afif rahma - Academia.edu (original) (raw)
Papers by afif rahma
Currently, the design of the concrete mix is an important part of the environmental problem. In f... more Currently, the design of the concrete mix is an important part of the environmental problem. In front of this question, engineers face a major challenge that is addressed in two ways. On one hand, how do they use its component materials to improve its mechanical properties, on the other hand how do they use less polluting materials? Hence, in an environmental and economical view, laboratory tests were carried out on samples of concrete reinforced with smooth steel fiber extracted from the waste tires, in order to assess its impact and to prove its mechanical feasibility for these purposes. Consequently, laboratory results have shown satisfactory improvement in the behavior of concrete under compression loads in the elastic stage and an increase in ductility and toughness of the matrix in the plastic stage. Besides, taking into account the discontinuity and the structural disturbances observed during the loading of samples in the post-elastic state, a method has been proposed to calc...
European Journal of Mechanics A-solids, 1994
A methodology for connecting the parameters of a discontinuous and a fictitious continuous medium... more A methodology for connecting the parameters of a discontinuous and a fictitious continuous medium has been developed and applied to granular materials, which enable us to explain the main correlations that exist between parameters of classic models for continuous media (elasticity, plasticity...) and physical parmaters of the grains. This method was then extended to an elastoplastic model called the Cyclade model originally developed for soils. Correlations between nature and compacity parameters of grain assemblies and parameters of the constitutive model representing the mechanical behaviour of the fictitious continiuous medium have been proposed and validated for sands
ةلئسأ حرط ةساردلا لواحت قرطلا هذه ضرع للاخ نمو ،بلاطلا تاجرد ميوقتل ةحرتقملا ةيضايرلا قرطلل ةيدقن... more ةلئسأ حرط ةساردلا لواحت قرطلا هذه ضرع للاخ نمو ،بلاطلا تاجرد ميوقتل ةحرتقملا ةيضايرلا قرطلل ةيدقن ةعجارم ثحبلا اذه مدقي امك .قرطلا هذه قيبطت دودحو ،تارابتخلاا تاجرد ميوقت قرط اهيلع موقت يتلا سسلأاو ريياعملاو ،تارابتخلاا جئاتن يف تتشتلا بابسأ :لثم ةسيئر يف ليجستلاو لوبقلا طورشو ،ميلعتلاو ملعتلا ةيلمعب ةصاخلاو ةيتاذلا لماوعلاو ،بلاطلل يفرعملا ىوتسملا رود يف رظنلا اًضيأ ةساردلا لواحت ؟ميلعتلا تاجرخمو تارابتخلاا جئاتن ىلع قبس ام رثأو ،ةيساردلا جماربلا
Cogent Social Sciences, 2019
On a daily basis, individuals are exposed to potential poisoning by different sources such as med... more On a daily basis, individuals are exposed to potential poisoning by different sources such as medicines, food, alcohol, pesticides, and chemical cleaning materials. In these circumstances, individuals often need to undergo medical emergency interventions to manage the serious consequences that can appear simultaneously with the poisoning or in the long term.
Cogent Engineering, 2018
as soon as possible after acceptance. Copyediting, typesetting, and review of the resulting proof... more as soon as possible after acceptance. Copyediting, typesetting, and review of the resulting proof will be undertaken on this manuscript before final publication of the Version of Record (VoR). Please note that during production and pre-press, errors may be discovered which could affect the content.
Cogent Engineering, 2017
Several studies have been made to examine the potential mineralogical and mechanical properties o... more Several studies have been made to examine the potential mineralogical and mechanical properties of glass aiming to improve the characteristic properties of concrete where glass has been used in various forms, powder form or fine and coarse aggregate form, taken as part of aggregate or replacement of cement. However, the results presented in these studies were sometimes very different, even contradictory, due to the way in which the glass was used in these experiments, leading to a difficulty in distinguishing between the effect of Glass and the role of cement. To overcome this confusion the present research aimed to study the effects of glass powder on the properties of concrete by series of test for two constant quantities of cement, 350 and 400 kg per cubic meter. To reach the target of this research, two campaigns were done. In the first campaign the glass powder is gradually increased from trial to another by an increment of 2.5% of the cement's weight, from a rate of 2.5 up to 15%, without any chemical additive. This methodology made it possible to show the effect of the glass powder on the characteristic properties of concrete and defined its real contribution without being confused with the role of the cement. In the second campaign the study is extended to add the
European Journal of Mechanics - A/Solids, 2001
Granular materials are constituted of an assembly of particles. In spite of the simplicity of thi... more Granular materials are constituted of an assembly of particles. In spite of the simplicity of this assembly, its mechanical behaviour is complex. In the first stage we propose a framework to establish correlations between parameters of the supposedly continuous medium and grain properties which are assumed to be constant. However, this hypothesis is no longer valid in the case where physical (shape, size...) or mechanical properties (Young modulus E g , Poisson's ratio ν g ...) of grains evolve during loading, causing the behaviour of the assembly to modify. We study the influence of the physical and mechanical parameters on grain breakage. We subsequently propose a way to model the influence of the grain breakage on granular materials and we introduce this influence in an elastoplastic constitutive model. Validations are made on two kinds of sands under isotropic and triaxial loading. Since the results of numerical computations corresponded well with the experimental data, we believe that the new model is capable of accurately simulating the behaviour of granular materials under a wide range of stresses and of taking into account, through new parameters, the individual strength of grains. elastoplastic model / grain breakage / high pressure
Canadian Geotechnical Journal, 1998
The influence of grain crushing under high stress levels is introduced in the elasto-plastic cons... more The influence of grain crushing under high stress levels is introduced in the elasto-plastic constitutive law (Hujeux's model) using additional variables that change with the physical and mechanical properties of the grains. These variables are defined as functions of the amount of dissipated plastic work, which is proposed as a parameter for describing the material yield. The results of computer simulations along oedometric and triaxial paths indicate a very good agreement between the experimental curves and the numerical solutions. The proposed modifications are therefore validated.Key words: correlation, grain crushing, constitutive law, modelization, plastic work.[Journal translation]
Probabilities and Materials, 1994
For the soils, the micro structure is given at the scale of the grains whose the characteristics ... more For the soils, the micro structure is given at the scale of the grains whose the characteristics are the micro structure parameters. To predict the macro structure parameters of the soils, it is necessary to have a good and plentiful description of the micro structure. Unfortunately, the data which are available about the grains, in soils mechanics, do not describe the grain but the assembly of the grains and are called physical or identification parameters. To make the best use of these informations we have to find the micro structural mechanical meaning of the parameters and the logic of connection between them and the macro structural mechanical parameters.
Le theme centrale de ce travail est de montrer la faisabilite d'une demarche existant a reche... more Le theme centrale de ce travail est de montrer la faisabilite d'une demarche existant a rechercher les liens existant entre des parametres d'identification de nature physique et mecanique (granulometrie, Emin et Emax) (parametres du milieu discontinu) a des parametres utilises dans des modeles de comportement (cyclade) (parametres du milieu continu). Son interet premier reside dans la necessite, pour des modeles sophistiques necessitant un nombre de parametres assez eleve, de pouvoir partir d'un jeu initial suffisamment realiste pour pouvoir mettre en œuvre une optimisation a partir de resultats experimentaux. Un deuxieme interet est de pouvoir predire le comportement des sols qu'il n'est pas possible de prelever intacts et qui ne peuvent pas faire l'objet d'une campagne d'essais de laboratoires classiques. Des methodes statistiques et d'analyse de donnees, ont ete utilisees a la construction des modeles de correlations entre parametres du milieu ...
Currently, the design of the concrete mix is an important part of the environmental problem. In f... more Currently, the design of the concrete mix is an important part of the environmental problem. In front of this question, engineers face a major challenge that is addressed in two ways. On one hand, how do they use its component materials to improve its mechanical properties, on the other hand how do they use less polluting materials? Hence, in an environmental and economical view, laboratory tests were carried out on samples of concrete reinforced with smooth steel fiber extracted from the waste tires, in order to assess its impact and to prove its mechanical feasibility for these purposes. Consequently, laboratory results have shown satisfactory improvement in the behavior of concrete under compression loads in the elastic stage and an increase in ductility and toughness of the matrix in the plastic stage. Besides, taking into account the discontinuity and the structural disturbances observed during the loading of samples in the post-elastic state, a method has been proposed to calc...
European Journal of Mechanics A-solids, 1994
A methodology for connecting the parameters of a discontinuous and a fictitious continuous medium... more A methodology for connecting the parameters of a discontinuous and a fictitious continuous medium has been developed and applied to granular materials, which enable us to explain the main correlations that exist between parameters of classic models for continuous media (elasticity, plasticity...) and physical parmaters of the grains. This method was then extended to an elastoplastic model called the Cyclade model originally developed for soils. Correlations between nature and compacity parameters of grain assemblies and parameters of the constitutive model representing the mechanical behaviour of the fictitious continiuous medium have been proposed and validated for sands
ةلئسأ حرط ةساردلا لواحت قرطلا هذه ضرع للاخ نمو ،بلاطلا تاجرد ميوقتل ةحرتقملا ةيضايرلا قرطلل ةيدقن... more ةلئسأ حرط ةساردلا لواحت قرطلا هذه ضرع للاخ نمو ،بلاطلا تاجرد ميوقتل ةحرتقملا ةيضايرلا قرطلل ةيدقن ةعجارم ثحبلا اذه مدقي امك .قرطلا هذه قيبطت دودحو ،تارابتخلاا تاجرد ميوقت قرط اهيلع موقت يتلا سسلأاو ريياعملاو ،تارابتخلاا جئاتن يف تتشتلا بابسأ :لثم ةسيئر يف ليجستلاو لوبقلا طورشو ،ميلعتلاو ملعتلا ةيلمعب ةصاخلاو ةيتاذلا لماوعلاو ،بلاطلل يفرعملا ىوتسملا رود يف رظنلا اًضيأ ةساردلا لواحت ؟ميلعتلا تاجرخمو تارابتخلاا جئاتن ىلع قبس ام رثأو ،ةيساردلا جماربلا
Cogent Social Sciences, 2019
On a daily basis, individuals are exposed to potential poisoning by different sources such as med... more On a daily basis, individuals are exposed to potential poisoning by different sources such as medicines, food, alcohol, pesticides, and chemical cleaning materials. In these circumstances, individuals often need to undergo medical emergency interventions to manage the serious consequences that can appear simultaneously with the poisoning or in the long term.
Cogent Engineering, 2018
as soon as possible after acceptance. Copyediting, typesetting, and review of the resulting proof... more as soon as possible after acceptance. Copyediting, typesetting, and review of the resulting proof will be undertaken on this manuscript before final publication of the Version of Record (VoR). Please note that during production and pre-press, errors may be discovered which could affect the content.
Cogent Engineering, 2017
Several studies have been made to examine the potential mineralogical and mechanical properties o... more Several studies have been made to examine the potential mineralogical and mechanical properties of glass aiming to improve the characteristic properties of concrete where glass has been used in various forms, powder form or fine and coarse aggregate form, taken as part of aggregate or replacement of cement. However, the results presented in these studies were sometimes very different, even contradictory, due to the way in which the glass was used in these experiments, leading to a difficulty in distinguishing between the effect of Glass and the role of cement. To overcome this confusion the present research aimed to study the effects of glass powder on the properties of concrete by series of test for two constant quantities of cement, 350 and 400 kg per cubic meter. To reach the target of this research, two campaigns were done. In the first campaign the glass powder is gradually increased from trial to another by an increment of 2.5% of the cement's weight, from a rate of 2.5 up to 15%, without any chemical additive. This methodology made it possible to show the effect of the glass powder on the characteristic properties of concrete and defined its real contribution without being confused with the role of the cement. In the second campaign the study is extended to add the
European Journal of Mechanics - A/Solids, 2001
Granular materials are constituted of an assembly of particles. In spite of the simplicity of thi... more Granular materials are constituted of an assembly of particles. In spite of the simplicity of this assembly, its mechanical behaviour is complex. In the first stage we propose a framework to establish correlations between parameters of the supposedly continuous medium and grain properties which are assumed to be constant. However, this hypothesis is no longer valid in the case where physical (shape, size...) or mechanical properties (Young modulus E g , Poisson's ratio ν g ...) of grains evolve during loading, causing the behaviour of the assembly to modify. We study the influence of the physical and mechanical parameters on grain breakage. We subsequently propose a way to model the influence of the grain breakage on granular materials and we introduce this influence in an elastoplastic constitutive model. Validations are made on two kinds of sands under isotropic and triaxial loading. Since the results of numerical computations corresponded well with the experimental data, we believe that the new model is capable of accurately simulating the behaviour of granular materials under a wide range of stresses and of taking into account, through new parameters, the individual strength of grains. elastoplastic model / grain breakage / high pressure
Canadian Geotechnical Journal, 1998
The influence of grain crushing under high stress levels is introduced in the elasto-plastic cons... more The influence of grain crushing under high stress levels is introduced in the elasto-plastic constitutive law (Hujeux's model) using additional variables that change with the physical and mechanical properties of the grains. These variables are defined as functions of the amount of dissipated plastic work, which is proposed as a parameter for describing the material yield. The results of computer simulations along oedometric and triaxial paths indicate a very good agreement between the experimental curves and the numerical solutions. The proposed modifications are therefore validated.Key words: correlation, grain crushing, constitutive law, modelization, plastic work.[Journal translation]
Probabilities and Materials, 1994
For the soils, the micro structure is given at the scale of the grains whose the characteristics ... more For the soils, the micro structure is given at the scale of the grains whose the characteristics are the micro structure parameters. To predict the macro structure parameters of the soils, it is necessary to have a good and plentiful description of the micro structure. Unfortunately, the data which are available about the grains, in soils mechanics, do not describe the grain but the assembly of the grains and are called physical or identification parameters. To make the best use of these informations we have to find the micro structural mechanical meaning of the parameters and the logic of connection between them and the macro structural mechanical parameters.
Le theme centrale de ce travail est de montrer la faisabilite d'une demarche existant a reche... more Le theme centrale de ce travail est de montrer la faisabilite d'une demarche existant a rechercher les liens existant entre des parametres d'identification de nature physique et mecanique (granulometrie, Emin et Emax) (parametres du milieu discontinu) a des parametres utilises dans des modeles de comportement (cyclade) (parametres du milieu continu). Son interet premier reside dans la necessite, pour des modeles sophistiques necessitant un nombre de parametres assez eleve, de pouvoir partir d'un jeu initial suffisamment realiste pour pouvoir mettre en œuvre une optimisation a partir de resultats experimentaux. Un deuxieme interet est de pouvoir predire le comportement des sols qu'il n'est pas possible de prelever intacts et qui ne peuvent pas faire l'objet d'une campagne d'essais de laboratoires classiques. Des methodes statistiques et d'analyse de donnees, ont ete utilisees a la construction des modeles de correlations entre parametres du milieu ...