Estudo da influência do encruamento do aço e das tensões residuais no comportamento inelástico de pórticos planos via análise avançada

Abstract

In this work a geometrically exact formulation to consider material and geometric nonlinearities of steel plane frames, by Finite Element Method (FEM), using the concepts of distributed-plasticity is presented. An overview of the Advanced Analysis with the aim of characterizing the desirable attributes to develop a model for the Advanced Inelastic Analysis is outlined. A general theory based on a rigorous updated Lagrangian formulation is developed using the corotacional technique to obtain the tangent stiffness matrix of the element. The abilities for analyzing pin-ended joint members and, especially, to simulate different constitutive laws for the material, covering the process of loading and unloading, allowing a broader study of the effects of material properties on the behavior and structural resistance, were added to the original computational program version presented by LAVALL (1996) and later modified by ALMEIDA (2006). The layers model adopted to build the cross section of the members allows the identification of the plastified region through the cross section as well as facilitates the use of any kind of residual stresses distribution. Examples are presented that demonstrate the potentiality of the proposed formulation. Finally, the analyses of various structural models in order to study the influences of the strain-hardening and residual stresses in the inelastic behavior of plane frames are presented. The results showed a good correlation with those presented by various researchers, confirming the application of the formulation as a Method of Advanced Analysis.