Employment of damage plasticity constitutive model for concrete members subjected to high strain-rate (original) (raw)
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Calibration of a New Concrete Damage Plasticity Theoretical Model Based on Experimental Parameters
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The introduction of concrete damage plasticity material models has significantly improved the accuracy with which the concrete structural elements can be predicted in terms of their structural response. Research into this method's accuracy in analyzing complex concrete forms has been limited. A damage model combined with a plasticity model, based on continuum damage mechanics, is recommended for effectively predicting and simulating concrete behaviour. The damage parameters, such as compressive and tensile damages, can be defined to simulate concrete behavior in a damaged-plasticity model accurately. This research aims to propose an analytical model for assessing concrete compressive damage based on stiffness deterioration. The proposed method can determine the damage variables at the start of the loading process, and this variable continues to increase as the load progresses until complete failure. The results obtained using this method were assessed through previous studies, w...
Improvement and Enhancement of Concrete Damage Plasticity Model
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Abstract: The purpose of this paper is to make an improved concrete damage plasticity model that focus on a post cracking behavior. First, we constitute the material model that simulates a process of closing the large tensile cracks and recovering the compression stiffness. Second, the model is enhanced by adding another feature that simulates a transition from compression to tension again. Finally, experimental simulation analyses are conducted for validation of efficiency.
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MATEC Web of Conferences
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A plasticity and anisotropic damage model for plain concrete
International Journal of Plasticity, 2007
A plastic-damage constitutive model for plain concrete is developed in this work. Anisotropic damage with a plasticity yield criterion and a damage criterion are introduced to be able to adequately describe the plastic and damage behavior of concrete. Moreover, in order to account for different effects under tensile and compressive loadings, two damage criteria are used: one for compression and a second for tension such that the total stress is decomposed into tensile and compressive components. Stiffness recovery caused by crack opening/closing is also incorporated. The strain equivalence hypothesis is used in deriving the constitutive equations such that the strains in the effective (undamaged) and damaged configurations are set equal. This leads to a decoupled algorithm for the effective stress computation and the damage evolution. It is also shown that the proposed constitutive relations comply with the laws of thermodynamics. A detailed numerical algorithm is coded using the user subroutine UMAT and then implemented in the advanced finite element program ABAQUS. The numerical simulations are shown for uniaxial and biaxial tension and compression. The results show very good correlation with the experimental data.
Damage Model for Normal & High Strength Concrete
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An anisotropic damage model capable of predicting the response of normal and high strength concretes is presented in this study. The model utilizes a concrete appropriate effective compliance matrix in constructing the constitutive equations. Three parameters α, β and γ were used in the effective compliance matrix. α and β are introduced to model the different behaviour of concrete in tension and compression while the third parameter γ was introduced to account for volumetric change. The concept of multiple surfaces i.e. limit fracture surface, loading function surface and bounding surface, defined in strain-energy release space, is used to define the evolution of damage. After calibration for various strengths of concrete, ranging from 27.6 MPa to 120 MPa, the predictive capability of the proposed elasto-damage model for uniaxial and biaxial stress paths was investigated for uniaxial compression, biaxial compression, uniaxial tension and tension-compression. The simulative capabili...
Survey of four damage models for concrete
2009
Four conventional damage plasticity models for concrete, the Karagozian and Case model (K&C), the Riedel-Hiermaier-Thoma model (RHT), the Brannon-Fossum model (BF1), and the Continuous Surface Cap Model (CSCM) are compared. The K&C and RHT models have been used in commercial finite element programs many years, whereas the BF1 and CSCM models are relatively new. All four models are essentially isotropic plasticity models for which "plasticity" is regarded as any form of inelasticity. All of the models support nonlinear elasticity, but with different formulations. All four models employ three shear strength surfaces. The "yield surface" bounds an evolving set of elastically obtainable stress states. The "limit surface" bounds stress states that can be reached by any means (elastic or plastic). To model softening, it is recognized that some stress states might be reached once, but, because of irreversible damage, might not be achievable again. In other words, softening is the process of collapse of the limit surface, ultimately down to a final "residual surface" for fully failed material. The four models being compared differ in their softening evolution equations, as well as in their equations used to degrade the elastic stiffness. For all four models, the strength surfaces are cast in stress space. For all four models, it is recognized that scale effects are important for softening, but the models differ significantly in their approaches. The K&C documentation, for example, mentions that a particular material parameter
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
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.
F IDENTIFICATION OF PARAMETERS OF CONCRETE DAMAGE PLASTICITY CONSTITUTIVE MODEL
The paper presents a method and requiremens of the material parameters identification for concrete damage plasticity constitutive model. The laboratory tests, which are necessary to identify constitutive parameters of this model have been presented. Two standard applications have been shown that test the constitutive model of the concrete. The first one is the analysis of the three-point bending single-edge notched conrete beam specimen. The second presents the four-point bending single-edge notched conrete beam specimen under static loadings.
Plasticity-Damage Model for Concrete under Cyclic Multiaxial Loading
Journal of Engineering Mechanics-asce, 1993
A model that combines plasticity and damage mechanics is developed to assess both multiaxial monotonic and cyclic behavior of concrete. The model adopts a bounding surface concept and combines plastic deformation with the deformation due to damage. Plastic strain components are calculated by using the plastic modulus that is a function of the distance from the current stress point to the bounding surface along the deviatoric stress direction S o. Similarly, damage growth rate is obtained by the hardening modulus, which is a function of the distance just defined. The hardening behavior of concrete is assumed herein to be controlled by both damage and plasticity, while the strain-softening regime is controlled by damage processes only. The simultaneous use of the plasticity surface and the damage surface, leads to a constitutive model that accounts for the essential features of concrete such as pressure sensitivity, shear compaction-dilatancy, stiffness degradation, and softening behavior.