Loss of bond between steel and concrete is one of the effects of corrosion of reinforced concrete specimens. In order to study that, push-out tests were designed and carried out in previous works, in which the specimens were slices cut from concrete prisms reinforced with a smooth steel tube. This allows adhesion and friction to be investigated, avoiding influence of bar deformations on bond stress. The prisms were subjected to accelerated corrosion tests within the framework of a general study of cracking of concrete due to reinforcement corrosion, as presented in previous conferences. In this work simulation of the bond tests has been carried out in order to study numerically the effect of adherence and friction, by using three-dimensional models of the specimens. 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 according to the standard cohesive model. Additionally, joint elements with cohesive softening and friction have been programmed to reproduce the behavior of the steel-concrete interface. The numerical and experimental results of specimens not subjected to accelerated corrosion show a good agreement, which confirms that a cohesive-frictional law is adequate to reproduce the interface behavior. In addition, the effect of adhesion and friction on bond has been studied separately in the simulations. In the paper, the main aspects of the push-out tests are introduced, formulation of the joint elements is presented, and the numerical and experimental results are analyzed, with special focus on the numerical aspects of the constitutive law of the joint elements.
{"title":"Simulation of push-out tests of corroded reinforced concrete specimens by means of cohesive interface elements with frictional behavior","authors":"B. Sanz","doi":"10.21012/FC10.235566","DOIUrl":"https://doi.org/10.21012/FC10.235566","url":null,"abstract":"Loss of bond between steel and concrete is one of the effects of corrosion of reinforced concrete specimens. In order to study that, push-out tests were designed and carried out in previous works, in which the specimens were slices cut from concrete prisms reinforced with a smooth steel tube. This allows adhesion and friction to be investigated, avoiding influence of bar deformations on bond stress. The prisms were subjected to accelerated corrosion tests within the framework of a general study of cracking of concrete due to reinforcement corrosion, as presented in previous conferences. In this work simulation of the bond tests has been carried out in order to study numerically the effect of adherence and friction, by using three-dimensional models of the specimens. 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 according to the standard cohesive model. Additionally, joint elements with cohesive softening and friction have been programmed to reproduce the behavior of the steel-concrete interface. The numerical and experimental results of specimens not subjected to accelerated corrosion show a good agreement, which confirms that a cohesive-frictional law is adequate to reproduce the interface behavior. In addition, the effect of adhesion and friction on bond has been studied separately in the simulations. In the paper, the main aspects of the push-out tests are introduced, formulation of the joint elements is presented, and the numerical and experimental results are analyzed, with special focus on the numerical aspects of the constitutive law of the joint elements.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"40 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":"128060825","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}
This work studies the influence of fiber content and loading rate on the mixed-mode dynamic fracture of self-compacting steel-fiber reinforced concrete. The specimens were prismatic beams for three-point bending tests, plain and reinforced with three fiber ratios (up to 0.6% in volume). They were sawn a notch cutting half of the depth at 1/4 of the span. Tests were performed at four loading rates: 2.2×10 -3 and 2.2 mm/s in a servo-hydraulic machine; 1.7×10 3 and 2.7×10 3 mm/s in a drop-weight device. The latter ones were recorded with a high-speed video camera. Results show that both the peak load and the inclination of the crack increase for faster rates. Besides, highly reinforced beams exhibit profuse crack branching for all the rates. As the fiber ratio increases, it is also observed that the main crack may either bifurcate or abruptly change its path when it gets closer to the loading point.
{"title":"Dynamic Mixed-Mode Fracture of Self-Compacting Steel-Fiber Reinforced Concrete","authors":"G. Ruiz","doi":"10.21012/FC10.233361","DOIUrl":"https://doi.org/10.21012/FC10.233361","url":null,"abstract":"This work studies the influence of fiber content and loading rate on the mixed-mode dynamic fracture of self-compacting steel-fiber reinforced concrete. The specimens were prismatic beams for three-point bending tests, plain and reinforced with three fiber ratios (up to 0.6% in volume). They were sawn a notch cutting half of the depth at 1/4 of the span. Tests were performed at four loading rates: 2.2×10 -3 and 2.2 mm/s in a servo-hydraulic machine; 1.7×10 3 and 2.7×10 3 mm/s in a drop-weight device. The latter ones were recorded with a high-speed video camera. Results show that both the peak load and the inclination of the crack increase for faster rates. Besides, highly reinforced beams exhibit profuse crack branching for all the rates. As the fiber ratio increases, it is also observed that the main crack may either bifurcate or abruptly change its path when it gets closer to the loading point.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"206 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":"129945109","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}
: Extrusion-based additive manufacturing of cementitious material is a promising technology for the future of construction. Nevertheless, new solutions need to be proposed to provide either ductility or even reinforcement in areas in tension. Using fibres to reinforce the structure made by extrusion seems to be promising and needs to be fully understood at different scales. Moreover, the efficiency of reinforcement depends mainly on the interfacial properties between matrix and fibres. Decohesion between matrix and fibre is studied at two different scales. A mesoscopic analytical mechanical model of a so-called tension stiffening test has been proposed to quantify resistance and friction along the interface from the force-elongation curve. Secondly, the same experimental test is performed inside the microtomography setup of the Anatomix beamline of Synchrotron Soleil permitting to identify the microscopic nature, shape and the evolution of decohesion between matrix and fibres for different loading. Different types of fibres are compared and different damaging mechanisms are observed.
{"title":"Characterisation and modelling of interfacial damage in fibre-reinforced concrete for 3D printing in construction","authors":"N. Ducoulombier","doi":"10.21012/FC10.235562","DOIUrl":"https://doi.org/10.21012/FC10.235562","url":null,"abstract":": Extrusion-based additive manufacturing of cementitious material is a promising technology for the future of construction. Nevertheless, new solutions need to be proposed to provide either ductility or even reinforcement in areas in tension. Using fibres to reinforce the structure made by extrusion seems to be promising and needs to be fully understood at different scales. Moreover, the efficiency of reinforcement depends mainly on the interfacial properties between matrix and fibres. Decohesion between matrix and fibre is studied at two different scales. A mesoscopic analytical mechanical model of a so-called tension stiffening test has been proposed to quantify resistance and friction along the interface from the force-elongation curve. Secondly, the same experimental test is performed inside the microtomography setup of the Anatomix beamline of Synchrotron Soleil permitting to identify the microscopic nature, shape and the evolution of decohesion between matrix and fibres for different loading. Different types of fibres are compared and different damaging mechanisms are observed.","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":"129049744","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":"Mesoscale analysis for the bond behavior of concrete under active confinement using coupled RBSM and solid FEM","authors":"M. Karam","doi":"10.21012/FC10.235473","DOIUrl":"https://doi.org/10.21012/FC10.235473","url":null,"abstract":"","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"63 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":"127910373","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}
. Combinations of damage mechanics and the theory of plasticity have shown to be suitable for modelling concrete’s quasi-brittle response in tension and low-confined compression, as well as the ductile response in confined compression. In this work, the recently proposed damage-plasticity constitutive model CDPM2 has been extended to the modelling of plain and reinforced concrete subjected to dynamic loading by making the damage part dependent on the strain rate. The approach is then applied to a dynamic compact tension test and a slab subjected to air blast loading for both of which experimental results have been reported in the literature.
{"title":"Modelling the dynamic response of concrete with the damage plasticity model CDPM2","authors":"P. Grassl","doi":"10.21012/FC10.235633","DOIUrl":"https://doi.org/10.21012/FC10.235633","url":null,"abstract":". Combinations of damage mechanics and the theory of plasticity have shown to be suitable for modelling concrete’s quasi-brittle response in tension and low-confined compression, as well as the ductile response in confined compression. In this work, the recently proposed damage-plasticity constitutive model CDPM2 has been extended to the modelling of plain and reinforced concrete subjected to dynamic loading by making the damage part dependent on the strain rate. The approach is then applied to a dynamic compact tension test and a slab subjected to air blast loading for both of which experimental results have been reported in the literature.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"103 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":"121394770","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 this study, an extended Rigid-Body-Spring Model (RBSM) considering geometric nonlinearity including finite rotation is developed based on an equivalence between the RBSM and the reduced integration Timoshenko beam element in order to simulate not only damage localization behavior but also large displacement and large rotation collapse behavior of reinforced concrete structures. Firstly, an elastic buckling response of a column is simulated by using the proposed method. By comparing the simulation result and the exact solution, it is confirmed that the proposed model can reproduce the large displacement and large rotation behavior in the elastic range. In addition, several numerical simulations of failure behavior of concrete and reinforced concrete members are presented. It is also confirmed that the model can simulate localized damage, rebar buckling and large rotational collapse behavior.
{"title":"Collapse simulation of reinforced concrete including localized failure and large rotation using extended RBSM","authors":"Y. Yamamoto","doi":"10.21012/FC10.235632","DOIUrl":"https://doi.org/10.21012/FC10.235632","url":null,"abstract":"In this study, an extended Rigid-Body-Spring Model (RBSM) considering geometric nonlinearity including finite rotation is developed based on an equivalence between the RBSM and the reduced integration Timoshenko beam element in order to simulate not only damage localization behavior but also large displacement and large rotation collapse behavior of reinforced concrete structures. Firstly, an elastic buckling response of a column is simulated by using the proposed method. By comparing the simulation result and the exact solution, it is confirmed that the proposed model can reproduce the large displacement and large rotation behavior in the elastic range. In addition, several numerical simulations of failure behavior of concrete and reinforced concrete members are presented. It is also confirmed that the model can simulate localized damage, rebar buckling and large rotational collapse behavior.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"41 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":"122681826","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":"Numerical Study on Shear Behaviours of ECC Beams Reinforced with FRP Bars","authors":"D. Gu","doi":"10.21012/FC10.233096","DOIUrl":"https://doi.org/10.21012/FC10.233096","url":null,"abstract":"","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"14 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":"115592154","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 present article describes a model, based on concepts of Fracture Mechanics, to evaluate the behavior of fiber reinforced concrete (FRC) sections. It is developed by an analytical method that represents tension in concrete by means of the linear softening law (σ-w) included in the Model Code 2010. The method also uses a compatibility equation for the cracked zone based on the planar crack hypothesis, i.e. the assumption that the crack surfaces remain plane throughout the fracture process, in conjunction with the Navier’s hypothesis applied only to the non-cracked zone. The model reproduces the experimental size-effect on the rupture-modulus for concrete and FRC sections and points at Hillerborg’s brittleness number as a common characterization parameter for concrete and FRC sections behavior. The study concludes that planar crack assumption can be considered as an alternative to Navier’s hypothesis, since it gives a more physical approximation to the FRC fracture behavior.
{"title":"Planar crack assumption as an alternative to Navier's hypothesis in the modelling of fibre-reinforced concrete sections","authors":"J. Carmona","doi":"10.21012/FC10.233086","DOIUrl":"https://doi.org/10.21012/FC10.233086","url":null,"abstract":"The present article describes a model, based on concepts of Fracture Mechanics, to evaluate the behavior of fiber reinforced concrete (FRC) sections. It is developed by an analytical method that represents tension in concrete by means of the linear softening law (σ-w) included in the Model Code 2010. The method also uses a compatibility equation for the cracked zone based on the planar crack hypothesis, i.e. the assumption that the crack surfaces remain plane throughout the fracture process, in conjunction with the Navier’s hypothesis applied only to the non-cracked zone. The model reproduces the experimental size-effect on the rupture-modulus for concrete and FRC sections and points at Hillerborg’s brittleness number as a common characterization parameter for concrete and FRC sections behavior. The study concludes that planar crack assumption can be considered as an alternative to Navier’s hypothesis, since it gives a more physical approximation to the FRC fracture behavior.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"38 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":"132330450","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 this paper a numerical model for autogenous healing of normal strength concrete is presented in detail, along with preliminary results of its validation, which is planned to be achieved by comparing the results of numerical analyses with those of a dedicated experimental campaign. Recently the SMM (Solidification-Microprestress-Microplane model M4) model for concrete, which makes use of a modified microplane model M4 and the solidification-microprestress theory, has been extended to incorporate the autogenous healing effects. The moisture and heat fields, as well as the hydration degree, are obtained from the solution of a hygro-thermo-chemical problem, which is coupled with the SMM model. The updated model can also simulate the effects of cracking on the permeability and the restoring effect of the self-healing on the mechanical constitutive laws, i.e. the microplane model. In this work, the same approach is introduced into a discrete model, namely the Lattice Discrete Particle Model (LDPM). A numerical example is presented to validate the proposed computational model employing experimental data from a recent test series undertaken at Politecnico di Milano.
{"title":"Modelling of autogenous healing for regular concrete via a discrete model","authors":"A. Cibelli","doi":"10.21012/FC10.235542","DOIUrl":"https://doi.org/10.21012/FC10.235542","url":null,"abstract":"In this paper a numerical model for autogenous healing of normal strength concrete is presented in detail, along with preliminary results of its validation, which is planned to be achieved by comparing the results of numerical analyses with those of a dedicated experimental campaign. Recently the SMM (Solidification-Microprestress-Microplane model M4) model for concrete, which makes use of a modified microplane model M4 and the solidification-microprestress theory, has been extended to incorporate the autogenous healing effects. The moisture and heat fields, as well as the hydration degree, are obtained from the solution of a hygro-thermo-chemical problem, which is coupled with the SMM model. The updated model can also simulate the effects of cracking on the permeability and the restoring effect of the self-healing on the mechanical constitutive laws, i.e. the microplane model. In this work, the same approach is introduced into a discrete model, namely the Lattice Discrete Particle Model (LDPM). A numerical example is presented to validate the proposed computational model employing experimental data from a recent test series undertaken at Politecnico di Milano.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"23 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":"121606021","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}
This paper addresses the degradation due to neutron radiation exposures of concrete consisting in various rock-forming silicate-based aggregates and cement paste. We are interested in the evaluation of the residual elastic properties of concretes subjected to a high fluence of fast neutron irradiation by means of an extended composite sphere model. We first introduce briefly the main features of the model, and then show how the damage resulting from the aggregate expansion generated by their physical and structural changes upon irradiation can be captured and accounted for. To validate the established analytical solutions of the model and illustrate its predicting performance, we apply it on two specific concretes: (1) a concrete consisting of an ordinary cement paste and silicate-based aggregates of various sizes; and (2) a concrete consisting of massive serpentine aggregates and a pure aluminous cement paste. In both cases, the model predictions are compared with the available experimental measurements, and a good accordance between them is found. The composite sphere model gives a full description of the damage development in the mortar and identifies the primary role of the aggregate expansion on the material degradation mechanisms. In this first attempt, only damage in the mortar is accounted for in the modelling while the aggregates are assumed to behave elastically.
{"title":"Evaluation of residual elasticity of an internal expansion-induced concrete","authors":"F. Chen","doi":"10.21012/FC10.235643","DOIUrl":"https://doi.org/10.21012/FC10.235643","url":null,"abstract":"This paper addresses the degradation due to neutron radiation exposures of concrete consisting in various rock-forming silicate-based aggregates and cement paste. We are interested in the evaluation of the residual elastic properties of concretes subjected to a high fluence of fast neutron irradiation by means of an extended composite sphere model. We first introduce briefly the main features of the model, and then show how the damage resulting from the aggregate expansion generated by their physical and structural changes upon irradiation can be captured and accounted for. To validate the established analytical solutions of the model and illustrate its predicting performance, we apply it on two specific concretes: (1) a concrete consisting of an ordinary cement paste and silicate-based aggregates of various sizes; and (2) a concrete consisting of massive serpentine aggregates and a pure aluminous cement paste. In both cases, the model predictions are compared with the available experimental measurements, and a good accordance between them is found. The composite sphere model gives a full description of the damage development in the mortar and identifies the primary role of the aggregate expansion on the material degradation mechanisms. In this first attempt, only damage in the mortar is accounted for in the modelling while the aggregates are assumed to behave elastically.","PeriodicalId":329531,"journal":{"name":"Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures","volume":"28 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":"114546875","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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