A plasticity and anisotropic damage model for plain concrete (original) (raw)
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Engineering Fracture Mechanics, 2010
A coupled plasticity-damage model for plain concrete is presented in this paper. Based on continuum damage mechanics (CDM), an isotropic and anisotropic damage model coupled with a plasticity model is proposed in order to effectively predict and simulate plain concrete fracture. Two different damage evolution laws for both tension and compression are formulated for a more accurate prediction of the plain concrete behavior. In order to derive the constitutive equations and for the easiness in the numerical implementation, in the CDM framework the strain equivalence hypothesis is adopted such that the strain in the effective (undamaged) configuration is equivalent to the strain in the nominal (damaged) configuration. The proposed constitutive model has been shown to satisfy the thermodynamics requirements. Detailed numerical algorithms are developed for the finite element implementation of the proposed coupled plasticity-damage model. The numerical algorithm is coded using the user subroutine UMAT and then implemented in the commercial finite element analysis program Abaqus. Special emphasis is placed on identifying the plasticity and damage model material parameters from loading–unloading uniaxial test results. The overall performance of the proposed model is verified by comparing the model predictions to various experimental data, such as monotonic uniaxial tension and compression tests, monotonic biaxial compression test, loading–unloading uniaxial tensile and compressive tests, and mixed-mode fracture tests.
International Journal of …, 2009
An anisotropic damage constitutive model for concrete is developed within the framework of elastoplasticity and continuum damage mechanics. The transformation from the effective (undamaged) to the damaged configuration in the elastic regime is obtained by using the hypothesis of elastic strain energy equivalence. Damage in plasticity is accounted for by developing a new formulation relating the plastic strains rate tensors in the effective and damaged configurations. Two anisotropic damage criteria are introduced to account for the different concrete behavior effects under tensile and compressive loadings. The total stress is decomposed into tensile and compressive components in order to satisfy these damage criteria. The plasticity yield criterion presented in this work accounts for the spectral decomposition of the stress tensor and will be used simultaneously with the damage criteria. The transformation of stresses from the effective to the damaged configuration is achieved by using a fourth order transformation tensor that is based on second order tensile and compressive damage tensors. Expressions are derived for the elastoplastic tangent operator in the effective and damaged configurations. The formulations are derived consistently based on sound thermodynamic principles.
The paper presents an approach to constitutive modelling of concrete using damage mechanics and plasticity theory. The thermodynamic formulation, and parameter identification of a non-local coupled damage-plasticity model are presented in this study. The particular focus is the calibration of model parameters. It is shown that both the local parameters and the parameters governing the non-local interaction can be determined from experimental data reliably and consistently. A novel procedure is developed for parameter identification, using the separation of total dissipation energy into additive parts corresponding to different dissipation mechanisms. The relationship between the local and non-local parameters is also addressed, helping to obtain model responses consistent with the fracture energy of the material. The application of the model and the calibration procedure proposed in this study to the numerical failure analysis of concrete structures is illustrated through a series of real structural tests, showing both the performance of the model and the consistency of the proposed calibration procedure.
A Tensile Plastic Damage Constitutive Model of Concrete Based on Energy
Based on the theory of damage mechanics, continuum mechanics and irreversible thermodynamics, considering the coupling relation of plastic stain and damage, the certain function relation is supposed between the plastic free energy and the elastic free energy, so the damage energy release rate is defined. According to the Weibull distribution curve, the relationship between the damage variable and the energy release rate is established, thus the concrete tensile damage evolution equation is deduced. Finally, based on the plastic characteristics of concrete under the action of tensile load, the empirical formula of plastic deformation is obtained. Therefore, the tensile plastic damage constitutive model of concrete is established. The uniaxial tension test results and engineering examples are used for verification of the effectiveness and applicability of this model. Analysis results show that the tensile plasticity constitutive model can more truly reflect the concrete tensile damage evolution process.
Anisotropic damageplasticity model for concrete
International Journal of Plasticity, 2008
International Journal of Plasticity journal homepage: www.elsevier.com/locate/ijplas is an essential yet challenging task for standard civil engineering applications, not to mention complex concrete structures that require further understanding in terms of the prediction of failure patterns. The distinctive behavior of concrete under tensile or compressive loading has also increased the complexity of the constitutive modeling of its behavior (see ).
Elastic Plastic and Damage Model for Concrete Materials: Part I - Theoretical Formulation
A thermodynamically consistent macroscopic constitutive model for concrete that incorporates concrete effective stress space plasticity and fracture energy based - continuum damage mechanics is presented. A plasticity yield criterion, with multiple hardening functions and a non-associative plastic flow rule, is used simultaneously with two (tensile and compressive) isotropic damage criteria. The spectral decomposition of the stress tensor into tensile and compressive components is utilized in all criteria in order to simulate different responses of the material under various loading patterns. The damage criteria are based on the hydrostatic- deviatoric sensitive damage energy release rates in tension and compression derived from the Helmholtz free energy function. Three dissipation mechanisms are defined, one for plasticity and two for damage, to control the dissipation process in the material model. The consistent elastic-plastic-damage tangent operator is also derived, which concl...
2009
A thermodynamically consistent macroscopic constitutive model for concrete that incorporates concrete effective stress space plasticity and fracture energy based-continuum damage mechanics is presented. A plasticity yield criterion, with multiple hardening functions and a non-associative plastic flow rule, is used simultaneously with two (tensile and compressive) isotropic damage criteria. The spectral decomposition of the stress tensor into tensile and compressive components is utilized in all criteria in order to simulate different responses of the material under various loading patterns. The damage criteria are based on the hydrostaticdeviatoric sensitive damage energy release rates in tension and compression derived from the Helmholtz free energy function. Three dissipation mechanisms are defined, one for plasticity and two for damage, to control the dissipation process in the material model. The consistent elastic-plastic-damage tangent operator is also derived, which concludes the theoretical formulation of the proposed model. Verification examples are provided in order to evaluate the ability of the proposed model to capture the behavior of concrete under different states of loading. The detailed scheme of numerical integration of the constitutive equations and the application of the proposed model to study concrete and reinforced concrete members are important issues discussed in part II of this work
Proceedings of the Proceedings of the 1st International Multi-Disciplinary Conference Theme: Sustainable Development and Smart Planning, IMDC-SDSP 2020, Cyperspace, 28-30 June 2020
Concrete damage plasticity (CDP) model is used to model the concrete damage through using ABAQUS software. Among several input parameters that should be defined in CDP model, the dilation angle (ψ), eccentricity parameter and tensile behaviour, have been identified as a significant influence on the finite element (FE) results for concrete modelling under static loading while limited studies examined these parameters for concrete subjected to impact load and high-strain rate. This study aims to focus on numerical modelling of impact-loaded concrete, examine and calibrate the above CDP model parameters using three-dimensional FE modelling. Several values of dilation angles, ψ, of 30 to 55 0 and eccentricity parameter of 0.1 to 0.2 have been used to capture the test behaviour. The model tensile softening behaviour was also investigated using three models, bilinear stress-strain, tri-linear stress-strain and stress-crack opening displacement. The FE results revealed that the value of dilation angle ranged 45-50 0 , the eccentricity parameter and tri-linear stress-strain model of tensile softening provided better correlations with test results in terms of displacement-time plots and cracking paths.
A plastic-damage model for concrete under compression
International Journal of Mechanical Sciences, 2019
A phenomenological model for plain concrete under compression is formulated within the framework of the coupled elastoplastic-damage theory. Phenomenological elastoplastic-damage models have been widely used for concrete because of their capability of representing both the permanent inelastic deformations and the degradation of material moduli beyond the elastic range. The essential contribution introduced in this paper is the proposed partitioning of the strain tensor within the coupled elastoplasticdamage framework which simplifies the selection of the failure surface and the potential function. Proposed partitioning permits the use of single failure criterion and single potential surface that are effective for both damage and plasticity models during inelastic deformations. Therefore, the coupled elastoplastic-damage model can be easily calibrated to fit the observed concrete behaviour based on well-established non-associated plasticity rules for concrete. The proposed approach also simplifies the numerical procedure by eliminating iterations that is required to equilibrate the stresses in plastic and damage components of the model. The numerical implementation is explained, and the results predicted by the model are compared with experimental data provided in the literature.
The development of a coupled damage-plasticity constitutive model for concrete is presented. Emphasis is put on thermodynamic admissibility, rigour and consistency both in the formulation of the model, 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 model can be derived from two specified energy potentials, following procedures established beforehand. Based on this framework, a constitutive model featuring full coupling between damage and plasticity in both tension and compression is developed. Tensile and compressive responses of the material are captured using two separate damage criteria, and a yield criterion with a multiple hardening rule. A crucial part of this study is the identification of model parameters, with these all being shown to be identifiable and computable based on standard tests on concrete. Behaviour of the model is assessed against experimental data on concrete.