Articles de revista
http://hdl.handle.net/2117/428
2021-11-27T02:26:51ZPosibilidades de los ordenadores personales en el cálculo de estructuras por el método de los elementos finitos
http://hdl.handle.net/2117/327489
Posibilidades de los ordenadores personales en el cálculo de estructuras por el método de los elementos finitos
Oñate Ibáñez de Navarra, Eugenio; Gaona, Ángel; Oliver Olivella, Xavier; Suárez Arroyo, Benjamín
2020-07-23T11:33:14ZOñate Ibáñez de Navarra, EugenioGaona, ÁngelOliver Olivella, XavierSuárez Arroyo, BenjamínAn accurate nonlocal bonded discrete element method for nonlinear analysis of solids: application to concrete fracture tests
http://hdl.handle.net/2117/192931
An accurate nonlocal bonded discrete element method for nonlinear analysis of solids: application to concrete fracture tests
Celigueta Jordana, Miguel Ángel; Latorre Sánchez, Juan Salvador; Arrufat Garcia, Ferran; Oñate Ibáñez de Navarra, Eugenio
We present a numerical procedure for elastic and nonlinear analysis (including fracture situations) of solid materials and structures using the discrete element method. It can be applied to strongly cohesive frictional materials such as concrete and rocks. The method consists on defining nonlocal constitutive equations at the contact interfaces between discrete particles using the information provided by the stress tensor over the neighbor particles. The method can be used with different yield surfaces, and in the paper, it is applied to the analysis of fracture of concrete samples. Good comparison with experimental results is obtained.
The final publication is available at Springer via http://dx.doi.org/10.1007/s40571-019-00278-5.
2020-07-14T10:34:53ZCeligueta Jordana, Miguel ÁngelLatorre Sánchez, Juan SalvadorArrufat Garcia, FerranOñate Ibáñez de Navarra, EugenioWe present a numerical procedure for elastic and nonlinear analysis (including fracture situations) of solid materials and structures using the discrete element method. It can be applied to strongly cohesive frictional materials such as concrete and rocks. The method consists on defining nonlocal constitutive equations at the contact interfaces between discrete particles using the information provided by the stress tensor over the neighbor particles. The method can be used with different yield surfaces, and in the paper, it is applied to the analysis of fracture of concrete samples. Good comparison with experimental results is obtained.A plastic-damage model for concrete
http://hdl.handle.net/2117/192680
A plastic-damage model for concrete
Lubliner, Jacob; Oliver Olivella, Xavier; Oller Martínez, Sergio Horacio; Oñate Ibáñez de Navarra, Eugenio
In this paper a constitutive model based on an internal variable-formulation of plasticity theory for the non-linear analysis of concrete is presented. The model uses a new yield criterion which matches experimental data quite well and it accounts for both elastic and plastic stiffness degradations effects. Onset and amount of cracking can be studied by a simple postprocessing of the finite-element plasticity solution. The accuracy of the model is checked with some examples of application.
2020-07-08T16:27:44ZLubliner, JacobOliver Olivella, XavierOller Martínez, Sergio HoracioOñate Ibáñez de Navarra, EugenioIn this paper a constitutive model based on an internal variable-formulation of plasticity theory for the non-linear analysis of concrete is presented. The model uses a new yield criterion which matches experimental data quite well and it accounts for both elastic and plastic stiffness degradations effects. Onset and amount of cracking can be studied by a simple postprocessing of the finite-element plasticity solution. The accuracy of the model is checked with some examples of application.A consistent characteristic length for smeared cracking models
http://hdl.handle.net/2117/192677
A consistent characteristic length for smeared cracking models
Oliver Olivella, Xavier
A numerical scheme for crack modelling by means of continuous displacement fields is presented. In two-dimensional problems a crack is modelled as a limiting case of two singular lines (with continuous displacements, but discontinuous displacement gradients across them) which tend to coincide with each other. An analysis of the energy dissipated inside the band bounded by both lines allows one to obtain an expression for the characteristic length as the ratio between the energy dissipated per unit surface area (fracture energy) and the energy dissipated per unit volume (specific energy) at a point. The application of these mathematical expressions to the finite element discretized medium allow one to obtain a general spatial and directional expression for the characteristic length which guarantees the objectivity of the results with respect to the size of the finite element mesh. The numerical results presented show the reliability of the proposed expressions.
This is the peer reviewed version of the following article: [Oliver, J. (1989), A consistent characteristic length for smeared cracking models. Int. J. Numer. Meth. Engng., 28: 461-474. doi:10.1002/nme.1620280214], which has been published in final form at https://onlinelibrary.wiley.com/doi/abs/10.1002/nme.1620280214. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
2020-07-08T16:20:05ZOliver Olivella, XavierA numerical scheme for crack modelling by means of continuous displacement fields is presented. In two-dimensional problems a crack is modelled as a limiting case of two singular lines (with continuous displacements, but discontinuous displacement gradients across them) which tend to coincide with each other. An analysis of the energy dissipated inside the band bounded by both lines allows one to obtain an expression for the characteristic length as the ratio between the energy dissipated per unit surface area (fracture energy) and the energy dissipated per unit volume (specific energy) at a point. The application of these mathematical expressions to the finite element discretized medium allow one to obtain a general spatial and directional expression for the characteristic length which guarantees the objectivity of the results with respect to the size of the finite element mesh. The numerical results presented show the reliability of the proposed expressions.A computational model for progressive cracking in large dams due to the swelling of concrete
http://hdl.handle.net/2117/192673
A computational model for progressive cracking in large dams due to the swelling of concrete
Cervera Ruiz, Miguel; Oliver Segura, José; Herrero, E.; Oñate Ibáñez de Navarra, Eugenio
The paper presents a computational model for the analysis of large concrete gravity dams subjected to severe damage due to internal actions. It has been observed in several operating concrete dams that the combined effects of water intrusion and concrete expansion produce a time-advancing deteriorating process that may endanger the global stability of the construction. The present study was undertaken to simulate numerically the observed phenomena and to enable to predict future developments. Tensile cracking of the concrete is modelled using an elasticfracturing constitutive model. The model is able to simulate in a realistic manner the phenomena of primary and secondary crack initiation, elastic degradation, crack closing and reopening. The triggering of the volumetric expansion due to water intrusion is linked to the onset of cracking at each point, assuming that water enters the dam mostly through the cracks. Temperature and pore-water pressure effects are included using assumed distributions based on available field data. Construction joints are modelled using a frictional joint element, although a “constitutive alternative” is outlined. Close surveillance of the behaviour of a dam that presented this sort of problem was used to calibrate the numerical model and to confirm the obtained results.
2020-07-08T16:10:09ZCervera Ruiz, MiguelOliver Segura, JoséHerrero, E.Oñate Ibáñez de Navarra, EugenioThe paper presents a computational model for the analysis of large concrete gravity dams subjected to severe damage due to internal actions. It has been observed in several operating concrete dams that the combined effects of water intrusion and concrete expansion produce a time-advancing deteriorating process that may endanger the global stability of the construction. The present study was undertaken to simulate numerically the observed phenomena and to enable to predict future developments. Tensile cracking of the concrete is modelled using an elasticfracturing constitutive model. The model is able to simulate in a realistic manner the phenomena of primary and secondary crack initiation, elastic degradation, crack closing and reopening. The triggering of the volumetric expansion due to water intrusion is linked to the onset of cracking at each point, assuming that water enters the dam mostly through the cracks. Temperature and pore-water pressure effects are included using assumed distributions based on available field data. Construction joints are modelled using a frictional joint element, although a “constitutive alternative” is outlined. Close surveillance of the behaviour of a dam that presented this sort of problem was used to calibrate the numerical model and to confirm the obtained results.An analysis of strong discontinuities induced by strain-softening in rate-independent inelastic solids
http://hdl.handle.net/2117/192670
An analysis of strong discontinuities induced by strain-softening in rate-independent inelastic solids
Simó, Juan Carlos; Oliver Olivella, Xavier; Armero, Francisco
Ket qualitative features of solutions exhibiting strong discontinuities in rate-independent inelastic solids are identified and exploited in the design of a new class of finite element approximations. The analysis shows that the softening law must be re-interpreted in a distributional sense for the continuum solutions to make mathematical sense and provides a precise physical interpretation to the softening modulus. These results are verified by numerical simulations employing a regularized discontinuous finite element method which circumvent the strong mesh-dependence exhibited by conventional methods, without resorting to viscosity or introducing additional ad-hoc parameters. The analysis is extended to a new class of anisotropic rate-independent damage models for brittle materials.
The final publication is available at Springer via http://dx.doi.org/10.1007/BF00372173.
2020-07-08T16:02:26ZSimó, Juan CarlosOliver Olivella, XavierArmero, FranciscoKet qualitative features of solutions exhibiting strong discontinuities in rate-independent inelastic solids are identified and exploited in the design of a new class of finite element approximations. The analysis shows that the softening law must be re-interpreted in a distributional sense for the continuum solutions to make mathematical sense and provides a precise physical interpretation to the softening modulus. These results are verified by numerical simulations employing a regularized discontinuous finite element method which circumvent the strong mesh-dependence exhibited by conventional methods, without resorting to viscosity or introducing additional ad-hoc parameters. The analysis is extended to a new class of anisotropic rate-independent damage models for brittle materials.Seismic evaluation of concrete dams via continuum damage models
http://hdl.handle.net/2117/192667
Seismic evaluation of concrete dams via continuum damage models
Cervera Ruiz, Miguel; Oliver Olivella, Xavier; Carvalho Marques de Faria, Rui Manuel
In this paper a general methodology for the analysis of large concrete dams subjected to seismic excitation is outlined. It is valid both for gravity dams (2D representation) and arch dams (3D representation). The method allows for non-linear material behaviour of the dam, ‘transparent fictitious boundaries’ for dealing properly with in-coming and out-going seismic waves, and an efficient procedure to deal with dam-soil-fluid interaction. The mechanical behaviour of concrete is modelled using an isotropic damage model which allows for tension and compression damage, and exhibits stiffness recovery upon load reversals. Emphasis is placed in the treatment of fluid-structure interaction, regarding both formulation and efficiency aspects. A gravity dam and an arch dam are analysed subjected to artificially generated earthquakes of different intensities, and the results are used to study the degree of (un)safety of the dams.
This is the peer reviewed version of the following article: [Cervera, M., Oliver, J. and Faria, R. (1995), Seismic evaluation of concrete dams via continuum damage models. Earthquake Engng. Struct. Dyn., 24: 1225-1245. doi:10.1002/eqe.4290240905], which has been published in final form at https://onlinelibrary.wiley.com/doi/abs/10.1002/eqe.4290240905. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
2020-07-08T15:48:38ZCervera Ruiz, MiguelOliver Olivella, XavierCarvalho Marques de Faria, Rui ManuelIn this paper a general methodology for the analysis of large concrete dams subjected to seismic excitation is outlined. It is valid both for gravity dams (2D representation) and arch dams (3D representation). The method allows for non-linear material behaviour of the dam, ‘transparent fictitious boundaries’ for dealing properly with in-coming and out-going seismic waves, and an efficient procedure to deal with dam-soil-fluid interaction. The mechanical behaviour of concrete is modelled using an isotropic damage model which allows for tension and compression damage, and exhibits stiffness recovery upon load reversals. Emphasis is placed in the treatment of fluid-structure interaction, regarding both formulation and efficiency aspects. A gravity dam and an arch dam are analysed subjected to artificially generated earthquakes of different intensities, and the results are used to study the degree of (un)safety of the dams.A rate-dependent isotropic damage model for the seismic analysis of concrete dams
http://hdl.handle.net/2117/192663
A rate-dependent isotropic damage model for the seismic analysis of concrete dams
Cervera Ruiz, Miguel; Oliver Olivella, Xavier; Manzoli, Osvaldo
In this paper a rate-dependent isotropic damage model developed for the numerical analysis of concrete dams subjected to seismic excitation is presented. The model is shown to incorporate two features essential for seismic analysis: stiffness degradation and stiffness recovery upon load reversals and strain-rate sensitivity. The issue of mesh objectivity is addressed using the concept of the ‘characteristic length’ of the fracture zone, to show that both the softening modulus and the fluidity parameter must depend on it to provide consistent results as the computational mesh is refined. Some aspects of the numerical implementation of the model are also treated, to show that the model can be easily incorporated in any standard non-linear finite element code. The application of the proposed model to the seismic analysis of a large gravity concrete dam shows that the structural response may vary significantly in terms of the development of damage. The inclusion of rate sensitivity is able to reproduce the experimental observation that the tensile peak strength of concrete can be increased up to 50 percent for the range of strain rates that appear in a structural safety analysis of a dam subjected to severe seismic actions.
This is the peer reviewed version of the following article: [CERVERA, M., OLIVER, J. and MANZOLI, O. (1996), A RATE‐DEPENDENT ISOTROPIC DAMAGE MODEL FOR THE SEISMIC ANALYSIS OF CONCRETE DAMS. Earthquake Engng. Struct. Dyn., 25: 987-1010. doi:10.1002/(SICI)1096-9845(199609)25:9<987::AID-EQE599>3.0.CO;2-X], which has been published in final form at https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291096-9845%28199609%2925%3A9%3C987%3A%3AAID-EQE599%3E3.0.CO%3B2-X. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."
2020-07-08T15:32:56ZCervera Ruiz, MiguelOliver Olivella, XavierManzoli, OsvaldoIn this paper a rate-dependent isotropic damage model developed for the numerical analysis of concrete dams subjected to seismic excitation is presented. The model is shown to incorporate two features essential for seismic analysis: stiffness degradation and stiffness recovery upon load reversals and strain-rate sensitivity. The issue of mesh objectivity is addressed using the concept of the ‘characteristic length’ of the fracture zone, to show that both the softening modulus and the fluidity parameter must depend on it to provide consistent results as the computational mesh is refined. Some aspects of the numerical implementation of the model are also treated, to show that the model can be easily incorporated in any standard non-linear finite element code. The application of the proposed model to the seismic analysis of a large gravity concrete dam shows that the structural response may vary significantly in terms of the development of damage. The inclusion of rate sensitivity is able to reproduce the experimental observation that the tensile peak strength of concrete can be increased up to 50 percent for the range of strain rates that appear in a structural safety analysis of a dam subjected to severe seismic actions.A plasticity model for simulation of industrial powder compaction processes
http://hdl.handle.net/2117/192660
A plasticity model for simulation of industrial powder compaction processes
Oliver Olivella, Xavier; Oller Martínez, Sergio Horacio; Cante Terán, Juan Carlos
A constitutive model, based on large strain plasticity, for simulation of industrial powder compaction processes is presented. The elastic response is stated in terms of a hyperelastic model based on a hookean elastic free energy. Plastic response is defined in terms of a two parameter yield surface that evolves in terms of the relative density. Two different flow rules are considered and tested in front of some available experimental results. Application to the simulation of an actual powder-metallurgy compaction process is also shown.
2020-07-08T15:22:23ZOliver Olivella, XavierOller Martínez, Sergio HoracioCante Terán, Juan CarlosA constitutive model, based on large strain plasticity, for simulation of industrial powder compaction processes is presented. The elastic response is stated in terms of a hyperelastic model based on a hookean elastic free energy. Plastic response is defined in terms of a two parameter yield surface that evolves in terms of the relative density. Two different flow rules are considered and tested in front of some available experimental results. Application to the simulation of an actual powder-metallurgy compaction process is also shown.A strain-based plastic viscous-damage model for massive concrete structures
http://hdl.handle.net/2117/192659
A strain-based plastic viscous-damage model for massive concrete structures
Faria, R; Oliver Olivella, Xavier; Cervera Ruiz, Miguel
Within the framework of continuum damage mechanics, a new constitutive damage model for massive concrete is presented, mainly intended for the seismic analysis of gravity and arch dams. Consistent with thermodynamic requirements, a straindriven formalism is adopted, improving the algorithmic efficiency as much as required for the analysis of large scale problems to become feasible. Two scalar damage variables are introduced as internal variables, as well as a plastic-strain tensor. An extension to account for the concrete strain-rate dependency, suitable for seismic analysis, is presented at the end. The efficiency of numerical predictions from the constitutive model is illustrated through numerical applications and algorithmic implementation is also detailed.
2020-07-08T15:12:48ZFaria, ROliver Olivella, XavierCervera Ruiz, MiguelWithin the framework of continuum damage mechanics, a new constitutive damage model for massive concrete is presented, mainly intended for the seismic analysis of gravity and arch dams. Consistent with thermodynamic requirements, a straindriven formalism is adopted, improving the algorithmic efficiency as much as required for the analysis of large scale problems to become feasible. Two scalar damage variables are introduced as internal variables, as well as a plastic-strain tensor. An extension to account for the concrete strain-rate dependency, suitable for seismic analysis, is presented at the end. The efficiency of numerical predictions from the constitutive model is illustrated through numerical applications and algorithmic implementation is also detailed.