Inácio Benvegnu Morsch

Geometrically nonlinear static and dynamic analysis of composite laminates shells with a triangular finite element

Geometrically nonlinear static and dynamic behaviour of laminate composite shells are analyzed in this work using the Finite Element Method (FEM). Triangular elements with three nodes and six degrees of freedom per node (three displacement and three rotation components) are used. For static analysis the nonlinear equilibrium equations are solved using the Generalized Displacement Control Method (GDCM) while the dynamic solution is performed using the classical Newmark Method with an Updated Lagrangean Formulation (ULF). The system of equations is solved using the Gradient Cojugate Method (GCM) and in nonlinear cases with finite rotations and displacements an iterative-incremental scheme is employed. Numerical examples are presented and compared with results obtained by other authors with different kind of elements and different schemes.

Numerical modeling of reinforced concrete structures: static and dynamic analysis

A numerical model using the Finite Element Method (FEM) for the nonlinear static and dynamic analysis of reinforced concrete (RC) beams, plates and shells is presented in this work. For this purpose, computer programs based on plasticity theory and with crack monitoring capabilities are developed. The static analysis of RC shells up to failure load is carried out using 9-node degenerated shell finite elements while 20-node brick finite elements are used for dynamic applications. The elasto-plastic constitutive law for concrete is coupled with a strain-rate sensitive model in order to take into account high loading rate effect when transient loading is intended. The implicit Newmark scheme with predictor and corrector phases is used for time integration of the nonlinear system of equations. In both cases, the steel reinforcement is considered to be smeared and represented by membrane finite elements. Various benchmark examples are solved with the present numerical model and comparisons with other published data are performed. For all examples, the path failure, collapse loads and failure mechanism is reproduced with great accuracy.

Proposta de elemento de integração para a interface entre alvenaria estrutural e esquadria

A utilizacao de sistemas modulares na industria da construcao tem crescido de forma acentuada nos ultimos anos no Brasil, sendo que, dentre estes, se destaca o sistema construtivo de alvenaria estrutural. Entretanto, diversos estudos apontam uma alta incidencia de manifestacoes patologicas relacionadas a este sistema. A interface entre alvenaria e esquadria e um dos locais de maior incidencia de problemas, alem de representar um gargalo construtivo, pela necessidade de realizacao de inumeras atividades que dependentes da mesma. O presente artigo apresenta o processo de desenvolvimento de uma nova solucao para este problema, denominada elemento de integracao, incluindo sua definicao geometrica, funcional e conceitual, bem como a producao de prototipos virtuais e fisicos (com diferentes materiais). Ao longo do desenvolvimento de diferentes modelos, foram realizadas avaliacoes pela equipe de projeto, a partir das quais foram introduzidas melhorias. Ao todo, foram produzidos 4 modelos virtuais, 3 modelos fisicos na escala 1:1, e uma parede experimental. Os principais resultados apontam para a viabilidade e adequacao da proposta ao sistema construtivo, bem como identificam o possivel aumento de construtibilidade do sistema como um todo a partir da aplicacao do elemento desenvolvido.

Customization of a software of finite elements to analysis of concrete structures: long-term effects

Resumo Concrete is a material that presents time-delayed effects associated with creep and shrinkage phenomena. The numerical modeling of the creep is not trivial because it depends on the age of the concrete at the time of loading, which makes necessary to store the history of loads to apply the principle of superposition. However, a problem formulated in finite elements has many points of integration, making this storage impossible. The Theory of Solidification, together with incremental algorithm developed by Bazant e Prasannan ([1], [2]), solves this problem. Therefore, this paper presents the adaptation of this algorithm to a finite element commercial software (ANSYS) considering the creep, according to the CEB-FIP Model Code 1990 [3]. The results demonstrate that the deformations provided by this adaptation are in accordance with the analytical solution given by the CEB-FIP MC90, including cases where the loads are applied at different ages of the concrete.

Finite element study of effective width in steel-concrete composite beams under long-term service loads

In this work, a finite element-based approach is presented to study the effective width variation in non-pre-stressed steel-concrete beams under the serviceability stage, including time dependent effects such as concrete creep, shrinkage and cracking. For this purpose, the viscoelasticity theory in conjunction with a nonlinear cracking monitoring algorithm is used to trace the nonlinear viscoelastic response of the structure along time. The present numerical model is fully three-dimensional and permits the inclusion of partial interaction at the slab-beam interface. A comprehensive study is carried out on the long-term response of a composite girder bridge previously studied by other researches. Then, previous results are revised and extended herein. Potential shortcomings of some standard codes related to the effective width evaluation are also investigated. It is demonstrated that the slab effective width varies sharply along the beam axis in the short-term, while it approaches to the actual slab width in the long-term. For the studied example, the common assumption of using only the middle layer of the reinforced concrete (RC) slab for the effective width calculation is revised with a through-thickness integration procedure. The influence of some creep and shrinkage models as well as the ultimate tensile concrete strain on the effective width response is also assessed. Finally, a simple formula is proposed to evaluate the short-term slab effective width for the studied example.