JOURNALS

Documents published in Scipedia

• Mindlin finite strip and axisymmetric finite element shell analysis

  E. Oñate, B. Suárez, E. Hinton

  (1984). Finite Elements Software for Plates and Shells, Hinton E. y Owen D.R.J. (Eds.), Pineridge Press, 1984

  
  

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• Stress, strain and energy splittings for anisotropic elastic solids under volumetric constraints

  C. Felippa, E. Oñate

  (2002). Research Report, Nº PI217

  
  

  Abstract

  We define stress and strain splittings appropriate to linearly elastic anisotropic materials with volumetric constraints. The treatment includes rigidtropic materials, which develop no strains under a stress pattern that is a null eigenvector of the compliance matrix. This model includes as special case incompressible materials, for which the eigenvector is hydrostatic stress. The main finding is that pressure and volumetric strain must be redefined as effective quantities. Using this idea, an energy decomposition that exactly separates deviatoric and volumetric energy follows.

  Abstract
  We define stress and strain splittings appropriate to linearly elastic anisotropic materials with volumetric constraints. The treatment includes rigidtropic materials, [...]

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• Posibilidades de las nuevas tecnologías de información y comunicaciones en el sector de la construcción

  E. Oñate, J. Marcipar, F. Zárate

  (2003). Research Report, Nº PI221

  
  

  Abstract

  Se presenta una breve panorámica de las posibilidades de las nuevas Tecnologías de la Información y las Comunicaciones en el sector de la construcción. Tras unas reflexiones sobre el valor intrínseco de la información y las comunicaciones, se describe el impacto que está teniendo Internet en los nuevos métodos de trabajo, de comercio, de formación y, en general, de intercambio de información a todos los niveles en las actividades de los técnicos del sector de la construcción. Finalmente se especula sobre las posibilidades de las TIC para generar entornos de trabajo inteligentes que generen y gestionen conocimiento para la solución de problemas prácticos.

  Abstract
  Se presenta una breve panorámica de las posibilidades de las nuevas Tecnologías de la Información y las Comunicaciones en el sector de la construcción. [...]

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• Ship hydrodynamics

  E. Oñate, J. García-Espinosa, S. Idelsohn

  (2003). Research Report, Nº PI222

  
  

  Abstract

  This chapter presents an overview of some computational methods for analysis of ship hydrodynamics problems. Attention is focused on the description of a stabilized finite element formulation derived via a finite calculus procedure. Both arbitrary Lagrangian-Eulerian (ALE) and fully Lagrangian forms are presented. Details of the treatment of the free-surface waves and the interaction between the ship structure and the sea water are also given. Examples of application to a variety of ship hydrodynamics problems are shown.

  Abstract
  This chapter presents an overview of some computational methods for analysis of ship hydrodynamics problems. Attention is focused on the description of a stabilized finite [...]

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• A general stabilized formulation for incompressible fluid flow using finite calculus and the finite element method

  E. Oñate, J. García-Espinosa, G. Bugeda, S. Idelsohn

  (2003). Research Report, Nº PI223

  
  

  Abstract

  We present a general formulation for incompressible fluid flow analysis using the finite element method (FEM). The necessary stabilization for dealing with convective effects and the incompressibility condition are introduced via the so called finite calculus (FIC) method. The extension of the standard eulerian form of the equations to an arbitrary lagrangian-eulerian (ALE) frame adequate for treating fluid-structure interaction problems is presented. The fully lagrangian form is also discussed. Details of an effective mesh updating procedure are presented together with a method for dealing with free surface effects of importance for ship hydrodynamic analysis and many other fluid flow problems. Examples of application of the eulerian, the ALE and the fully lagrangian flow descriptions are presented.

  Abstract
  We present a general formulation for incompressible fluid flow analysis using the finite element method (FEM). The necessary stabilization for dealing with convective effects [...]

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• Nonlinear dynamic analysis of RC Frame under earthquake loading

  H. Kwak, E. Oñate, S. Kim

  (2003). Research Report, Nº PI229

  
  

  Abstract

  Nonlinear dynamic analysis of a reinforced concrete (RC) frame under earthquake loading is performed in this paper on the basis of a hysteretic moment-curvature relation. Unlike previous analytic moment-curvature relations which take into account the flexural deformation only with the perfect-bond assumption, the proposed relation considers the rigid-body-motion due to anchorage slip at the fixed end, which accounts for more than 50% of the total deformation, using an equivalent flexural stiffness. The advantages of the proposed relation, compared with the layered section approach and multi-component model, may be on the easiness in application to a complex structure composed of many element and on the reduction in calculation time and memory space. The use of curved unloading and reloading branches inferred from the stress-strain relation of steel and consideration of the pinching effect caused by axial force made it possible to describe the structural response more exactly. Finally, correlation studies between analytical and experimental results are conducted to establish the applicability of the proposed model to the nonlinear dynamic analysis of RC structures.

  Abstract
  Nonlinear dynamic analysis of a reinforced concrete (RC) frame under earthquake loading is performed in this paper on the basis of a hysteretic moment-curvature relation. [...]

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• Nodally exact Ritz discretizations of 1D diffusion–absorption and Helmholtz equations by variational FIC and modified equation methods

  C. Felippa, E. Oñate

  (2003). Research Report, Nº PI237

  
  

  Abstract

  This article presents the first application of the Finite Calculus (FIC) in a Ritz-FEM variational framework. FIC provides a steplength parametrization of mesh dimensions, which is used to modify the shape functions. This approach is applied to the FEM discretization of the steady-state, one-dimensional, diffusion–absorption and Helmholtz equations. Parametrized linear shape functions are directly inserted into a FIC functional. The resulting Ritz-FIC equations are symmetric and carry a element-level free parameter coming from the function modification process. Both constant- and variable-coefficient cases are studied. It is shown that the parameter can be used to produce nodally exact solutions for the constant coefficient case. The optimal value is found by matching the finite-order modified differential equation (FOMoDE) of the Ritz-FIC equations with the original field equation. The inclusion of the Ritz-FIC models in the context of templates is examined. This inclusion shows that there is an infinite number of nodally exact models for the constant coefficient case. The ingredients of these methods (FIC, Ritz, MoDE and templates) can be extended to multiple dimensions

  Abstract
  This article presents the first application of the Finite Calculus (FIC) in a Ritz-FEM variational framework. FIC provides a steplength parametrization of mesh dimensions, [...]

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• A finite calculus formulation of the level set equation

  S. Idelsohn, E. Oñate, S. Ransau

  (2003). Research Report, Nº PI239

  
  

  Abstract

  A finite calculus formulation of the level set equation is presented. Quadratic Galerkin finite elements are used for spatial discretization. A unique stabilization parameter is computed. A time stabilization parameter allowing the use of the forward Euler scheme with Courant number larger than one is presetend.

  Abstract
  A finite calculus formulation of the level set equation is presented. Quadratic Galerkin finite elements are used for spatial discretization. A unique stabilization parameter [...]

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• Development of local models and their computational implementation for polymer coated steel sheets

  J. Rojek, M. Luege, E. Oñate

  (2004). Research Report, Nº PI265

  
  

  Abstract

  This report present review of the state of the art of numerical modelling of polymers and polymer coated metal laminates and gives details of selected numerical models including those that will be used in the work in the project POLYCOAT. The first sections studied in the project. Basic mechanical and thermal properties of the polymers are reviewed. Then constitutive models developed for polymers are reviewed based on literature and own work. Details of selected models are given. Deformation behaviour of polymer coated metal laminates is considered with special attention to the phenomena observed at the polymer-metal interface. The numerical models for the interface are presented finally.

  Abstract
  This report present review of the state of the art of numerical modelling of polymers and polymer coated metal laminates and gives details of selected numerical models including [...]

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• El valor del cálculo en los sistemas de ayuda a la toma de decisiones en ingeniería

  E. Oñate

  Revista de Obras Públicas (2004). Vol. 151 (3449), pp. 41-48

  
  

  Abstract

  El artículo revindica el valor de los métodos de cálculo que se enseñan en las Escuelas de Ingeniería, como herramientas indispensables en los nuevos sistemas de ayuda a la toma de decisiones (SAD). Los SAD integran base de datos, métodos de cálculo y módulos de inteligencia artificial, y su utilización se extiende cada día más para ayuda al diseño y gestión de infraestructuras y servicios de ingeniería. En el texto se describen varios desarrollos y aplicaciones recientes de SAD en ingeniería civil. El artículo acaba con una reflexión sobre los límites de los SAD. The paper stresses the value of the computational methods taught in engineering faculties as indispensable tools within the new decision support systems (DSS). The DSS integrate data bases, computational methods and artificial intelligence modules. They are increasingly used for supporting the design and management of civil constructions and services in engineering. The paper describes recent developments and applications of DSS in civil engineering. The text ends up with a discussion on the limits of the DSS. 

  Abstract
  El artículo revindica el valor de los métodos de cálculo que se enseñan en las Escuelas de Ingeniería, como herramientas indispensables [...]

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