Nowadays, construction using natural materials such as earth-based concrete is of major interest for a sustainable society and in response to the challenges of global warming. These materials allow a significant reduction of CO2 and energy consumption in the production process. However, the presence of fine particles in earth concrete makes it sensitive to plastic shrinkage and consequently to cracking risk. Thus, flax fibers have been added to earth concrete to enhance its properties and to prevent the appearance of shrinkage cracking. The effect of adding flax fibers in different percentages (0%, 0.3% and 0.6%) and lengths (12 mm, 24 mm, 50 mm) on fracture properties of earth concrete has been studied. Compressive tests have been conducted on cubic specimens of 10x10x10 cm 3 at 7, 28 and 180 days. Flexural tests have been also realized on prismatic specimens at 28 days. Those tests have been monitored simultaneously with the digital image correlation (DIC) and the acoustic emission (AE) techniques. The results show that the compressive strength, the tensile strength and the AE activity increased with the addition of fibers. Crack displacement fields of hardened concrete and the AE events showed also the development of multi-cracking with the addition of fibers. Those later enhanced the ductility of earth concrete due to fibers bridging of the cracks.
{"title":"Study of the effect of flax fibers on the fracture behavior of earth concrete by simultaneous application of digital image correlation and acoustic emission","authors":"N. Kouta, J. Saliba, Bouchra El Oifi, N. Saiyouri","doi":"10.21012/FC10.235353","DOIUrl":"https://doi.org/10.21012/FC10.235353","url":null,"abstract":"Nowadays, construction using natural materials such as earth-based concrete is of major interest for a sustainable society and in response to the challenges of global warming. These materials allow a significant reduction of CO2 and energy consumption in the production process. However, the presence of fine particles in earth concrete makes it sensitive to plastic shrinkage and consequently to cracking risk. Thus, flax fibers have been added to earth concrete to enhance its properties and to prevent the appearance of shrinkage cracking. The effect of adding flax fibers in different percentages (0%, 0.3% and 0.6%) and lengths (12 mm, 24 mm, 50 mm) on fracture properties of earth concrete has been studied. Compressive tests have been conducted on cubic specimens of 10x10x10 cm 3 at 7, 28 and 180 days. Flexural tests have been also realized on prismatic specimens at 28 days. Those tests have been monitored simultaneously with the digital image correlation (DIC) and the acoustic emission (AE) techniques. The results show that the compressive strength, the tensile strength and the AE activity increased with the addition of fibers. Crack displacement fields of hardened concrete and the AE events showed also the development of multi-cracking with the addition of fibers. Those later enhanced the ductility of earth concrete due to fibers bridging of the cracks.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133136067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Delsaute, R. Furnemont, M. Königsberger, S. Staquet
The foundation of offshore wind turbines in a rocky seabed is a major technical challenge for engineers. To insure the stability of the wind turbine, the ring between the steel monopile and the seabed is filled with a grout. The objective of this research is to point out the influence of early age movements and deformational restraints on the performance of the grouted connections. Another objective is to evaluate the performance of different grout materials by means of several experimental tests. A first experimental campaign is performed to characterize the behavior of the grout during hardening and to define the stress induced by the restraint of the free deformations. In a second campaign, the behavior of the grout under cyclic displacements since casting is studied. A Temperature Stress Testing Machine (TSTM) has been used to simulate the influence of cyclic horizontal movements by applying cyclic displacements and loadings since casting on samples designed with different grout materials. A segregation device was used to simulate the effect of the waves in the vertical direction. The results of both campaigns are then used to evaluate the risk of damage caused by the movement of the waves during the hardening of the grout. From these newly developed experimental tools, new indicators were developed in order to compare the performance of different grouts under cyclic displacement since casting.
{"title":"Influence of cyclic movement on the hardening process of grout: case of offshore wind turbine installation","authors":"B. Delsaute, R. Furnemont, M. Königsberger, S. Staquet","doi":"10.21012/FC10.235333","DOIUrl":"https://doi.org/10.21012/FC10.235333","url":null,"abstract":"The foundation of offshore wind turbines in a rocky seabed is a major technical challenge for engineers. To insure the stability of the wind turbine, the ring between the steel monopile and the seabed is filled with a grout. The objective of this research is to point out the influence of early age movements and deformational restraints on the performance of the grouted connections. Another objective is to evaluate the performance of different grout materials by means of several experimental tests. A first experimental campaign is performed to characterize the behavior of the grout during hardening and to define the stress induced by the restraint of the free deformations. In a second campaign, the behavior of the grout under cyclic displacements since casting is studied. A Temperature Stress Testing Machine (TSTM) has been used to simulate the influence of cyclic horizontal movements by applying cyclic displacements and loadings since casting on samples designed with different grout materials. A segregation device was used to simulate the effect of the waves in the vertical direction. The results of both campaigns are then used to evaluate the risk of damage caused by the movement of the waves during the hardening of the grout. From these newly developed experimental tools, new indicators were developed in order to compare the performance of different grouts under cyclic displacement since casting.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126828884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate the behavior of a two-phase composite consisting of an inclusive elastic phase and an ageing linear viscoelastic matrix (ALVE) experiencing an expansion of the inclusions or equivalently a differential dilation of both phases. We propose, based on an analogy with thermoviscoelasticity, to estimate the macroscopic mechanical properties of the composite and to determine its overall free strains and macroscopic coefficient of expansion. Numerically, 3D cubic specimens are generated with spherical or polyhedral inclusion shapes. Finite element simulations are then performed, allowing to calculate the macroscopic strains generated by the expansions, as well as the moduli at different time of loading. The effect of the inclusions shape on both local and macroscopic behavior are also studied. Analytically, a methodology suitable for estimating the overall behavior of composite materials in an ALVE context is applied, and extended to the case of ageing linear thermoviscoelasticity. Specifically, the macroscopic effects of the expansion of inclusions assumed as spherical are determined via the dilation coefficient, and obtained by a semi-explicit homogenization procedure. Finally, numerical and analytical results are compared in terms of macroscopic response and mechanical properties at different ages, and for various ageing and expansion functions.
{"title":"Numerical and analytical estimation of the ageing linear viscoelastic behavior of a two-phase composite with expansive inclusions","authors":"Tulio Honorio, B. Bary","doi":"10.21012/FC10.235550","DOIUrl":"https://doi.org/10.21012/FC10.235550","url":null,"abstract":"We investigate the behavior of a two-phase composite consisting of an inclusive elastic phase and an ageing linear viscoelastic matrix (ALVE) experiencing an expansion of the inclusions or equivalently a differential dilation of both phases. We propose, based on an analogy with thermoviscoelasticity, to estimate the macroscopic mechanical properties of the composite and to determine its overall free strains and macroscopic coefficient of expansion. Numerically, 3D cubic specimens are generated with spherical or polyhedral inclusion shapes. Finite element simulations are then performed, allowing to calculate the macroscopic strains generated by the expansions, as well as the moduli at different time of loading. The effect of the inclusions shape on both local and macroscopic behavior are also studied. Analytically, a methodology suitable for estimating the overall behavior of composite materials in an ALVE context is applied, and extended to the case of ageing linear thermoviscoelasticity. Specifically, the macroscopic effects of the expansion of inclusions assumed as spherical are determined via the dilation coefficient, and obtained by a semi-explicit homogenization procedure. Finally, numerical and analytical results are compared in terms of macroscopic response and mechanical properties at different ages, and for various ageing and expansion functions.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123447430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
France has today reassessed the safety level of its power plants due to the Fukushima incident. The duration of the cooling system breakdown urged the industry to consider a much longer worst case scenario than was done before. The time frame for the ’severe’ accident subsequently went up from 24h to two weeks. This, in turn, called for an extensive study of creep and vapour transport issues that had previously been left aside. This was the objective of the MACENA project, which aims at evaluating the tightness of a containment vessel under extreme conditions, namely a 5 bar water vapour pressure and 180C temperature during two weeks. Among the scientific issues involved in this problem, the intrinsic permeability of concrete, its relative permeability to vapour and to water and their subsequent evolution upon damage are the subject of this contribution. Our analysis starts from the work of Khaddour et al. on the impact of damage on both intrinsic and apparent permeability with the help of a random hierarchical model based on the pore size distribution of the material. This model yielded good results in terms of the evolution of permeability with damage. Here, we extend this model to the description of multiphase fluid flow. Modifications of the above-mentioned random hierarchical model involve a set of rules that capture the effect of condensation as described by Kelvin’s law. In addition, the capillary assembling process is modified in order to better account for the influence of capillaries of very small diameter, which had no importance on the prediction of the intrinsic permeability but have a strong influence on the relative permeability to vapour. Segments of capillaries of small diameter are redistributed in downstream ends of the bundle according to a probability distribution that has the same shape as the pore size distribution. The extended model is shown to provide rather accurate prediction of relative permeability for a wide range of geomaterials (from mortar to tight and permeable rocks).
{"title":"Predicting the Permeability and Relative Permeability of Concrete","authors":"Lionel Ecay, D. Grégoire, G. Pijaudier-Cabot","doi":"10.21012/FC10.238262","DOIUrl":"https://doi.org/10.21012/FC10.238262","url":null,"abstract":"France has today reassessed the safety level of its power plants due to the Fukushima incident. The duration of the cooling system breakdown urged the industry to consider a much longer worst case scenario than was done before. The time frame for the ’severe’ accident subsequently went up from 24h to two weeks. This, in turn, called for an extensive study of creep and vapour transport issues that had previously been left aside. This was the objective of the MACENA project, which aims at evaluating the tightness of a containment vessel under extreme conditions, namely a 5 bar water vapour pressure and 180C temperature during two weeks. Among the scientific issues involved in this problem, the intrinsic permeability of concrete, its relative permeability to vapour and to water and their subsequent evolution upon damage are the subject of this contribution. Our analysis starts from the work of Khaddour et al. on the impact of damage on both intrinsic and apparent permeability with the help of a random hierarchical model based on the pore size distribution of the material. This model yielded good results in terms of the evolution of permeability with damage. Here, we extend this model to the description of multiphase fluid flow. Modifications of the above-mentioned random hierarchical model involve a set of rules that capture the effect of condensation as described by Kelvin’s law. In addition, the capillary assembling process is modified in order to better account for the influence of capillaries of very small diameter, which had no importance on the prediction of the intrinsic permeability but have a strong influence on the relative permeability to vapour. Segments of capillaries of small diameter are redistributed in downstream ends of the bundle according to a probability distribution that has the same shape as the pore size distribution. The extended model is shown to provide rather accurate prediction of relative permeability for a wide range of geomaterials (from mortar to tight and permeable rocks).","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128747206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The embedding of anchoring systems in the retrofitting of Reinforced Concrete (RC) structures by means of Fiber Reinforced Polymers (FRP) often implies local failure modes associated to high stress concentrations. In order to account for such mechanical behaviours in standard finite element computations, an explicit representation of interfaces is required. This strategy presents, however , several limitations in terms of computational cost and mesh-related issues. On the other hand, implicit models may not be sufficiently accurate in order to reproduce the aforementioned localized phenomena. Specific finite elements for the simulation of pull-out mechanisms are here presented. The presence of interfaces is taken into account by enriching the displacement approximation by means of additional unknowns defined at the element level. Static-condensation, therefore, allows preserving the structure of the finite element procedure and limiting the computational effort.
{"title":"Finite elements with an embedded reinforcement for the simulation of reinforced concrete structures strengthened with FRP","authors":"F. Riccardi, C. Giry, F. Gatuingt","doi":"10.21012/FC10.233539","DOIUrl":"https://doi.org/10.21012/FC10.233539","url":null,"abstract":"The embedding of anchoring systems in the retrofitting of Reinforced Concrete (RC) structures by means of Fiber Reinforced Polymers (FRP) often implies local failure modes associated to high stress concentrations. In order to account for such mechanical behaviours in standard finite element computations, an explicit representation of interfaces is required. This strategy presents, however , several limitations in terms of computational cost and mesh-related issues. On the other hand, implicit models may not be sufficiently accurate in order to reproduce the aforementioned localized phenomena. Specific finite elements for the simulation of pull-out mechanisms are here presented. The presence of interfaces is taken into account by enriching the displacement approximation by means of additional unknowns defined at the element level. Static-condensation, therefore, allows preserving the structure of the finite element procedure and limiting the computational effort.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115169290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analytical solution for fracture analysis of lightly reinforced concrete beams considering bond-slip effect","authors":"Z. Wu","doi":"10.21012/FC10.236339","DOIUrl":"https://doi.org/10.21012/FC10.236339","url":null,"abstract":"","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121084731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the already vast literature dealing with numerical simulations of fracture of concrete elements or structures, a large number of papers deal with cohesive traction-separation laws. However, in many instances, this appears to be a secondary aspect of the published studies, the principal one being the variant of the numerical algorithm being presented in the research. This makes difficult to compare the various available formulations for the vectorial traction-separation law (t–w law). The present work aims at initiating a systematic comparison between the t–w laws, and this is done comparing a subset of the possible formulations using exactly the same numerical algorithms. The analysis is restricted, in this contribution, to damage-based models in the tensile zone (positive normal components of the traction and the crack displacement vectors). All the models use the same uniaxial softening function and the emphasis is on the vectorial character of the t–w law, namely, on the influence of (1) the lack of coaxiality of t and w; (2) the shape of the damage criterion in the traction space; and (3) the influence of the ratio of fracture energies in pure modes I and II. The simulations have been carried out within the finite element framework COFE (Continuum Oriented Finite Element), which implements elements with an embedded adaptable crack to reproduce fracture of concrete as well as a smeared version that, essentially, unifies the numerical algorithms of both approaches.
{"title":"A First Approach to Comparing Cohesive Traction-Separation Laws for Concrete","authors":"J. Planas","doi":"10.21012/FC10.235586","DOIUrl":"https://doi.org/10.21012/FC10.235586","url":null,"abstract":"In the already vast literature dealing with numerical simulations of fracture of concrete elements or structures, a large number of papers deal with cohesive traction-separation laws. However, in many instances, this appears to be a secondary aspect of the published studies, the principal one being the variant of the numerical algorithm being presented in the research. This makes difficult to compare the various available formulations for the vectorial traction-separation law (t–w law). The present work aims at initiating a systematic comparison between the t–w laws, and this is done comparing a subset of the possible formulations using exactly the same numerical algorithms. The analysis is restricted, in this contribution, to damage-based models in the tensile zone (positive normal components of the traction and the crack displacement vectors). All the models use the same uniaxial softening function and the emphasis is on the vectorial character of the t–w law, namely, on the influence of (1) the lack of coaxiality of t and w; (2) the shape of the damage criterion in the traction space; and (3) the influence of the ratio of fracture energies in pure modes I and II. The simulations have been carried out within the finite element framework COFE (Continuum Oriented Finite Element), which implements elements with an embedded adaptable crack to reproduce fracture of concrete as well as a smeared version that, essentially, unifies the numerical algorithms of both approaches.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127098336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A modelling approach is proposed for the simulation of damage in cement pastes at the microscale. The approach takes use of recent advances in hydration modelling tools and the experimental and numerical characterization of micromechanical properties of cement paste phases. It is shown that the modelling approach can illustrate the damage behaviour of the cement matric and predict the properties of well-hydrated cement pastes. It can therefore be used to calculate the macroscopic properties of cement pastes as well as investigate the propagation of damage inside the cement paste matrix without the need for a new identification of model parameters. Some of the limitations to the presented approach are also discussed.
{"title":"Micromechanical characterization of damage in cement pastes: an experimental-numerical study","authors":"A. Rhardane","doi":"10.21012/FC10.235638","DOIUrl":"https://doi.org/10.21012/FC10.235638","url":null,"abstract":"A modelling approach is proposed for the simulation of damage in cement pastes at the microscale. The approach takes use of recent advances in hydration modelling tools and the experimental and numerical characterization of micromechanical properties of cement paste phases. It is shown that the modelling approach can illustrate the damage behaviour of the cement matric and predict the properties of well-hydrated cement pastes. It can therefore be used to calculate the macroscopic properties of cement pastes as well as investigate the propagation of damage inside the cement paste matrix without the need for a new identification of model parameters. Some of the limitations to the presented approach are also discussed.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127283439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the important factors affecting the behaviour of a reinforced concrete (RC) is the bond between concrete and the reinforcement bars. To model the bond between concrete and the reinforcement in the numerical simulation of a RC, accurately modelling for the reinforcing bar with its ribs in 3D shape is required. So to simulate the bond behaviour between concrete and steel rebar, the contact surface between them is represented by normal and shear behaviours. The characteristics of these springs are modified based on numerical simulations to get best-matched results to the experimental results. Therefore, in this study, the opening-sliding relationships between a deformed bar and surrounding matrix are investigated experimentally by using digital images correlation (DIC) technique. A standard axial tension test was applied to a deformed steel bar that was embedded in concrete and cement paste specimen. The specimen had a trapezoidal “window,” which allows full continues observation and measurements of concrete or cement paste displacements by recording high-resolution digital video that was later analysed by DIC software. The half of the steel bar’s cross-section was removed to see directly the ribs of the rebar and thereby capture the local deformations between these ribs. For that purpose 15 points were chosen, at the tips of the ribs and also between the ribs of the deformed bar, to investigate the relative displacements between the deformed bar and surrounding matrix in X-direction and Y-direction. Based on the results of the experiments, some relationships between opening and sliding in case of cement paste or concrete were established. It was found that the opening between the concrete and the rebar at the tip of the rib is higher than between the ribs. Also, the sliding between the concrete and the rebar at the tip of the rib is higher than between the ribs. A. Okeil, R. Upadhyay, K. Matsumoto and K. Nagai
影响钢筋混凝土(RC)性能的重要因素之一是混凝土与钢筋之间的粘结。在钢筋混凝土数值模拟中，为了模拟混凝土与钢筋之间的粘结关系，需要对钢筋进行精确的三维建模。因此，为了模拟混凝土与钢筋之间的粘结行为，混凝土与钢筋之间的接触面用法向和剪切特性来表示。在数值模拟的基础上对弹簧的特性进行了修正，得到了与实验结果最匹配的结果。因此，本研究采用数字图像相关(DIC)技术对变形杆与周围基体之间的开滑关系进行了实验研究。采用标准轴向拉伸试验方法，将变形钢筋嵌入混凝土和水泥膏体试件中。该标本有一个梯形“窗口”，通过记录高分辨率数字视频，可以对混凝土或水泥膏体的位移进行完整的连续观察和测量，这些视频随后由DIC软件进行分析。钢筋横截面的一半被移除，以直接看到钢筋的肋骨，从而捕捉到这些肋骨之间的局部变形。为此，在肋的尖端和变形杆的肋之间选择了15个点来研究变形杆与周围矩阵在x方向和y方向上的相对位移。在试验的基础上，建立了水泥浆体或混凝土情况下开口与滑动的关系。结果表明，肋尖处混凝土与钢筋之间的开口大于肋间开口。此外，肋尖处混凝土与钢筋之间的滑动比肋间的滑动要大。A. Okeil, R. Upadhyay, K. Matsumoto和K. Nagai
{"title":"Investigation of local opening-sliding relationship in the vicinity of deformed bar in concrete by using DIC technique","authors":"A. Okeil","doi":"10.21012/FC10.232788","DOIUrl":"https://doi.org/10.21012/FC10.232788","url":null,"abstract":"One of the important factors affecting the behaviour of a reinforced concrete (RC) is the bond between concrete and the reinforcement bars. To model the bond between concrete and the reinforcement in the numerical simulation of a RC, accurately modelling for the reinforcing bar with its ribs in 3D shape is required. So to simulate the bond behaviour between concrete and steel rebar, the contact surface between them is represented by normal and shear behaviours. The characteristics of these springs are modified based on numerical simulations to get best-matched results to the experimental results. Therefore, in this study, the opening-sliding relationships between a deformed bar and surrounding matrix are investigated experimentally by using digital images correlation (DIC) technique. A standard axial tension test was applied to a deformed steel bar that was embedded in concrete and cement paste specimen. The specimen had a trapezoidal “window,” which allows full continues observation and measurements of concrete or cement paste displacements by recording high-resolution digital video that was later analysed by DIC software. The half of the steel bar’s cross-section was removed to see directly the ribs of the rebar and thereby capture the local deformations between these ribs. For that purpose 15 points were chosen, at the tips of the ribs and also between the ribs of the deformed bar, to investigate the relative displacements between the deformed bar and surrounding matrix in X-direction and Y-direction. Based on the results of the experiments, some relationships between opening and sliding in case of cement paste or concrete were established. It was found that the opening between the concrete and the rebar at the tip of the rib is higher than between the ribs. Also, the sliding between the concrete and the rebar at the tip of the rib is higher than between the ribs. A. Okeil, R. Upadhyay, K. Matsumoto and K. Nagai","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129503175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Finite element analysis of hygro-thermal behaviour of concrete during controlled fire spalling","authors":"R. Baydoun","doi":"10.21012/FC10.233231","DOIUrl":"https://doi.org/10.21012/FC10.233231","url":null,"abstract":"","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129693728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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