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• Simulación por ordenador del comportamiento resistente de estructuras: El laboratorio virtual de estructuras

  E. Oñate, A. Hanganu, J. Miquel, B. Suárez

  (2000). Research Report, Nº PI193

  
  

  Abstract

  Se presenta el concepto de Laboratorio Virtual de Estructuras (LAVE) para evaluar por ordenador la capacidad resistente de estructuras de hormigón y el coeficiente de seguridad al colapso utilizando modelos de cálculo no lineal basados en la teoría del daño y el método de elementos finitos. Se describen diversos ejemplos de aplicación del LAVE al análisis de la resistencia última de estructuras de hormigón en masa y armado.   

  Abstract
  Se presenta el concepto de Laboratorio Virtual de Estructuras (LAVE) para evaluar por ordenador la capacidad resistente de estructuras de hormigón y el coeficiente [...]

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• Del ábaco de fichas a Internet

  E. Oñate

  (2000). Research Report, Nº PI194

  
  

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• The braid of numbers

  E. Oñate

  (2000). Research Report, Nº PI195

  
  

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• Meshless analysis of incompressible flows using the Finite Point Method

  E. Oñate, C. Sacco, S. Idelsohn

  (2000). Research Report, Nº PI196

  
  

  Abstract

  A stabilized finite point method (FPM) for meshless analysis of incompressible fluid flows is presented. The stabilization approach is based in the finite calculus (FIC) procedure. An enhanced fractional step procedure allowing the semi-implicit numerical solution of incompressible fluids using the PFM is described. Examples of application of the stabilized FPM to the solution of incompressible flows problems are presented.

  Abstract
  A stabilized finite point method (FPM) for meshless analysis of incompressible fluid flows is presented. The stabilization approach is based in the finite calculus (FIC) procedure. [...]

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• Stabilized finite element approximation of transient incompressible flows using orthogonal subscales

  R. Codina

  (2000). Research Report, Nº PI197

  
  

  Abstract

  In this paper we present a stabilized finite element method to solve the transient Navier-Stokes equations based on the decomposition of the unknowns into resolvable and sub grid scales. The latter are approximately accounted for, so as to end up with a stable finite element problem which, in particular, allows to deal with convection-dominated flows and the use of equal velocity-pressure interpolations. Three main issues are addressed. The first is a method to estimate the behavior of the stabilization parameters based on a Fourier analysis of the problem for the subscales. Secondly, the way to deal with transient problems discretized using a finite difference scheme is discussed. Finally, the treatment of the nonlinear term is also analyzed. A very important feature of this work is that the sub grid scales are taken as orthogonal to the finite element space. In the transient case, this simplifies considerably the numerical scheme.  

  Abstract
  In this paper we present a stabilized finite element method to solve the transient Navier-Stokes equations based on the decomposition of the unknowns into resolvable and sub [...]

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• On isotropic scalar damage models for the numerical analysis of concrete structures

  R. Faria, J. Oliver, M. Cervera

  (2000). Research Report, Nº PI198

  
  

  Abstract

  Within the framework of Continuum Damage Mechanics some isotropic scalar damage models for concrete are revisited, with emphasis on a recent one proposed by the authors. This scalar damage model is based on the assumption that a stress split is required to capture unilateral behaviour exhibited by concrete when passing from tension to compression. Similar assumptions are pursued on many scalar damage models, yet with many differences being encountered on the strategies adopted for the implementation of such split, which sometimes is performed over the strain tensor. In this paper a discussion on the implications of those splits is conducted, as well as on the norms that define the elastic domain in the stress space. For the proposed damage model a strain-driven formalism is adopted, but the stress split is performed on the effective elastic stress tensor, which is shown to correspond to a split of the Cauchy stress tensor. This strategy improves the algorithmic efficiency as much as required for the seismic analysis of large-scale problems, and circumvents many of the drawbacks present in similar damage models. Besides, two scalar damage variable are introduced as internal variables, as well as an inelastic strain tensor. Efficiency of the proposed constitutive model is illustrated through numerical applications. Algorithmic implementation is also detailed.

  Abstract
  Within the framework of Continuum Damage Mechanics some isotropic scalar damage models for concrete are revisited, with emphasis on a recent one proposed by the authors. This [...]

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• Interface GiD-SAP90 elemento ASOLID

  J. Maristany, F. Salinas, A. Mestre

  (2000). Research Report, Nº PI199

  
  

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• Desarrollos y aplicaciones de modelos de fractura en la escuela de ingenieros de caminos de Barcelona

  E. Oñate

  (2000). Research Report, Nº PI201

  
  

  Abstract

  El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos en la Escuela de Ingenieros de Caminos de Barcelona (EICB) durante los últimos quince para el análisis no lineal de estructuras. La motivación fundamental para el desarrollo de estos modelos se centra en el análisis de la seguridad de estructuras de hormigón en masa y armado. La mayor parte de los modelos se basan en la teoría de daño continuo y utilizan el método de los elementos finitos para la solución numérica. Los modelos de daño se han extendido y aplicado también con éxito el análisis de diversas estructuras de edificios históricos. Los desarrollos más recientes de estos modelos en la EICB incluyen la predicción de fenómenos de localización en estructuras de hormigón y el análisis del comportamiento no lineal de estructuras con materiales compuestos. De todos estos modelos se presentan en el artículo unas breves pinceladas, las aplicaciones más relevantes y las referencias donde pueden encontrarse los detalles de cada caso.   

  Abstract
  El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos [...]

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• A finite point method for elasticity problems

  E. Oñate, F. Perazzo, J. Canet

  (2001). Research Report, Nº PI202

  
  

  Abstract

  The basis of the finite point method (FPM) for the fully meshless solution of elasticity problems in structural mechanics is described. A stabilization technique based on a finite calculus procedure is used to improve the quality of the numerical solution. The efficiency and accuracy of the stabilized FPM in the meshless analysis of simple linear elastic structural problems is shown in some examples of applications.

  Abstract
  The basis of the finite point method (FPM) for the fully meshless solution of elasticity problems in structural mechanics is described. A stabilization [...]

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• Finite element analysis of membrane structures

  R. Taylor

  (2001). Research Report, Nº PI203

  
  

  Abstract

  This report summarizes the formulation for a large displacement formulation of a membrance composed of three-node triangular elements. A formulation in terms of the deformation gradient is first constructed in terms of nodal variables. In particular, the use of the right Caunchy-Green deformation tensor is shown to lead to a particulary simple representation in terms of nodal quantities. This may then be used to construct general models for use in static and transient analyses.

  Abstract
  This report summarizes the formulation for a large displacement formulation of a membrance composed of three-node triangular elements. A formulation in terms of the deformation [...]

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