G. Etse - Academia.edu (original) (raw)

Papers by G. Etse

Mecánica Computacional, 2003

Mecánica Computacional, 1996

Las particularidades de Is tearla micropolar continua propuesta por los hermanos Cosserat as anal... more Las particularidades de Is tearla micropolar continua propuesta por los hermanos Cosserat as analizada en .el caso de flexion plana elastica lineal y comparadas con las soluciones de la teoria chlsica del continuo. Los resultados muestran Ia importancia de !os parametros adicionales del continuo de Cosserat en la prediccion del campo de los desplazamientos.

En el presente trabajo se presenta el analisis analitico y geometrico de localizacion de deformac... more En el presente trabajo se presenta el analisis analitico y geometrico de localizacion de deformaciones plasticas en modelos de plasticidad regularizada mediante teoria de gradientes. A partir del metodo geometrico de localizacion, basado en la solucion analitica de la singularidad del tensor de localizacion, se determinan los parametros criticos de falla discontinua para diferentes estados tensionales. Se aplica al modelo material de von Mises. La representacion geometrica de la condicion de localizacion en las coordenadas de tensiones de Mohr, demuestra claramente las ventajas de la formulacion de gradientes en lo que respecta a su capacidad regularizante.

Recent Advances on Green Concrete for Structural Purposes, 2017

This chapter introduces some of the relevant modelling approaches that are being used to simulate... more This chapter introduces some of the relevant modelling approaches that are being used to simulate the behaviour of cementitious materials reinforced with discrete fibres. The major part of these approaches were originally proposed for modelling non-fibrous reinforced cement based materials‚ therefore the main focus herein given is related to the aspects how fibre reinforcement mechanisms have been considered. These approaches were grouped in two classes‚ one where fibres are explicitly considered in the finite element mesh (FEMesh)‚ herein designated as Discrete Fibre Reinforcement Approaches (DFRAs). The other class is designated by smeared fibre reinforcement approaches (SFRAs)‚ where fibres are not part of the FEMesh and their contribution is basically considered attributing a constitutive law to the FRC that simulates the fibre reinforcement mechanisms in terms of the fracture modes of this composite material.

This paper aims at a thorough characterization of the self-healing capacity of cementitious compo... more This paper aims at a thorough characterization of the self-healing capacity of cementitious composites, i.e. their capacity to completely or partially re-seal cracks and, in case, also exhibit recovery of mechanical properties. This problem will be investigated through both experiments and modeling with reference of a normal strength concrete under different types of exposure: i.e., air exposure and water immersion. The effects of the self-healing phenomena on the recovery of stiffness and loadbearing capacity have been evaluated by means of 3-point bending tests performed up to controlled crack opening and up to failure, respectively before and after conditioning. With reference to the modeling issue, an interface fracture based model, formulated and calibrated by the second and fourth author for the description of fracture processes in concrete, has been herein extended to include the effects of crack healing, through suitably defined functions which affect the time evolution of m...

Computers & Structures, 2017

A damage-plasticity constitutive theory for zero-thickness interfaces is presented aimed at predi... more A damage-plasticity constitutive theory for zero-thickness interfaces is presented aimed at predicting time-dependent self-healing phenomena in concrete. The material model is based on fracture-energy concepts and accounts for the time evolution of concrete porosity induced by the self-healing mechanism. The accuracy and soundness of the proposed interface model are demonstrated through comparative analyses of model predictions against experimental results on three point beam tests performed up to crack opening and then, up to complete failure, before and after been subjected to different exposure conditions, respectively. A wide range of experimental tests was considered in this work for both calibration and validation purposes of the proposed interface model.

Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures, 2016

In this work, the failure behavior of concrete exposed to elevated temperatures is analyzed. A th... more In this work, the failure behavior of concrete exposed to elevated temperatures is analyzed. A thermo-mechanical and poropressure-based interface model for failure analysis of concrete subjected to high temperature is presented. The model represents an extension of a fracture energy-based interface formulation to account for the damage induced by high temperatures and for the temperature dependent pore pressure and humidity in concrete. Thereby, the non-linear response of the proposed coupled thermo-mechanical interface model for porous materials like concrete is activated under kinematic and/or temperature and/or hydraulic increments (with or without jumps). A simplified procedure is proposed to account for the temperature dependent pore pressure in concrete. This contribution focuses on both the formulation of the novel interface constitutive theory and on the strategy proposed for mesoscopic finite element analysis of concrete failure behavior under different hydro-thermo-mechanical conditions. Finally, some numerical analysis are presented which demonstrated the predictive capabilities of the proposed interface model.

CRC Press eBooks, May 2, 2022

In this work, the efficacy and efficiency of a discretization technique based on virtual elements... more In this work, the efficacy and efficiency of a discretization technique based on virtual elements (VEs) and non-linear interface elements (IEs) are assessed for the modelling of representative boundary value problems (BVPs) of fracture processes in concrete components characterized by tortuous crack propagations. In particular, the efficiency of randomness in mesh refinement is evaluated for meshes comprising polyhedral VEs. The results demonstrate the limitations of structured meshes and the effectiveness of random polyhedral virtual meshes in modelling the tortuous propagation of cracks in concrete subjected to mode II fracture, or shear. It is concluded that random h refinement applied to polyhedral meshes allows a statistically accurate prediction of the crack path. In particular, the influence of random mesh generation is studied. The results demonstrate that the average predictions generated by a series of random coarse mesh perturbations of polyhedral elements are very accurate, particularly in terms of peak load and crack path. Finally, an adaptative refinement technique is discussed as a possible technique for efficient identification of the localization zones.

El analisis material a nivel micromecanico constituye uno de los metodos realista para reproducir... more El analisis material a nivel micromecanico constituye uno de los metodos realista para reproducir el comportamiento de algunos materiales, en particular ha sido altamente satisfactorio en materiales cuasifragiles. Por otro lado este camino de analisis tambien es aplicable a huesos. Fundamentalmente los resultados de este tipo analisis pueden utilizarse para la calibracion de modelos continuos a traves de los cuales se desarrollan simulaciones numericas realistas de hueso. En este trabajo se presenta los resultados preliminares de una investigacion enfocada a la simulacion computacional del comportamiento no lineal de huesos. Se presenta un analisis micromecanico del material con estudios de sensibilidad de los parametros mecanicos elasticos respecto del efecto tamano, la porosidad y su distribucion.

North Carolina Law Review, 1970

This study uses a comparative quantitative method that aims to find the difference in prosocial b... more This study uses a comparative quantitative method that aims to find the difference in prosocial behavior based on sex in college students of Satya Wacana Christian University. There are 120 college students involved in this study as participants which consist of 60 men and 60 women. The sampling techniques in this study use the purposive sampling with the criteria of college students in their late adolescent, 18-22 years old, which actively involved in campus and participate in social activities more than three times in one year. The instruments that are used are arranged by the researcher based on aspects prosocial behavior. The result shows that there is no difference in prosocial behavior between male and female college students with a significance value 0f = 0,85 (p > 0,05) so that the hypothesis in this study is rejected. Besides the sex factor, there are other factors that can influence someone to have prosocial behavior.

As extensively accepted, fiber inclusions lead to significant improvements of post-cracking behav... more As extensively accepted, fiber inclusions lead to significant improvements of post-cracking behavior of mortar composites by bridging cracks and providing resistance to crack opening processes. Typically localized failure modes of plain concrete or other mortar composites may turn quasi-ductile through the addition of steel fibers in cement mortar. In this case, the development of multiple crack patterns lead to strain-hardening/softening processes characterized by relatively large energy absorption prior to fracture localization. From the structural standpoint, fiber reinforced concrete structures (FRCS) exhibit superior ductility not only when subjected to compressive but also to tensile loading. In this work fiber reinforced concrete is analyzed and modeled with two different approaches. On the one hand, a macroscopic continuum (smeared-crack) evaluation based on non-linear microplane theory is presented. Following approaches recently proposed in Pietruszczak and Winnicki (2003) ...

The present paper deals with the numerical analysis of fiber-reinforced concrete (FRC) by using s... more The present paper deals with the numerical analysis of fiber-reinforced concrete (FRC) by using special “interface” elements for modeling the nonlinear fracture behavior under general loading conditions. After a brief overview about the basic features of the numerical model, some experimental results currently available in the scientific literature are considered for its validation. Finally, the capabilities and shortcomings of the proposed model for FRC failure analyses are evaluated.

Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures, 2019

The use of multiscale schemes for computational failure evaluations of composites materials has b... more The use of multiscale schemes for computational failure evaluations of composites materials has become a promising topic for evaluating the complex degradation mechanisms at different scales of observations and to achieve accurate information on the effects of these subscales degradation processes on the macroscopic response behavior. In the framework of standard finite element procedures, both concurrent and semi-concurrent multiscale procedures were considered so far for analyzing failure behavior of quasi-brittle materials. When it comes to composite materials such as concrete, which are characterized by inclusions or aggregates that are strongly heterogeneous with respect to size and geometry, it is absolutely necessary to take into account the mesoscopic scale, since it seriously affects the macroscopic response behavior. However, there are well-founded questions about the capabilities of standard finite element procedures to represent heterogeneous mesoscopic structures such as concrete, because they impose geometric constraints and unrealistic boundary conditions that distort the resulting numerical solutions. In this work a new approach is pursued for mesoscale analysis of concrete failure behavior. This is based on combining Virtual Elements (VE) and interfaces in the framework of the discrete approach. In the first part of this work, the basis of the VE technology and of the considered interface model are outlined. Then, the procedure for concrete-mesoscopic meshing proposed in this work based on combining VEM and non-linear interface elements (IE) is detailed. Finally, numerical analysis are presented involving stress paths and failure behavior that shows the potential and efficiency of the approach based on VE and IE for composite materials like concrete are discussed.

Zeitschrift für angewandte Mathematik und Physik, 2019

In this work, a general thermodynamically consistent theory is proposed for multiscale homogeniza... more In this work, a general thermodynamically consistent theory is proposed for multiscale homogenization procedures of saturated and dissipative porous media involving multiphysical complexities. The proposal allows the formulation of coupled constitutive behavior, including thermo-, hydro- and/or mechanical interaction. The homogenization scheme gives rise to macroscopic material equations characterized by a free energy density fully consistent with the microscopic one. Firstly, the thermodynamically consistent multiscale approach is applied to the general case of thermo-poroplastic materials. Then, the formulation is particularized and thoroughly resolved for the case of thermo-poroelastic materials. It is shown that the resulting macroscopic entropy and entropy vector have additional terms to those obtained in previous works based on different homogenization strategies. Finally, a numerical analysis dealing with multiscale analysis of the temperature-dependent tensile behavior of concrete is presented, whereby the proposed scheme is utilized for the multiscale homogenization process. The results demonstrate the soundness of the proposed multiscale homogenization scheme, and in fact shows good agreement with experimental results in the literature regarding the temperature effect on concrete.

World Cement, 2003

Etse (PhD), Martel and R. Fernandez, Penta Engineering Corp., USA, describe the dynamic analysis ... more Etse (PhD), Martel and R. Fernandez, Penta Engineering Corp., USA, describe the dynamic analysis performed for the design and evaluation of installations with vibration problems.

Explicit solutions for localized failure in the form of spatial discontinuities are presented for... more Explicit solutions for localized failure in the form of spatial discontinuities are presented for an elasto-plastic concrete extended Leon model. Analytic results are derived for a variety of different load conditions. It will be shown that localization can not be observed with load histories which are normally traced in conventional triaxial compression tests, while spatial discontinuities might develop during the conventional triaxial extension tests in the form of localized failure. On the other hand, the degenerate load histories in plane strain and, in particular, in plane stress will be shown to be far more critical for localization.