Academic literature on the topic 'Concrete damaged plasticity'
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Journal articles on the topic "Concrete damaged plasticity"
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Hanif, M. U., Z. Ibrahim, K. Ghaedi, A. Javanmardi, and S. K. Rehman. "Finite Element Simulation of Damage In RC Beams." Journal of Civil Engineering, Science and Technology 9, no. 1 (April 30, 2018): 50–57. http://dx.doi.org/10.33736/jcest.883.2018.
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A concrete damage model has been incorporated in finite element code ABAQUS as concrete damaged plasticity model to examine the sensitivity of the damage, as ABAQUS has the model that is capable of stiffness degradation in cracking which is the basis of fracture mechanics. Nonlinear constitutive relationships for concrete and steel have been incorporated in the model. The static and dynamic response of the structure at 10 different damage levels is studied and the sensitivity of the damage model towards the presence of non-linearity has been discussed. The concrete damaged plasticity model is capable of predicting formation of cracks in concrete beams against any kind of loads, as the results match with the experimental results. It can be concluded that the concrete damaged plasticity is a versatile tool for modeling RC structures and careful choice of solution procedures for dynamic analysis can lead to accurate modeling of concrete using a few routine laboratory test results of the materials.
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Yang, Ke Jia, Zi Ling Xie, and Wei Li. "Application of RPC Constitutive Model in FEA." Applied Mechanics and Materials 578-579 (July 2014): 25–30. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.25.
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The damage evolution equation of RPC is established based on 2-parameter Weibull distribution. The constitutive relation of RPC is then calculated based on the damage evolution equation. The constitutive model of RPC is optimized by comparing experimental constitutive curve to models corresponding to different threshold strain. Based on the definition of damage index in ABAQUS, the damaged evolution equation in ABAQUS is recalculated based on the optimized constitutive relation. the concrete damaged plasticity model in ABAQUS is obtained using the aforementioned method. And the concrete damaged plasticity model is applied to three compression member and three simply supported beams with different reinforcements. The calculated stress-strain curve and deformation of three compression member and three beams is in accordance with the deformation characteristics of experiments, which verified the effectiveness of the proposed concrete damaged plasticity model of RPC.
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Ding, Hui, Jian Ping Wang, and Cheng Fan. "Application of Damaged Plasticity Model on Slab-Column Joints." Applied Mechanics and Materials 777 (July 2015): 13–17. http://dx.doi.org/10.4028/www.scientific.net/amm.777.13.
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By the analysis of reinforced concrete slab, combined with experiment tests the feasibility of damaged plasticity model for concrete. Using parametric analyses, further the plastic damage model of related parameters set methods were discussed, concrete dilatation Angle, viscous coefficient, tensile stiffness, tensile damage on the results, in order to the design of slab-column connections engineering personnel to provide the reference.
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Wu, Hai Lin, Xiao Fan Du, Shi He Qin, Yao Li, and Qun Li. "Influence of Concrete Tension Softening Properties on the Steel-Liner Reinforced Concrete Penstock." Applied Mechanics and Materials 275-277 (January 2013): 1544–48. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.1544.
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In combination with the practice of a large hydropower station, concrete damaged plasticity model is introduced into the steel-liner reinforced concrete penstock for the nonlinear analysis, the damage distribution rules of the surrounding concrete and the stresses of the steels are furtherly studied under the different tension softening characteristic curves, the conclusions can provide the reference for damage assessment of the surrounding concrete and the optimization allocation of the reinforcement for the penstock.
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Dulinska, Joanna M. "Cooling Tower Shell under Asynchronous Kinematic Excitation Using Concrete Damaged Plasticity Model." Key Engineering Materials 535-536 (January 2013): 469–72. http://dx.doi.org/10.4028/www.scientific.net/kem.535-536.469.
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The paper presents the analysis of the dynamic response of a cooling tower to moderate earthquake. To represent inelastic behavior of the concrete material of the tower under dynamic loading, the concrete damaged plasticity constitutive model was assumed. The model consists of the combination of non-associated multi-hardening plasticity and scalar damaged elasticity to describe the irreversible damage that occurs during the fracturing process. Two different models of seismic excitation were used. Initially, a classical model of uniform kinematic excitation was applied. In this model it was assumed that excitation at all supports was identical. Then, a model of non-uniform kinematic excitation, typical for large multiple-support structures, was introduced. In that model the wave passage along the foundation ring was taken into account. It occurred that the assumption of asynchronous excitation led to the increase of the dynamic response of the tower with respect to the assumption of uniform ground motion. The tensile damage (cracking) in some parts of the tower appeared and the stiffness of the concrete was degraded when non-uniformity of excitation was considered. This was due to the quasi-static effects resulting from changes of subsoil geometry during the shock. The analysis indicated that the classical assumption of uniform excitation may lead to non-conservative assessment of the dynamic response of the shell described with concrete damaged plasticity model.
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Hany, Najwa F., Elie G. Hantouche, and Mohamed H. Harajli. "Finite element modeling of FRP-confined concrete using modified concrete damaged plasticity." Engineering Structures 125 (October 2016): 1–14. http://dx.doi.org/10.1016/j.engstruct.2016.06.047.
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Ni, Zhen Qiang, and Qin Shu Cui. "Numerical Simulation of Z-Shaped Column Joints in RC Frame Based on Damage Plasticity Model." Applied Mechanics and Materials 777 (July 2015): 173–78. http://dx.doi.org/10.4028/www.scientific.net/amm.777.173.
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This research selected Z-shaped section column joints in RC frame as the investigating object and considered the mechanical parameters extracted from physical model test results, proposed the finite element model of concrete damaged plasticity. Combining concrete damage plasticity model parameters on ABAQUS of concrete constitutive relationship from appendix C of Code for design of concrete structures (GB50010-2010), add the concept of damage factor to Energy equivalence principle, construct finite element model of Z-shaped column joints in RC frame, and simulated the test process under horizontal cyclic loading. The analysis results indicate that the finite element model can perfectly simulate action. It can reflect the mechanical properties of Z-shaped column joints in frame under horizontal cyclic loading, which is proved correct and reliable.
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Han, Xue, and Zheng Liu. "Numerical Simulation on the Form of Reinforcement of Reinforced Concrete Beam with Openings." Applied Mechanics and Materials 444-445 (October 2013): 884–88. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.884.
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In order to research the stress performance of reinforced concrete beam with different forms of reinforcement around the openings, a numerical simulation on reinforced concrete beam with circle openings is made by using the finite element software. The constitutive relation of concrete offered by the 2010 edition of code for design of concrete structures and the concrete damaged plasticity model is adopted in this article. The damage factor is introduced in the process of modeling, which can reflect the damage of beams with different forms of reinforcement directly and help to reveal the failure mechanism of members. Thus we can propose the optimization of reinforcement method.
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Belyakov, Nikita, Olga Smirnova, Aleksandr Alekseev, and Hongbo Tan. "Numerical Simulation of the Mechanical Behavior of Fiber-Reinforced Cement Composites Subjected Dynamic Loading." Applied Sciences 11, no. 3 (January 26, 2021): 1112. http://dx.doi.org/10.3390/app11031112.
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The problem of damage accumulation in fiber-reinforced concrete to structures supporting underground workings and tunnel linings against dynamic loading is insufficiently studied. The mechanical properties were determined and the mechanism of destruction of fiber-reinforced concrete with different reinforcement parameters is described. The parameters of the Concrete Damaged Plasticity model for fiber-reinforced concrete at different reinforcement properties are based on the results of lab experiments. Numerical simulation of the composite concrete was performed in the Simulia Abaqus software package (Dassault Systemes, Vélizy-Villacoublay, France). Modeling of tunnel lining based on fiber-reinforced concrete was performed under seismic loading.
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Ahmed, Bilal, George Z. Voyiadjis, and Taehyo Park. "Damaged plasticity model for concrete using scalar damage variables with a novel stress decomposition." International Journal of Solids and Structures 191-192 (May 2020): 56–75. http://dx.doi.org/10.1016/j.ijsolstr.2019.11.023.
Full textDissertations / Theses on the topic "Concrete damaged plasticity"
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Navarro, Menargues Miguel. "Estudio numérico parametrizado del punzonamiento en losas de hormigón armado. Evaluación del refuerzo estructural." Doctoral thesis, Universidad de Alicante, 2018. http://hdl.handle.net/10045/83429.
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En el presente trabajo se aborda la tesis “Estudio paramétrico con FEM del refuerzo a punzonamiento de losas de hormigón armado”. Se trata de todo lo relacionado con el fenómeno resistente de punzonamiento en estructuras, especialmente en forjados construidos mediante hormigón armado. Se trata de cuatro apartados bien diferenciados. En este, el primero, se desarrolla la síntesis de la tesis, donde se marcan unos objetivos, seguido de una explicación detallada y descripción de este fenómeno mediante su estado del arte, que abarca el grueso de éste primer apartado, en el cual se describen, entre otros aspectos, las diferentes patologías producidas por el punzonamiento y casos de sucesos catastróficos que provocaron, la historia de los forjados y los principales estudios llevados a cabo sobre este fenómeno, y acabando con las principales resultados y conclusiones de la tesis. Después, el segundo y tercer apartado contienen los artículos publicados y no publicados, respectivamente, por capítulos. Por último, se desarrollan las conclusiones en el último y cuarto apartado.
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Onifade, Ibrahim. "Development of Energy-based Damage and Plasticity Models for Asphalt Concrete Mixtures." Doctoral thesis, KTH, Byggnadsmaterial, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-198663.
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Characterizing the full range of damage and plastic behaviour of asphalt mixtures under varying strain-rates and stress states is a complex and challenging task. One reason for this is partly due to the strain rate and temperature dependent nature of the material as well as the variation in the properties of the constituent materials that make up the composite asphalt mixture. Existing stress-based models for asphalt concrete materials are developed based on mechanics principles, but these models are, however, limited in their application for actual pavement analysis and design since rate dependency parameters are needed in the constitutive model to account for the influence of the strain rate on the stress-based yield and evolution criteria. Till date, we are yet to arrive at simple and comprehensive constitutive models that can be used to model the behaviour of asphalt mixture over a wide range of strain-rate which is experienced in the actual pavement sections. The aim of this thesis is to develop an increased understanding of the strength and deformation mechanism of asphalt mixtures through multi-scale modeling and to develop simple and comprehensive continuum models to characterize the non-linear behaviour of the material under varying stress-states and conditions. An analysis framework is developed for the evaluation of the influence of asphalt mixture morphology on its mechanical properties and response using X-Ray CT and digital image processing techniques. The procedure developed in the analysis framework is then used to investigate the existence of an invariant critical energy threshold for meso-crack initiation which serves as the basis for the development of a theory for the development of energy-based damage and plastic deformation models for asphalt mixtures. A new energy-based viscoelastic damage model is developed and proposed based on continuum damage mechanics (CDM) and the thermodynamics of irreversible processes. A second order damage variable tensor is introduced to account for the distributed damage in the material in the different principal damage directions. In this way, the material response in tension and compression can be decoupled and the effects of both tension- and compression stress states on the material behaviour can be accounted for adequately. Based on the finding from the energy-based damage model, an equivalent micro-crack stress approach is developed and proposed for the damage and fracture characterization of asphalt mixtures. The effective micro-crack stress approach takes account of the material stiffness and a critical energy threshold for micro-crack initiation in the characterization of damage and fracture properties of the mixture. The effective micro-crack stress approach is developed based on fundamental mechanics principles and it reduces to the Griffith's energy balance criterion when purely elastic materials are considered without the need for the consideration of the surface energy and a crack size in the determination of the fracture stress. A new Continuum Plasticity Mechanics (CPM) model is developed within the framework of thermodynamics to describe the plastic behaviour of asphalt concrete material with energy-based criteria derived for the initiation and evolution of plastic deformation. An internal state variable termed the "plasticity variable" is introduced to described the distributed dislocation movement in the microstructure. The CPM model unifies aspects of existing elasto-plastic and visco-plastic theories in one theory and shows particular strength in the modeling of rate-dependent plastic behaviour of materials without the need for the consideration of rate dependency parameters in the constitutive relationships. The CPM model is further extended to consider the reduction in the stiffness properties with incremental loading and to develop a unified energy-based damage and plasticity model. The models are implemented in a Finite Element (FE) analysis program for the validation of the models. The result shows that the energy-based damage and plastic deformation models are capable of predicting the behaviour of asphalt concrete mixtures under varying stress-states and strain-rate conditions. The work in this thesis provides the basis for the development of more fundamental understanding of the asphalt concrete material response and the application of sound and solid mechanics principles in the analysis and design of pavement structures.En heltäckande karakterisering av skador och plastiska beteende hos asfaltblandningar under varierande belastningshastighet och spänningstillstånd är en komplex och svår uppgift. En orsak till detta är relaterat till materialets belastningshastighet- och temperaturberoende, såväl som variationen i materialegenskaperna hos de ingående komponenterna i den sammansatta asfaltblandningen. Befintliga spänningsbaserade modeller för asfaltbetongmaterial är utvecklade baserade på mekanikprinciper, men dessa modeller är begränsade när det gäller analys och design av verkliga asfaltsbeläggningar eftersom hastighetsberoende parametrar behövs i den konstitutiva modellen även med hänsyn till töjningshastighetens inverkan på kriterier för gränser och utveckling av spänningstillstånd. Det finns därför behov av att utveckla enkla men ändå heltäckande konstitutiva modeller som kan användas för att modellera beteendet hos asfaltmassan över ett brett spektrum av belastningshastigheter för olika av sektioner asfaltsbeläggningar. Syftet med denna avhandling är att öka förståelsen av hållfasthets- och deformationsmekanismer för asfaltblandningar genom multi-modellering. Målet är att utveckla enkla och heltäckande kontinuummodeller som karakteriserar materialets olinjära beteende under varierande spänningstillstånd och betingelser. Ett analysramverk har utvecklats för utvärdering av påverkan av asfaltmassans morfologi på dess mekaniska egenskaper och beteende med hjälp av röntgendatortomografi och digital bildbehandlingsteknik. Detta förfarande har sedan använts för att undersöka förekomsten av inneboende kritiska tröskelvärden för brottenergin för mesosprickinitiering vilket i sin tur ligger till grund för utvecklingen av en teori för modellering av energibaserade skador och plastisk deformation hos asfaltblandningar. En ny energidensitet baserad viskoelastisk skademodell utvecklas och föreslås utgå från kontinuum-skade-mekanik (CDM) och termodynamik för irreversibla processer. En andra ordningens skadevariabeltensor införs för att ta hänsyn till skadedistributionen i materialen i de olika principiella skaderiktningarna. På detta sätt kan materialets respons i drag- och tryckbelastning separeras och effekterna av spänningstillstånd i både drag och tryck kan beaktas på ett adekvat sätt. Baserat på resultaten från den energibaserade skademodellen utvecklas och föreslås en motsvarande metod för mikrosprickspänning gällande skade- och brottkarakteriseringen av asfaltblandningar. Metoden för den effektiva mikrosprickspänningen tar hänsyn till materialets styvhet och en kritisk tröskelenergi för mikrosprickinitiering för karakteriseringen av skador och brottegenskaper hos blandningen. Denna metod är utvecklad baserat på grundläggande mekanikprinciper och kan för rent elastiska material reduceras till Griffiths energibalanskriterium utan hänsyn till ytenergi och sprickstorlek vid bestämningen av brottspänningen. En ny termodynamikbaserad modell för kontinuumplasticitetsmekanik (CPM) utvecklas för att beskriva det plastiska beteendet hos asfaltbetongmaterial med energibaserade kriterier härledda för initiering och progression av plastisk deformation. En intern tillståndsvariabel kallad "plasticitetvariabeln" införs för att beskriva den fördelade dislokationsrörelsen i mikrostrukturen. CPM-modellen förenar befintliga elasto-plastiska och visko-plastiska teorier i en teori och visar sig vara särskilt effektiv i modelleringen av hastighetsberoende plastiskt beteende hos material utan att behöva beakta hastighetsberoende parametrar i de konstitutiva sambanden. CPM-modellen utvidgas ytterligare för att kunna beakta reduktionen av styvheten med stegvis ökad belastning och för att utveckla en enhetlig energibaserad skade- och plasticitetmodell. Modellerna är implementerade i ett finit element (FE)-analysprogram för validering av modellerna. Resultatet visar att de energibaserade modellerna för skador och plastisk deformation kan förutsäga beteendet hos asfaltbetongblandningar under varierande spänningstillstånd och töjningshastighetsförhållanden. Arbetet i denna avhandling utgör grunden för utvecklingen av mer grundläggande förståelse av asfaltbetongmaterialets respons och tillämpningen av sunda och robusta mekanikprinciper i analys och design av asfaltstrukturer.
QC 20161220
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Santos, Fernanda de Oliveira. "Modelo constitutivo incremental explícito para o concreto confinado baseado na teoria da plasticidade e dano." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-10072018-114442/.
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O confinamento de pilares de concreto por meio de camisas de aço ou compósitos possui uma função importante na preservação, recuperação e reforço de estruturas, pois proporciona aumento de resistência e ductilidade desses elementos estruturais. Porém, grande parte dos modelos existentes apresenta limitações na previsão do comportamento do concreto confinado, principalmente por serem dependentes do tipo de confinamento. Portanto, este trabalho apresenta um modelo para descrição do comportamento tensão-deformação do concreto submetido a qualquer tipo de confinamento uniforme, ativo ou passivo, e confinado com diferentes materiais confinantes - aço ou compósitos. O modelo constitutivo associa plasticidade e dano a fim de prever adequadamente a resistência, deformabilidade e redução de rigidez elástica do concreto confinado. O modelo é desenvolvido para um processo incremental explícito de implementação, permitindo, portanto, o seu desenvolvimento em qualquer tipo de planilha. Finalmente, o modelo foi validado por meio de um conjunto representativo de experimentos encontrados na literatura.Confinement of concrete columns through steel or composites jackets has an important function in the preservation, recovery and strengthening of structures, because it provides increased strength and ductility of these structural elements. However, most of the existing models have limitations in the prediction of the behavior of confined concrete, mainly because they are dependent on the type of confinement. This work presents a model for the description of the stress-strain behavior of the concrete submitted to any type of uniform confinement, active or passive, and confined with different confinement materials, steel or composites. The constitutive model associates plasticity and damage in order to predict with accuracy the strength, ultimate strain and reduction of elastic stiffness of the confined concrete. The model is developed by an explicit incremental implementation process allowing, therefore, its development in any type of spreadsheet. Finally, the model was validated through a representative set of experiments found in the literature.
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Nguyen, Giang Dinh. "A thermodynamic approach to constitutive modelling of concrete using damage mechanics and plasticity theory." Thesis, University of Oxford, 2005. http://ora.ox.ac.uk/objects/uuid:242564ff-cd6f-4743-8e06-0d3db5f44c3d.
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Recent advances in computational mechanics have opened the potential of carrying out the analysis and design of concrete structures in a realistic manner with the use of nonlinear concrete models. This encourages the development of more capable and realistic constitutive models, based on a rigorous approach, for the analysis and design of concrete structures. This research focuses on the development of a thermodynamic approach to constitutive modelling of concrete, with emphasis on the rigour and consistency both in the formulation of constitutive models, and in the identification of model parameters based on experimental tests. The key feature of the thermodynamic framework used in this study is that all behaviour of the defined model can be derived from two specified energy potentials. In addition, the derivation of a constitutive model within this framework merely follows procedures established beforehand. The proposed constitutive model here is based on continuum damage mechanics, in combination with plasticity theory, hence enabling the macroscopic material behaviour observed in experiments to be appropriately modelled. Damage-induced softening is the cause of many problems in numerical failure simulations based on conventional continuum mechanics. The resolution of these problems requires an appropriate special treatment for the constitutive modelling which, in this study, is based on nonlocal theory, and realized through the nonlocality of energy terms in the damage loading functions. For practical applications in structural analysis, the model requires a minimum number of parameters, which can be identified from experimental tests. All the above features of the model have been incorporated in a unified and consistent thermodynamic approach, which also distinguish the approach from existing ones. Numerical implementation and application are important parts of the study. A suitable implicit scheme is adapted here for the integration of the nonlocal rate constitutive equations. For the solution of systems of nonlinear algebraic equations in finite element analysis, the arc-length method in combination with local constraint equations employing dominant displacements is implemented, and proves its reliability in this study. Application of the proposed constitutive models in the analysis and design of concrete structures is straightforward, with several numerical examples showing the practical aspects of the proposed modelling.
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Pereira, Júnior Wanderlei Malaquias. "Análise numérica de estruturas de concreto com fibras utilizando mecânico do dano." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/4377.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The work is a contribution to the mechanical numerical modeling of concrete structures with steel fibers using constitutive models based on Damage Mechanics behavior. The same, presents the formulation of a model proposed Damage admits that the concrete as initially isotropic elastic material, but with the evolution of the damage process, the material exhibits plastic deformations, anisotropy and bimodularidad induced damage. The incorporation of fibers in the modeling is performed through a homogenization procedure. The constitutive model for the concrete as well as the homogenization technique for dealing with the case of fiber concrete are implemented on a structural analysis program bar finite element laminated in layers. The parametric identification of the constitutive model together with the proposed homogenization is carried out using experimental results from the literature. Finally, numerical analysis of reinforced concrete beams reinforced with steel fibers and subjected to bending are conducted to assess the applicability of the constitutive model considered in this work. An attempt is thus contribute to the study of the deformation of fibrous concrete beams in service, in order to aggregate results and discussions in a future proposal of Brazilian technical standard for this type of structure.
O trabalho trata de uma contribuição à modelagem numérica do comportamento mecânico de estruturas de concreto com fibras de aço utilizando modelos constitutivos baseados na Mecânica do Dano. O mesmo, apresenta a formulação de um modelo de Dano proposto que admite o concreto como material inicialmente isótropo e elástico, mas com a evolução do processo de danificação o material exibe deformações plásticas, anisotropia e bimodularidade induzidas pelo dano. A incorporação das fibras na modelagem é efetuada através de um procedimento de homogeneização. O modelo constitutivo para o concreto, assim como a técnica de homogeneização para tratar do caso do concreto com fibras são implementados em um programa para análise de estruturas de barras com elementos finitos estratificados em camadas. A identificação paramétrica do modelo constitutivo, juntamente com a proposta de homogeneização, é realizada utilizando resultados experimentais encontrados na literatura. Por fim, análises numéricas de vigas de concreto armado reforçado com fibras de aço e sujeitas à flexão são conduzidas no sentido de avaliar a aplicabilidade do modelo constitutivo tratado neste trabalho. Procura-se, assim, contribuir para o estudo da deformabilidade de vigas de concreto fibroso em serviço, com o intuito de agregar resultados e discussões numa futura proposta de norma técnica brasileira para este tipo de estrutura.
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Wang, Xiaofeng. "Computational technology for damage and failure analysis of quasi-brittle materials." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/computational-technology-for-damage-and-failure-analysis-of-quasibrittle-materials(a7c91eb6-5058-4e73-95de-b2f3efd645d2).html.
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The thesis presents the development and validation of novel computational technology for modelling and analysis of damage and failure in quasi-brittle materials. The technology is demonstrated mostly on concrete, which is the most widely used quasi-brittle material exhibiting non-linear behaviour. Original algorithms and procedures for generating two-dimensional (2D) and three-dimensional (3D) heterogeneous material samples are developed, in which the mesoscale features of concrete, such as shape, size, volume fraction and spatial distribution of inclusions and pores/voids are randomised. Firstly, zero-thickness cohesive interface elements with softening traction-separation relations are pre-inserted within solid element meshes to simulate complex crack initiation and propagation. Monte Carlo simulations (MCS) of 2D and 3D uniaxial tension tests are carried out to investigate the effects of key mesoscale features on the fracture patterns and load-carrying capacities. Size effect in 2D concrete is then investigated by finite element analyses of meso-structural models of specimens with increasing sizes. Secondly, a 3D meso-structural damage-plasticity model for damage and failure analysis of concrete is developed and applied in tension and compression. A new scheme for identifying interfacial transition zones (ITZs) in concrete is presented, whereby ITZs are modelled by very thin layers of solid finite elements with damage-plasticity constitutive relations. Finally, a new coupled method named non-matching scaled boundary finite element-finite element coupled method is proposed to simulate crack propagation problems based on the linear elastic fracture mechanics. It combines the advantage of the scaled boundary finite element method in modelling crack propagation and also preserves the flexibility of the finite element method in re-meshing. The efficiency and effectiveness of the developed computational technology is demonstrated by simulations of crack initiation and propagation problems.
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Vosoughian, Saeed. "The effect of pre-stressing location on punching shear capacity of concrete flat slabs." Thesis, KTH, Betongbyggnad, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263243.
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Implementing pre-stressing cables is a viable option aiming at controlling deformation and cracking of concrete flat slabs in serviceability limit state. The pre-stressing cables also contribute to punching shear capacity of the slab when they are located in vicinity of the column. The positive influence of pre-stressing cables on punching capacity of the concrete slabs is mainly due to the vertical component of inclined cables, compressive in-plane stresses and counter acting bending moments near the support region. The method presented in Eurocode 2 to determine the punching capacity of the pre-stressed concrete flat slabs considers the in-plane compressive stresses but totally neglects the effect of counter acting moments. The effect of vertical forces introduced by inclined cables is only considered when they are within the distance 2d from the face of the column. This area is called basic control area in the Eurocode 2. In this master thesis nonlinear finite element analysis is carried out to study the effect of pre-stressing cables on punching shear capacity of concrete slabs respecting the distance of cables from the face of the column. To attain this objective, the concrete damage plasticity model is implemented to model the concrete. The results indicate that until the distance of 6d from the face of the column the contribution of pre-stressing cables in punching shear capacity of slabs is significant. Furthermore, comparing the numerical results with the punching shear capacity of slabs predicted by Eurocode 2 reveals that Eurocode tremendously underestimates the punching shear capacity when the cables are located outside the basic control area.
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Nana, Wendpanga Serge Auguste. "Etudes expérimentales et numériques du comportement des dalles épaisses en béton armé sous chargement de cisaillement et interaction cisaillement/effet de membrane : Application aux bâtiments nucléaires." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI108/document.
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Cette contribution, en s’appuyant sur expérimentation et modélisation numérique vise à une meilleure compréhension du comportement des dalles en béton armé sous sollicitations de cisaillement. Une campagne expérimentale a été réalisée sur des dalles épaisses à pleine échelle de centrales nucléaires. Ces dalles sans armatures d’effort tranchant sont soumises à une sollicitation de cisaillement en chargement quasi-statique. Les essais sont réalisés en faisant varier différents paramètres qui peuvent influencer le comportement au cisaillement. Sont ainsi étudiés : résistance en compression du béton, épaisseur, taux d’armatures longitudinales et transversales, taille des granulats, longueur de la plaque de chargement. L’influence des efforts de membrane, de compression ou de traction, sur le comportement au cisaillement a également été analysée. Les résultats des essais sont ensuite comparés aux prédictions des codes de calcul. Ces résultats ont d’abord permis d’apporter une réponse aux divergences qui existent entre l’Eurocode 2 et l’Annexe Nationale Française quant à la prédiction du cisaillement. Ont également été évalués le niveau de précision donné par d’autres normes de dimensionnement au cisaillement: la norme américaine ACI 318-14, le code nucléaire AFCEN ETC-C 2010, le fib-Model Code 2010 et l’approche par la théorie de la fissure critique de cisaillement CSCT. Ensuite est évalué la possibilité d’analyses non-linéaire par élément finis (EF) pour reproduire le phénomène du cisaillement dans les dalles. Un modèle de béton élastoplastique avec endommagement est combiné à une analyse quasi-statique à schéma de résolution explicite. Des lois de comportement non linéaires appropriées du béton avec des comportements post-pic associés à un critère énergétique ont été considérées. La bonne concordance entre le modèle proposé et les résultats expérimentaux en termes de résistance au cisaillement et de modes de rupture permet de valider la modélisation proposée. Une étude paramétrique a été réalisée sur la base du modèle proposé avec les mêmes propriétés mécaniques de béton. Des lois simplifiées permettant d’estimer les capacités en cisaillement en fonction des différents paramètres étudiés sont finalement proposéesThis study, based on experiments and numerical modeling, aims at a better understanding of the shear behavior of reinforced concrete slabs. An experimental campaign was carried out on full-scale thick slabs typical of nuclear power plant slabs. These slabs without shear reinforcement are subjected to a quasi-static shear loading. The tests are carried out by varying different parameters that can influence the shear behavior: the concrete compressive strength, the slab depth, the bottom longitudinal and transverse reinforcement ratio, the concrete aggregate size, the loading plate length. The influence on shear behavior of compression or tension membrane forces has also been analyzed. The results of tests are then compared with the predictions of the calculation codes. These results first of all helped to answer the differences between the Eurocode 2 and the French National Annex concerning the prediction of the shear capacity of reinforced concrete slabs. The level of accuracy given by other shear dimensioning standards was also assessed: The American standard ACI 318-14, the AFCEN ETC-C 2010 code used for nuclear buildings, the fib-Model 2010 and the Critical Shear Crack Theory. Next, we evaluate the possibilities of a non-linear finite element analysis (EF) to reproduce the phenomenon of shear in slabs. An elastoplastic concrete model with damage was used and combined with a quasi-static analysis using an explicit resolution scheme. Appropriate nonlinear behavior laws of concrete with post-peak behaviors associated with an energy criterion were considered. The good agreement between the proposed model and the experimental results in terms of shear strength and failure modes allowed validating the proposed modeling. A parametric study was conducted based on the numerical proposed model with the same mechanical properties of concrete. Simplified laws allowing estimating the shear capacities according to the different parameters studied are proposed
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Qsymah, Ansam. "In-situ X-ray computed tomography tests and numerical modelling of ultra high performance fibre reinforced concrete." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/insitu-xray-computed-tomography-tests-and-numerical-modelling-of-ultra-high-performance-fibre-reinforced-concrete(7c27ef36-afc8-4ea7-8c72-7d92eba924f9).html.
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Ultra high performance fibre reinforced concrete (UHPFRC) is a relatively new fibre reinforced cementitious composite and has become very popular in construction applications. Extensive experimental studies have been conducted, demonstrating its superior properties such as much higher strength, ductility and durability than conventional fibre reinforced concrete (FRC) and high performance concrete. However, the material's damage and fracture mechanisms at meso/micro scales are not well understood, limiting its wider applications considerably. This study aims at an in-depth understanding of the damage and fracture mechanisms of UHPFRC, combining microscale in-situ X-ray computed tomography (µXCT) experiments and mesoscale image-based numerical modelling. Firstly, in-situ µXCT tests of small-sized UHPFRC specimens under wedge splitting loading were carried out, probably for the first time in the world, using an in-house designed loading rig. With a voxel resolution of 16.9µm, the complicated fracture mechanisms are clearly visualised and characterised using both 2D images and 3D volumes at progressive loading stages, such as initiating of micro-cracks, arresting of cracks by fibres, bending and pulling out of fibres and spalling of mortar at the exit points of inclined fibres. Secondly, based on the statistics of pores in the µXCT images obtained for a 20mm cube specimen, an efficient two-scale analytical-numerical homogenisation method was developed to predict the effective elastic properties of the UHPFRC. The large number of small pores were first homogenised at microscale with sand and cement paste, using elastic moduli from micro-indentation tests. 3D mesoscale finite element models were built at the second scale by direct conversion of the µXCT images, with fibres and large pores were faithfully represented. The effects of the volume fraction and the orientation of steel fibres on the elastic modulus were investigated, indicating that this method can be used to optimise the material micro-structure. Thirdly, 3D mesoscale finite element models were built for the specimen used in the in-situ µXCT wedge splitting test, with embedded fibre elements directly converted from the µXCT images. The fracture behaviour in the mortar was simulated by the damage plasticity model available in ABAQUS. Finally, 2D mesoscale finite element models were developed to simulate the fracture behaviour of UHPFRC using cohesive interface elements to simulate cracks in the mortar, and randomly distributed two-noded 1D fibres and connector elements to simulate the pull-out behaviour of fibres. This approach offers a link between the fibres pull-out behaviour and the response of the whole composite at the macroscale, thus it can be used to conduct parametric studies to optimise the material properties.
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Bülow, Angeling Jenny. "Weight reduction of concrete poles for the Swedish power line grid : Using a Finite Element Model to optimize geometry in relation to load requirements." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-66823.
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Because of an eventual ban of creosote-impregnated products, alternative materials for poles used in the electrical grid are needed. Concrete is one alternative and spun concrete poles have been manufactured for the Swedish grid before. These poles are still in use since the high strength and good functioning. However, they weigh too much in terms of the way that poles are assembled on the grid today. Therefore, a study comparing the capacity of different geometries, resulting in lower weight, is of interest. In this Master’s Thesis, crack initiation and compressive failure in concrete poles are examined by creating FE-models in the software BRIGADE/Plus, using concrete damage plasticity. Thus, guidance is provided about how thin the concrete walls can be made without risking failure – which also means how low the weight of such a pole can be. The failure most likely to occur is a compressive failure in the concrete with a ductile behavior. The result shows that a geometry change, which implies a thinner concrete wall, is possible. This means a weight reduction between 30-75 % or even more, depending on which network the poles are designed for.
Book chapters on the topic "Concrete damaged plasticity"
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Sannametla, Nidhi, and Jyosyula Sri Kalyana Rama. "Seismic Response of UHPC Strengthened Reinforced Concrete Frame Using Concrete Damaged Plasticity Model." In Lecture Notes in Civil Engineering, 159–71. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-4079-0_14.
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Mohamad-Hussein, Assef, and Jian Fu Shao. "Elastoplastic Damage Modelling and Failure Analysis of Concrete in Compression." In Engineering Plasticity and Its Applications, 1127–32. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-433-2.1127.
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Wu, Xiang Guo, Sang Mook Han, Sung Wook Kim, and Su Tae Kang. "Shear Failure Load of SFR-UHPCC I-Beam without Stirrup Based on Limit Analysis of Concrete Plasticity." In Fracture and Damage Mechanics V, 491–94. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-413-8.491.
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Vorlet, S., P. Manso, and G. De Cesare. "Seismic Behavior of Pine Flat Concrete Gravity Dam Using Microplane Damage-Plasticity Model." In Lecture Notes in Civil Engineering, 353–67. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-51085-5_19.
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Aymerich, F., L. Fenu, and G. Loi. "FE Analysis of the Flexural Behavior of Cementitious Composites Using the Concrete Damage Plasticity Model." In Lecture Notes in Civil Engineering, 124–33. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-23748-6_10.
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Chen, J. F., and Y. Tao. "Finite Element Modelling of FRP-to-Concrete Bond Behaviour Using the Concrete Damage Plasticity Theory Combined with a Plastic Degradation Model." In Advances in FRP Composites in Civil Engineering, 45–50. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-17487-2_7.
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Ali, Mohamed, Imadeddin Zreid, and Michael Kaliske. "Modeling of a Reinforced Concrete Column Under Cyclic Shear Loads by a Plasticity-Damage Microplane Formulation." In Design and Construction of Smart Cities, 13–21. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-64217-4_2.
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"A note on the ABAQUS Concrete Damaged Plasticity (CDP) model." In Civil, Architecture and Environmental Engineering, 1301–6. CRC Press, 2017. http://dx.doi.org/10.1201/9781315226187-239.
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Ghaedi, Khaled, Farzad Hejazi, Meisam Gordan, Ahad Javanmardi, Hamed Khatibi, and Ali Joharchi. "Seismic Response Characteristics of RCC Dams Considering Fluid-Structure Interaction of Dam-Reservoir System." In Computational Overview of Fluid Structure Interaction. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97859.
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In analysis of different types of dams, i.e. arch, gravity, rockfill and Roller Compacted Concrete (RCC) dams, the effect of hydrodynamic water pressure as an effective factor must seriously be taken into consideration. In present study, the hydrodynamic effect is precisely deliberated in RCC dams and compared to hydrostatic pressure effect. For this purpose, Kinta RCC dam in Malaysia is selected and 2D finite element (FE) model of the dam is performed. The Lagrangian approach is used to solve the dam-reservoir interaction, fluid–structure interaction (FSI), and in order to evaluate the crack pattern, Concrete Damaged Plasticity (CDP) model is implemented. Comparisons show that hydrodynamic pressure significantly changes the dam behaviour under seismic excitations. Moreover, the hydrodynamic effect modifies the deformation shape of the dam during the ground motions, however, it increases the magnitudes of the developed stresses causing more extensive tension crack damages mostly in the heel and upstream zones of the dam.
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Reynouard, J. M., O. Merabet, and J. L. Clément. "Steel-concrete interfaces: Damage and plasticity computations." In Studies in Applied Mechanics, 281–313. Elsevier, 1995. http://dx.doi.org/10.1016/s0922-5382(06)80015-2.
Full textConference papers on the topic "Concrete damaged plasticity"
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Genikomsou, Aikaterini, and Maria Anna Polak. "Damaged plasticity modelling of concrete in finite element analysis of reinforced concrete slabs." In 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures. IA-FraMCoS, 2016. http://dx.doi.org/10.21012/fc9.006.
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Li, W., and J. Wu. "A note on the ABAQUS Concrete Damaged Plasticity (CDP) model." In Proceedings of the International Conference on Civil, Architecture and Environmental Engineering (ICCAE2016). CRC Press/Balkema P.O. Box 11320, 2301 EH Leiden, The Netherlands: CRC Press/Balkema, 2017. http://dx.doi.org/10.1201/9781315116242-42.
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Yu, Hailing, and David Jeong. "Railroad Tie Responses to Directly Applied Rail Seat Loading in Ballasted Tracks: A Computational Study." In 2012 Joint Rail Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/jrc2012-74149.
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This paper describes work in-progress that applies the finite element (FE) method in predicting the responses of individual railroad crossties to rail seat pressure loading in a ballasted track. Both wood and prestressed concrete crossties are examined. The concrete tie is modeled as a heterogeneous medium with prestressing wires or strands embedded in a concrete matrix. The constitutive relations employed in the models are: elasticity followed by damaged plasticity for the concrete material, linear elastic bond-slip relations with potential initiation and evolution of damage to the bond for the steel-concrete interfaces, orthotropic elasticity followed by failure dictated by orthotropic stress criteria for the wood ties, extended Drucker-Prager plasticity for the granular and frictional ballast material, and elastic half space for the subgrade. The corresponding material parameters are obtained from the open literature. Under a simplified pressure load uniformly distributed over the rail seat area, the FE method predicts tensile cracking at the tie base below the rail seats of a concrete tie and compressive failure in the rail seats of a wood tie. The rail seat force-displacement relations are obtained from the simulations. The resultant rail seat forces at which tie failures occur are compared for concrete and wood ties. The FE method appears to be a promising tool for studying the railroad tie behavior under rail seat loading conditions in a ballasted track. Experimental data will be sought to calibrate the material parameters and verify the modeling approach. Additional track components, particularly rails, rail pads and fasteners, will be incorporated in future modeling efforts. This detailed modeling approach may help to shed light on the rail seat deterioration failure mechanisms observed in some concrete ties.
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Yu, Hailing, David Jeong, John Choros, and Ted Sussmann. "Finite Element Modeling of Prestressed Concrete Crossties With Ballast and Subgrade Support." In ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-47452.
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With the first major installation in North American railroads during the 1960’s, concrete ties were believed to last longer than timber ties and have the potential for reduced life cycle costs. However, their characteristic response to initial pretension release as well as dynamic track loading is not well understood. In North America, concrete ties have been found vulnerable to rail seat deterioration (RSD), but the mechanisms contributing to RSD failures are not well understood. To improve such understanding, a comprehensive computational study of the tie response to dynamic track forces is needed. This paper presents an initial research effort in this direction that models concrete crossties as heterogeneous media in three-dimensional finite element analyses, i.e., the prestressing strands, concrete matrix and the strand-concrete interfaces are represented explicitly. Damaged plasticity models are employed for the concrete material, and linear elastic bond-slip relations, followed by damage initiation and evolution, are adopted for the strand-concrete interfaces. Further, the ballast is modeled with an Extended Drucker-Prager plasticity model, and the subgrade is modeled as an elastic half space. All material parameters are obtained from the open literature. Currently the rail fastening systems are not included in modeling. Two loading scenarios are simulated: pretension release and direct rail seat loading. The modeling approach is able to predict the deformed tie shape, initial interface deterioration, the compressive stress state in concrete and residual tension in the strands upon pretension release. The transfer lengths of the prestressing strands can be readily calculated from the analysis results. Further predicted are the rail seat force-displacement characteristics and the potential failure mode of a concrete crosstie under direct rail seat loading. The responses of two railroad concrete crossties with 8-strand and 24-wire reinforcements, respectively, are studied using the presented modeling framework. The analyses indicate a potential failure mode of tensile cracking at the tie base below the rail seats. The results show that the 24-wire tie is better able to retain the pretension in the reinforcements than the 8-strand tie, resulting in slightly stronger rail seat force-displacement characteristics and higher failure load. The effects of the load application method and the subgrade modeling on the predicted tie response are further studied.
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Hou, Gangling, Chenning Song, Tianshu Song, and Guoliang Zhou. "Analysis of Factors Influencing Compressive Bearing Capacity of Nuclear Containment." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-15191.
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Nuclear containment protects nuclear island from serious accident, while its compressive bearing capacity remains the key problem to nuclear safety. With reference to one nuclear containment, the special concrete damaged plasticity model in software ABAQUS, this article systematically analyzes influencing rules of compressive bearing capacity and factors such as gravity, steel liner, prestressed tendons etc. The result shows that steel liner and prestressed tendons play key parts in deformation inhibition and the failure mode of nuclear containment, meanwhile prestressed tendons are crucial to improve the compressive bearing capacity.
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Yu, Hailing. "Finite Element Analysis of Contributing Factors to the Horizontal Splitting Cracks in Concrete Crossties Pretensioned With Seven-Wire Strands." In 2017 Joint Rail Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/jrc2017-2256.
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This paper employs the finite element (FE) modeling method to investigate the contributing factors to the “horizontal” splitting cracks observed in the upper strand plane in some concrete crossties made with seven-wire strands. The concrete tie is modeled as a concrete matrix embedded with prestressing steel strands. A damaged plasticity model that can predict the onset and propagation of tensile degradation is applied to the concrete material. An elasto-plastic bond model developed in-house is applied to the steel-concrete interface to account for the interface bond-slip mechanisms and particularly the dilatational effects that can produce the splitting forces. The pretension release process is simulated statically, followed by the dynamic simulations of cyclic rail seat loading. The concrete compressive strength at which the pretension in the strands is released, or release strength, affects both the concrete behavior and the bond characteristics. Three concrete release strengths, 3500, 4500 and 6000 psi, are considered in the simulations. Concrete tie models without and with a fastening system are developed and simulated to examine the effect of embedded fastener shoulders and fastener installation. The fastener shoulders are seated relatively deeply reaching between the two rows of strands. There is instant concrete material degradation adjacent to the strand interfaces near the tie ends upon pretension release. Without the fastening system in the model, the 3500 psi release strength leads to a high degree of degradation that is coalesced and continuous in the upper and lower strand planes, respectively. The damage profiles with the higher release strengths are more discrete and disconnected. Dynamic loading appears to increase the degree of degradation over time. In all cases, the upper strand plane is not dominant in the degree or the extent of material degradation, in contrast to the field observations that the horizontal splitting occurred in the upper strand plane only. Further simulations with the fastener model at 3500 psi concrete release strength indicate that the fastener installation process does not worsen the damage profile. However, the presence of fastener shoulders in the concrete matrix changes the stress distribution and redirects more concrete damages to the upper strand plane, while leaving disconnected damages in the lower strand plane. Under repeated dynamic rail loading, this potentially reproduces the exact upper strand plane, horizontal cracking pattern observed in the field. Subjected to further experimental verification, the FE analyses identify three contributing factors to the horizontal macro-cracks occurring at the specific upper strand level: (1) relatively low concrete release strength during production, (2) embedded fastener shoulders that redistribute concrete damages to the upper strand plane, and (3) a sufficiently large number of dynamic rail loading cycles for the microscopic damages to develop into macro-cracks. The number of dynamic loading cycles needed to produce macro-cracks should increase with the increased concrete release strength.
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ALMEIDA Jr, Sálvio A., and Serhan Guner. "Nonlinear Finite Element Analysis of Non-Structural Components Anchorage under Extreme Wind Loads." In IABSE Congress, New York, New York 2019: The Evolving Metropolis. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/newyork.2019.1905.
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<p>Steel anchors are widely used to fasten structures and non-structural components (NSC) to rooftop concrete slabs, especially in high-rise buildings. However, several NSC anchorage failures have been observed in the last decades upon the incidence of hurricanes, resulting in loss of service in essential buildings, detachment of the component, and water intrusion, all of which significantly delayed the recovery of the affected communities. From the observed failures, three main mechanisms were identified: steel rupture, concrete breakout, and bond failure. In this study, a three-dimensional nonlinear finite element methodology using a concrete damaged plasticity approach is developed to predict the response of steel anchors installed into a concrete slab. The methodology is verified with experimental results for each failure mechanism and subsequently used to study the effect of service-load concrete cracking and elevated temperatures – common conditions at rooftop level – on the response of the anchors. In addition, a first-of-its-kind multi-scale model of an NSC and its anchorage is created using the proposed methodology to investigate its behavior under dynamic hurricane load application. The findings suggest that these conditions can compromise the performance of NSC or promote its failure.</p>
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Yu, Hailing. "Estimating Deterioration in the Concrete Tie-Ballast Interface Based on Vertical Tie Deflection Profile: A Numerical Study." In 2016 Joint Rail Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/jrc2016-5783.
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In ballasted concrete tie track, the tie-ballast interface can deteriorate resulting in concrete tie bottom abrasion, ballast pulverization and/or voids in tie-ballast interfaces. Tie-ballast voids toward tie ends can lead to unfavorable center binding support conditions that can result in premature concrete tie failure and possible train derailment. Direct detection of these conditions is difficult. There is a strong interest in assessing the concrete tie-ballast interface conditions indirectly using measured vertical deflections. This paper seeks to establish a link between the vertical deflection profile of a concrete tie top surface and the tie-ballast interface condition using the finite element analysis (FEA) method. The concrete tie is modeled as a concrete matrix embedded with prestressing steel strands or wires. The configurations of two commonly used concrete ties, one with 8 prestressing strands and the other with 20 prestressing wires, are employed in this study. All models are three-dimensional and symmetric about the tie center. A damaged plasticity model that can predict onset and propagation of tensile cracks is applied to the concrete material. The steel-concrete interface is homogenized and represented with a thin layer of cohesive elements sandwiched between steel and concrete elements. Strand- or wire-specific elasto-plastic bond models developed at the Volpe Center are applied to the cohesive elements to account for the interface bonding mechanisms. FE models are developed for both original and worn concrete ties, with the latter assuming hypothetical patterns of reduced cross sections resulting from abrasive interactions with the ballast. Static analyses of pretension release in these concrete ties are conducted, and vertical deflection gradients along tie lengths are calculated and shown to correspond well with the worn cross sectional patterns for a given reinforcement type. The ballast is further modeled with Extended Drucker-Prager plasticity, and hypothetical voids are applied toward the tie ends along the concrete tie-ballast interface to simulate center binding support conditions. The distance range over which the concrete tie is supported in the center is variable and yields different center binding severity. Static simulations are completed with vertical rail seat loads applied on the concrete tie-ballast assembly. The influences of various factors on the vertical deflection profile, including tie type, vertical load magnitude, center binding severity, cross sectional material loss and prestress loss, are examined based on the FEA results. The work presented in this paper demonstrates the potential of using the vertical deflection profile of concrete tie top surfaces to assess deteriorations in the tie-ballast interface. The simulation results further help to clarify minimum technical requirements on inspection technologies that measure concrete tie vertical deflection profiles.
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Zeitouni, Adam I., Dimitris Rizos, and Yu Qian. "Benefits of Prestressed HSRM Concrete Ties for Center Binding Conditions." In 2018 Joint Rail Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/jrc2018-6219.
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Concrete ties have become a promising alternative to timber ties for freight lines with increased curvature, high annual traffic, and large axle loads. They are also widely adopted in passenger lines. High strength (HS) concrete is the material of choice in the fabrication of prestressed concrete railroad ties. The higher strength of the concrete is directly related to higher values of the Elastic Modulus, thus increasing the rigidity of the material. The combination of increased strength, rigidity, and the material brittleness may lead to the development of high amplitude stresses with high gradients, which appears to be a common underlying cause of premature cracking and deterioration observed in some concrete ties. Realizing the current issues associated with the performance of concrete ties and recalling the findings of an almost fifteen-year-old research conducted at the University of South Carolina (USC), a hypothesis was formulated that there is a potential benefit in introducing weathered granite aggregates into mix designs for railroad concrete ties. A high strength, yet lower rigidity, concrete will reduce the amplitude of the stress field and equally important, will regularize the stress field providing for a smoother load distribution that will diffuse stress concentrations. Consequently, the High Strength Reduced Modulus (HSRM) concrete improves the cracking resistance and fatigue performance, thus extending the life of the tie. A comprehensive research program has been conducted at USC to identify the benefits of using HSRM in concrete ties. The research is based on experimental investigations and computer simulations at the material, component and structural member levels. This work presents the details of the computer simulation studies that pertain to center binding conditions. Three-dimensional nonlinear Finite Element (FE) models have been developed for the HSRM and the “Standard” concrete ties. Nonlinear material models based on damaged plasticity are implemented. The concrete-steel bond interface is also modeled and discussed. Validation of these models is conducted through comparisons with laboratory testing of prestressed concrete prisms, and it has shown excellent accuracy. Subsequently, a study related to center binding conditions in a tangent track have been conducted. These studies showed that the HSRM concrete tie outperformed the Standard concrete tie in these benchmark tests by (i) showing smoother stress distribution, (ii) delaying the initiation of cracks and (iii) failing at higher ultimate loads. The analysis results are discussed and future recommendations presented.
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Briseghella, Bruno, Valeria Colasanti, Luigi Fenu, Camillo Nuti, Enrico Spacone, and Humberto Varum. "Nonlinear Static Analysis by Finite Elements of a Fujian Hakka Tulou." In IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/guimaraes.2019.1140.
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<p>Hakka Tulous are massive circular earth constructions of the Fujian Province, China, included in the UNESCO World Heritage list. They are subjected to earthquakes of medium magnitude, but their response to the seismic action is not yet investigated in depth. The seismic response of Fujian Tulous was herein investigated through pushover analysis modelling the Tulou structure by finite elements. Although the Tulou is a big construction with a circular earth wall of about fifty meters in diameter, a micromechanical approach was used to model the earth nonlinear behaviour. Even if no binder is added to the earthen material, the Concrete Damaged Plasticity model can be adopted and has shown to be effective in modelling its nonlinear behaviour, as well as the nonlinear response of the Tulou earth wall. Performing pushover analysis of a big earth structure using a micromechanical approach seems to give reliable results, that must be proved by future research.</p>