Size Effect in Brazilian Split-Cylinder Tests: Measurements and Fracture Analysis
ACI Materials Journal, 1991
Size effect in split-cylinder (Brazilian) tensile tests is studied experimentally and analyzed th... more Size effect in split-cylinder (Brazilian) tensile tests is studied experimentally and analyzed theoretically. Tests of a very broad size range, 1:26, were conducted on cylindrical disks of a constant thickness made from concrete with aggregate of a maximum 5-mm size. The ...
ABSTRACT Among the “theories” applied to model concrete behavior, damage mechanics has proven to ... more ABSTRACT Among the “theories” applied to model concrete behavior, damage mechanics has proven to be efficient. One of the first models for concrete introduced within such a framework is Mazars’ damage model. A new formulation of such a model, called the “μ model”, is proposed herein for the purpose of 3D cyclic and dynamic loading, based on a coupling of elasticity and damage within an isotropic formulation. Unilateral behavior (i.e. the opening and closure of cracks) is introduced by the use of two thermodynamic variables. A threshold surface is then associated with each of these variables and strain rate acts on the initial threshold. Applications are presented on plain or reinforced concrete elements subjected to various loading (uni- and multi-axial, cyclic, dynamic). A comparison with experimental results demonstrates the effectiveness of the various selected options.
International Journal of Solids and Structures, 1996
Abstracl-Fracture mechanics and damage mechanics are two correlated theories. In some instances, ... more Abstracl-Fracture mechanics and damage mechanics are two correlated theories. In some instances, e.g., for large specimens, crack propagation may be viewed equivalently as a sudden localization of damage. Relationships based on thermodynamic considerations between the two theories are presented in this paper. They lead to the definition of the equivalent crack concept, in passing from a damage zone to a fracture problem and, conversely, a damage zone is determined which is equivalent to a crack. Different possible applications are presented showing that, for the same problem, the two concepts can be used depending on the situation. Furthermore a solution to calculate fracture energy for large specimens, when damage parameters deduced from classical tests are known, is proposed to illustrate the capability of these equivalences. Copyright 0 1996 Elsevier Science Ltd.
Bifurcations, Instabilities, Degradation in Geomechanics, 2007
The non linear behaviour of concrete is often simulated using local constitutive models based on ... more The non linear behaviour of concrete is often simulated using local constitutive models based on the continuous damage mechanics theory. This approach however is not adequate for post-localisation studies with strain softening. It is well known that spurious mesh dependence appears in computations and cases of failure without energy dissipation. In order to improve computational performance second grade local models are chosen to include a meso scale in the continuous damage model. This approach differs from the nonlocal one in the sense that it is a local theory with higher order stresses depending only on the local cinematic history. 1D numerical computations with concrete specimens are presented. Using a random initialisation of the iterative solver of the equilibrium equation we search the existence of various solutions for the boundary value study and also to see if the second grade term regularise the problem giving results that are mesh insensitive and objective.
Size Effect in Brazilian Split-Cylinder Tests: Measurements and Fracture Analysis
ACI Materials Journal, 1991
Size effect in split-cylinder (Brazilian) tensile tests is studied experimentally and analyzed th... more Size effect in split-cylinder (Brazilian) tensile tests is studied experimentally and analyzed theoretically. Tests of a very broad size range, 1:26, were conducted on cylindrical disks of a constant thickness made from concrete with aggregate of a maximum 5-mm size. The ...
ABSTRACT Among the “theories” applied to model concrete behavior, damage mechanics has proven to ... more ABSTRACT Among the “theories” applied to model concrete behavior, damage mechanics has proven to be efficient. One of the first models for concrete introduced within such a framework is Mazars’ damage model. A new formulation of such a model, called the “μ model”, is proposed herein for the purpose of 3D cyclic and dynamic loading, based on a coupling of elasticity and damage within an isotropic formulation. Unilateral behavior (i.e. the opening and closure of cracks) is introduced by the use of two thermodynamic variables. A threshold surface is then associated with each of these variables and strain rate acts on the initial threshold. Applications are presented on plain or reinforced concrete elements subjected to various loading (uni- and multi-axial, cyclic, dynamic). A comparison with experimental results demonstrates the effectiveness of the various selected options.
International Journal of Solids and Structures, 1996
Abstracl-Fracture mechanics and damage mechanics are two correlated theories. In some instances, ... more Abstracl-Fracture mechanics and damage mechanics are two correlated theories. In some instances, e.g., for large specimens, crack propagation may be viewed equivalently as a sudden localization of damage. Relationships based on thermodynamic considerations between the two theories are presented in this paper. They lead to the definition of the equivalent crack concept, in passing from a damage zone to a fracture problem and, conversely, a damage zone is determined which is equivalent to a crack. Different possible applications are presented showing that, for the same problem, the two concepts can be used depending on the situation. Furthermore a solution to calculate fracture energy for large specimens, when damage parameters deduced from classical tests are known, is proposed to illustrate the capability of these equivalences. Copyright 0 1996 Elsevier Science Ltd.
Bifurcations, Instabilities, Degradation in Geomechanics, 2007
The non linear behaviour of concrete is often simulated using local constitutive models based on ... more The non linear behaviour of concrete is often simulated using local constitutive models based on the continuous damage mechanics theory. This approach however is not adequate for post-localisation studies with strain softening. It is well known that spurious mesh dependence appears in computations and cases of failure without energy dissipation. In order to improve computational performance second grade local models are chosen to include a meso scale in the continuous damage model. This approach differs from the nonlocal one in the sense that it is a local theory with higher order stresses depending only on the local cinematic history. 1D numerical computations with concrete specimens are presented. Using a random initialisation of the iterative solver of the equilibrium equation we search the existence of various solutions for the boundary value study and also to see if the second grade term regularise the problem giving results that are mesh insensitive and objective.
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Papers by J. Mazars