lucia karapitta - Academia.edu (original) (raw)
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Papers by lucia karapitta
Earthquake Engineering & Structural Dynamics, 2010
A simple constitutive model is proposed for an in-plane numerical analysis of unreinforced masonr... more A simple constitutive model is proposed for an in-plane numerical analysis of unreinforced masonry structures, which are subject to cyclic loading, by using explicit dynamic procedures. The proposed model is implemented by using two-dimensional plane-stress finite elements. Three different constitutive relations that are based on the total strain in the global material system are used. Cracking and crushing are controlled through normal strains, whereas shear is controlled through shear strain. Separate hysteretic rules are adopted for each mode of damage. A numerical analysis of masonry walls that are subject to cyclic loading has demonstrated that the use of explicit procedures in conjunction with the proposed model results in an acceptable accuracy when compared with the experimental results. Copyright © 2010 John Wiley & Sons, Ltd.
Computer Methods in Applied Mechanics and Engineering, 2002
TRIC is a simple but sophisticated 3-node shear-deformable isotropic and composite facet shell el... more TRIC is a simple but sophisticated 3-node shear-deformable isotropic and composite facet shell element suitable for large-scale linear and nonlinear engineering computations of thin and anisotropic plate and complex shell structures. In the present work an elasto-plastic constitutive model based on the von Mises yield criterion with isotropic hardening is incorporated into the element. The characteristic feature of this model is that the non-linear material behaviour is taken into account entirely in the natural system of the element. This is achieved by transforming quantities such as equivalent plastic strain, equivalent stress, the expression of the yield surface and the components of flow vector from the material coordinate system to the natural coordinate system. These transformations lead to simple and elegant expressions for the respective quantities in the natural system. This implementation leads to an efficient and cost effective treatment of the nonlinear analysis of arbitrary shells including material and geometrical nonlinearities.
The dynamic analysis of shells has attracted considerable interest in recent years. As analysts a... more The dynamic analysis of shells has attracted considerable interest in recent years. As analysts are increasingly performing more sophisticated simulations of complex structural models (some problems may comprise hundreds of thousands or even millions degrees of freedom) there is a great need for simple, and at the same time, accurate elements to conduct large-scale computational experiments. Furthermore, most available shell elements lack generality, that is, they are either isotropic or composite. In addition there is a trend in finite element analysis for numerical integration that calls for stiffness and mass matrices containing analytic algebraic expressions. To satisfy these requirements, a lot effort has been devoted to expand and further develop the natural mode finite element method for the analysis of isotropic and laminated composite shell structures. The product of this effort is the TRIC (TRIangular Composite) element, which has been presented in previous papers. The aim of this work is to present the behavior of the TRIC element in geometrical as well as nonlinear dynamic analysis of shells. γ σ J J J J σ J
Earthquake Engineering & Structural Dynamics, 2010
A simple constitutive model is proposed for an in-plane numerical analysis of unreinforced masonr... more A simple constitutive model is proposed for an in-plane numerical analysis of unreinforced masonry structures, which are subject to cyclic loading, by using explicit dynamic procedures. The proposed model is implemented by using two-dimensional plane-stress finite elements. Three different constitutive relations that are based on the total strain in the global material system are used. Cracking and crushing are controlled through normal strains, whereas shear is controlled through shear strain. Separate hysteretic rules are adopted for each mode of damage. A numerical analysis of masonry walls that are subject to cyclic loading has demonstrated that the use of explicit procedures in conjunction with the proposed model results in an acceptable accuracy when compared with the experimental results. Copyright © 2010 John Wiley & Sons, Ltd.
Computer Methods in Applied Mechanics and Engineering, 2002
TRIC is a simple but sophisticated 3-node shear-deformable isotropic and composite facet shell el... more TRIC is a simple but sophisticated 3-node shear-deformable isotropic and composite facet shell element suitable for large-scale linear and nonlinear engineering computations of thin and anisotropic plate and complex shell structures. In the present work an elasto-plastic constitutive model based on the von Mises yield criterion with isotropic hardening is incorporated into the element. The characteristic feature of this model is that the non-linear material behaviour is taken into account entirely in the natural system of the element. This is achieved by transforming quantities such as equivalent plastic strain, equivalent stress, the expression of the yield surface and the components of flow vector from the material coordinate system to the natural coordinate system. These transformations lead to simple and elegant expressions for the respective quantities in the natural system. This implementation leads to an efficient and cost effective treatment of the nonlinear analysis of arbitrary shells including material and geometrical nonlinearities.
The dynamic analysis of shells has attracted considerable interest in recent years. As analysts a... more The dynamic analysis of shells has attracted considerable interest in recent years. As analysts are increasingly performing more sophisticated simulations of complex structural models (some problems may comprise hundreds of thousands or even millions degrees of freedom) there is a great need for simple, and at the same time, accurate elements to conduct large-scale computational experiments. Furthermore, most available shell elements lack generality, that is, they are either isotropic or composite. In addition there is a trend in finite element analysis for numerical integration that calls for stiffness and mass matrices containing analytic algebraic expressions. To satisfy these requirements, a lot effort has been devoted to expand and further develop the natural mode finite element method for the analysis of isotropic and laminated composite shell structures. The product of this effort is the TRIC (TRIangular Composite) element, which has been presented in previous papers. The aim of this work is to present the behavior of the TRIC element in geometrical as well as nonlinear dynamic analysis of shells. γ σ J J J J σ J