-based materials and to confirm the design of the propose...
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Eur J Environ Civ Eng, 2009
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Http Www Theses Fr, 1993
Les travaux presentes proposent une methode d'identification du comportement d'un fluide ... more Les travaux presentes proposent une methode d'identification du comportement d'un fluide reposant sur l'analyse des evolutions de la dissipation d'energie en fonction de la geometrie de l'ecoulement. Cette analyse revele que certains ecoulements font apparaitre, pour des fluides dont le comportement est compose, l'enregistrement de l'evolution du taux de dissipation d'energie comme etant la superposition des evolutions caracteristiques de chaque composante. La connaissance d'un ensemble suffisant d'evolutions caracteristiques permet donc de proposer une identification d'un comportement, basee sur la recherche d'une decomposition de celui-ci en comportements elementaires connus. Ce principe d'identification est applique au test du plastometre a plateaux paralleles (non rotatifs). Dans un premier temps nous considerons que cet ecoulement respecte le principe de superposition enonce precedemment. Une discussion relative a l'aptitude des resultats du plastometre a caracteriser un comportement debouche sur la proposition d'une methodologie d'exploitation de ce test. Via quelques adaptations geometriques de l'essai, la methode s'applique egalement a des fluides frottants. Pour ce test une bibliotheque d'identification est creee. Elle fournit, de facon analytique, les evolutions des taux de dissipation de certains comportements classiques. L'exemple de la solution bâtie pour l'ecoulement d'un fluide viscoplastique permet de confirmer notre principe d'identification. L'ecoulement au plastometre ne respectant pas parfaitement le principe de superposition, une estimation plus precise des valeurs des parametres du comportement compose identifie peut etre obtenue au moyen d'un processus iteratif. L'exemple d'un fluide viscoplastique image ce processus. Un ensemble d'essais realises sur des produits pouvant presenter des seuils de plasticite ou des comportements frottants aux parois permet de verifier experimentalement diverses constatations faites lors de la construction analytique de la bibliotheque. Par ailleurs les resultats obtenus au plastometre sont compares a ceux obtenus par d'autres tests rheometriques. Ces essais accreditent notre methode, et soulignent particulierement l'interet de l'usage du plastometre pour la caracterisation des fluides a seuil
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AIP Conference Proceedings, 2008
A lot of materials have a solid or a liquid behaviour, depending on the value of the stress level... more A lot of materials have a solid or a liquid behaviour, depending on the value of the stress level. This paper is devoted to the proposition of a fundamental constitutive model, for the understanding of such transition. The model is based on a scalar internal variable, which characterizes the shear microcracking, leading to the fluid constitutive behaviour when the material is sufficiently damaged.
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AIP Conference Proceedings, 2008
A systematic study of squeeze flow (SF) is presented using different concentrations of carbopol w... more A systematic study of squeeze flow (SF) is presented using different concentrations of carbopol with varying yield stresses. A constant volume of sample is placed between two parallel plates and a series of 3 constant force steps applied; each lasting 8 minutes, allowing the sample to achieve a limiting height before the next force is applied. The yield stress of each fluid can be calculated from the limiting height as predicted by SF theory. In this study, the reliability of SF for the determination of the yield stress is analyzed through comparison with precise rheometrical tests. The rheometrical data is combined with SF theory to obtain the predicted dynamic height evolution. The predicted height evolution represents the results of the SF experiments quite nicely. Ultimately, the yield stress values determined from the SF experiments and those of the precise rheometrical tests are in good agreement.
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Hellesland/Reinforced Concrete Beams, Columns and Frames, 2013
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Hellesland/Reinforced Concrete Beams, Columns and Frames, 2013
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International Journal of Damage Mechanics, 2008
In this article, a family of damage models which leads to the analytical solvability of the nonlo... more In this article, a family of damage models which leads to the analytical solvability of the nonlocal evolution problem of a homogeneous bar in tension is defined. Explicit gradient damage models and implicit gradient damage models are investigated in a simple structural framework. The natural boundary conditions are derived from a variational principle, and are obtained at the boundary of the damage zone. It is shown that these damage models are the only ones leading to a linear differential equation of the strain variable. Some closed-form solutions are then available, providing a useful framework for the verification of computational models. Furthermore, these continuum damage mechanics models are well suited for the tension behavior of quasi-brittle materials, such as rock or concrete materials. It is theoretically shown that the damage zone evolves with the load level. This dependence of the localization zone to the loading parameter, is a basic feature, which is generally well accepted, from an experimental point of view. The strain profiles are also theoretically obtained, and corroborate well with what is usually numerically found for such nonlocal models. An imperfection analysis shows that the softening evolution problem is well posed in presence of strength imperfections. However, explicit gradient damage models lead to physically questionable results, in presence of imperfections. It is then recommended to use implicit gradient damage models when modeling realistic structures. It is hoped that the present article could serve as a benchmark to numerical gradient-damage finite element codes.
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Materials and Structures, 2014
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Casandjian/Reinforced Concrete Beams, Columns and Frames, 2013
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Casandjian/Reinforced Concrete Beams, Columns and Frames, 2013
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Casandjian/Reinforced Concrete Beams, Columns and Frames, 2013
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Hellesland/Reinforced Concrete Beams, Columns and Frames, 2013
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Rheologica Acta, 2009
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Journal of Vibration and Control, 2009
This paper is devoted to the dynamic analysis of two connected beam columns with a variation of t... more This paper is devoted to the dynamic analysis of two connected beam columns with a variation of the bending connection and minor perturbations of the length of each span. The point of reduced bending stiffness represented by a rotational spring may result from a crack. This rotational spring can also be associated with a semi-rigid connection in the field of steel or composite structures, for instance. The dynamics of this axially loaded two-span weakened column appears to exhibit strong localization for small values of stiffness of the rotational spring. The vibration mode shapes indicate a strong confinement of the vibration level to a fraction of the column. A quantitative criterion of localization is established and is correlated to well-known phenomena such as curve veering effect or close eigenvalues. Such a result is quite encouraging as localization is strongly associated with the flexibility values of the rotational spring. When considering the open crack analogy, localizat...
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Bio-aggregates Based Building Materials
This chapter reports the state of the art of several investigations on behaviour of bio-aggregate... more This chapter reports the state of the art of several investigations on behaviour of bio-aggregate based building materials exposed to fire. Discrepancies between fire reaction and fire resistance is highlighted in this chapter. Various results of fire reaction test performed on bio based materials are presented. Bio-aggregates are often in Class F while concretes range in class B1. In the case of fire performances, limited tests are performed and reported in the literature. Such test must be performed on wall or part of building to give the more realistic overview of the behaviour of building structure exposed to standard fire. In some of presented case studies, render and plaster play a key role in the fire resistance. EI 90 fire resistance appeared to be accessible with conventional technologies.
Bookmarks Related papers MentionsView impact
In the frame of Isobio project, several multi-layers solutions were developed to be used as typic... more In the frame of Isobio project, several multi-layers solutions were developed to be used as typical wall for new building. The proposed solution wall is made of a wood frame and a commercial oriented strand board (OSB) filled with flexible insulation panel (hemp-flax-cotton panel). Rigid insulation panels placed on each faces (compressed straw board and rigid hemp panel) support a lime based external render and a clay-based plaster. Alternatives solutions are derived from the referent solution. The fire resistance of three building solutions is evaluated at a representative scale using ISO 834 fire curve. Four test configurations are tested placing thermocouples at each interface of the multilayer wall to record the heating kinetic. Smoke resistance, cracks and color changes are quoted during the test. The analysis of specimens degradation during fire test is full of interest to understand the fire behavior of such type of bio-based materials and to confirm the design of the propose...
Bookmarks Related papers MentionsView impact
Eur J Environ Civ Eng, 2009
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Http Www Theses Fr, 1993
Les travaux presentes proposent une methode d'identification du comportement d'un fluide ... more Les travaux presentes proposent une methode d'identification du comportement d'un fluide reposant sur l'analyse des evolutions de la dissipation d'energie en fonction de la geometrie de l'ecoulement. Cette analyse revele que certains ecoulements font apparaitre, pour des fluides dont le comportement est compose, l'enregistrement de l'evolution du taux de dissipation d'energie comme etant la superposition des evolutions caracteristiques de chaque composante. La connaissance d'un ensemble suffisant d'evolutions caracteristiques permet donc de proposer une identification d'un comportement, basee sur la recherche d'une decomposition de celui-ci en comportements elementaires connus. Ce principe d'identification est applique au test du plastometre a plateaux paralleles (non rotatifs). Dans un premier temps nous considerons que cet ecoulement respecte le principe de superposition enonce precedemment. Une discussion relative a l'aptitude des resultats du plastometre a caracteriser un comportement debouche sur la proposition d'une methodologie d'exploitation de ce test. Via quelques adaptations geometriques de l'essai, la methode s'applique egalement a des fluides frottants. Pour ce test une bibliotheque d'identification est creee. Elle fournit, de facon analytique, les evolutions des taux de dissipation de certains comportements classiques. L'exemple de la solution bâtie pour l'ecoulement d'un fluide viscoplastique permet de confirmer notre principe d'identification. L'ecoulement au plastometre ne respectant pas parfaitement le principe de superposition, une estimation plus precise des valeurs des parametres du comportement compose identifie peut etre obtenue au moyen d'un processus iteratif. L'exemple d'un fluide viscoplastique image ce processus. Un ensemble d'essais realises sur des produits pouvant presenter des seuils de plasticite ou des comportements frottants aux parois permet de verifier experimentalement diverses constatations faites lors de la construction analytique de la bibliotheque. Par ailleurs les resultats obtenus au plastometre sont compares a ceux obtenus par d'autres tests rheometriques. Ces essais accreditent notre methode, et soulignent particulierement l'interet de l'usage du plastometre pour la caracterisation des fluides a seuil
Bookmarks Related papers MentionsView impact
AIP Conference Proceedings, 2008
A lot of materials have a solid or a liquid behaviour, depending on the value of the stress level... more A lot of materials have a solid or a liquid behaviour, depending on the value of the stress level. This paper is devoted to the proposition of a fundamental constitutive model, for the understanding of such transition. The model is based on a scalar internal variable, which characterizes the shear microcracking, leading to the fluid constitutive behaviour when the material is sufficiently damaged.
Bookmarks Related papers MentionsView impact
AIP Conference Proceedings, 2008
A systematic study of squeeze flow (SF) is presented using different concentrations of carbopol w... more A systematic study of squeeze flow (SF) is presented using different concentrations of carbopol with varying yield stresses. A constant volume of sample is placed between two parallel plates and a series of 3 constant force steps applied; each lasting 8 minutes, allowing the sample to achieve a limiting height before the next force is applied. The yield stress of each fluid can be calculated from the limiting height as predicted by SF theory. In this study, the reliability of SF for the determination of the yield stress is analyzed through comparison with precise rheometrical tests. The rheometrical data is combined with SF theory to obtain the predicted dynamic height evolution. The predicted height evolution represents the results of the SF experiments quite nicely. Ultimately, the yield stress values determined from the SF experiments and those of the precise rheometrical tests are in good agreement.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Hellesland/Reinforced Concrete Beams, Columns and Frames, 2013
Bookmarks Related papers MentionsView impact
Hellesland/Reinforced Concrete Beams, Columns and Frames, 2013
Bookmarks Related papers MentionsView impact
International Journal of Damage Mechanics, 2008
In this article, a family of damage models which leads to the analytical solvability of the nonlo... more In this article, a family of damage models which leads to the analytical solvability of the nonlocal evolution problem of a homogeneous bar in tension is defined. Explicit gradient damage models and implicit gradient damage models are investigated in a simple structural framework. The natural boundary conditions are derived from a variational principle, and are obtained at the boundary of the damage zone. It is shown that these damage models are the only ones leading to a linear differential equation of the strain variable. Some closed-form solutions are then available, providing a useful framework for the verification of computational models. Furthermore, these continuum damage mechanics models are well suited for the tension behavior of quasi-brittle materials, such as rock or concrete materials. It is theoretically shown that the damage zone evolves with the load level. This dependence of the localization zone to the loading parameter, is a basic feature, which is generally well accepted, from an experimental point of view. The strain profiles are also theoretically obtained, and corroborate well with what is usually numerically found for such nonlocal models. An imperfection analysis shows that the softening evolution problem is well posed in presence of strength imperfections. However, explicit gradient damage models lead to physically questionable results, in presence of imperfections. It is then recommended to use implicit gradient damage models when modeling realistic structures. It is hoped that the present article could serve as a benchmark to numerical gradient-damage finite element codes.
Bookmarks Related papers MentionsView impact
Materials and Structures, 2014
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Casandjian/Reinforced Concrete Beams, Columns and Frames, 2013
Bookmarks Related papers MentionsView impact
Casandjian/Reinforced Concrete Beams, Columns and Frames, 2013
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Casandjian/Reinforced Concrete Beams, Columns and Frames, 2013
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Hellesland/Reinforced Concrete Beams, Columns and Frames, 2013
Bookmarks Related papers MentionsView impact
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Rheologica Acta, 2009
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Journal of Vibration and Control, 2009
This paper is devoted to the dynamic analysis of two connected beam columns with a variation of t... more This paper is devoted to the dynamic analysis of two connected beam columns with a variation of the bending connection and minor perturbations of the length of each span. The point of reduced bending stiffness represented by a rotational spring may result from a crack. This rotational spring can also be associated with a semi-rigid connection in the field of steel or composite structures, for instance. The dynamics of this axially loaded two-span weakened column appears to exhibit strong localization for small values of stiffness of the rotational spring. The vibration mode shapes indicate a strong confinement of the vibration level to a fraction of the column. A quantitative criterion of localization is established and is correlated to well-known phenomena such as curve veering effect or close eigenvalues. Such a result is quite encouraging as localization is strongly associated with the flexibility values of the rotational spring. When considering the open crack analogy, localizat...
Bookmarks Related papers MentionsView impact