Evandro Parente Junior

Geometrically nonlinear analysis of thin-walled laminated composite beams

The use of thin-walled composite beams in Engineering has attracted great interest in recent years. Composite beams and other structural elements tend to have thin walls due to the high strength of the material. Other important aspect is that, even without reaching large strains and without overcoming the elastic limit of the material, such as beams present geometric nonlinear behavior due to their high slenderness, leading to large displacements and rotations. In this paper, a three-dimensional frame finite element for geometric nonlinear analysis of thin-walled laminated composite beams is presented. The finite element uses the Total Lagrangian formulation in order to allow the treatment of large displacements, but with moderated rotations. The constitutive matrix of the laminated beams is evaluated through a suitable thin-walled beam theory. In this theory, the effects of the couplings for several layups are considered, but the effects of the warping and transverse shear are neglected. Comparisons with numerical experiments demonstrate the very good accuracy of the proposed finite element.

Local buckling and post-critical behavior of thin-walled composite channel section columns

This work presents a study of the behavior, performance and failure of thinwalled composite channel section columns. The study is carried-out using nonlinear finite element models of laminated columns, including geometric imperfections and material failure, as well as approximate analytical solutions based on the Classical Lamination Theory. The accuracy of the numerical model is assessed using experimental results available in the literature and very good results were obtained. The results show the influence of the column layup and wall thickness on the structural behavior of laminated columns, including the buckling mode and ultimate failure load. Finally, the numerical model is used to assess the accuracy of approximate closed-form expressions for evaluation of the local buckling loads of composite channel section columns.

AN OOP APPROACH FOR AN ISOGEOMETRIC COHESIVE INTERFACE ELEMENT

Edson Moreira Dantas Jr. Elias Saraiva Barroso edsonmdantas@yahoo.com.br Centro Universitário Unichristus Campus Dom Luis, 60160-230, Ceará, Fortaleza, Brazil elias.barroso@gmail.com Universidade Federal do Ceará Departamento de Engenharia Estrutura e Construção Civil, 60455-760, Fortaleza, Ceará, Brazil Evandro Parente Junior evandro@ufc.br Universidade Federal do Ceará Departamento de Engenharia Estrutura e Construção Civil, 60455-760, Fortaleza, Ceará, Brazil Abstract. Delamination is one of the biggest problems in fracture mechanics. One of the most used method to predict failure is the finite element method though cohesive elements. Since isogeometric methods are obtaining great visibility because of it geometric integration with CAD software (using it proper geometry), the present work discusses the computer simulation of fracture using isogeometric interface element. The discontinuity is inserted through knot insertion. An OOP discussion is raised since the IGA interface element is obtained simply and easily through a FEM /IGA framework. This approach allows the handling of 2D and 3D models with different element shapes and constitutive models in a simple and easily extensible way. The structures geometries are modeled using plane NURBS elements. The computational implementation developed in this work was verified and validated using using results available in the literature.

Nonlinear analysis of steel scaffolds for shoring of concrete structures

Shoring systems are temporary structures that should resist external loads during the construction of concrete structures. Therefore, the shoring system should have sufficient strength and stiffness to ensure the safety of the concrete structure until it becomes self-supporting. Unfortunately, a large number of accidents occur during the construction of concrete structures due to the failure of the shoring system, showing the importance of improving the knowledge about these structures. This work aims to study the behavior of steel scaffolds used in the construction of high-clearance concrete structures using three-dimensional finite element models considering both geometrical and material nonlinearities. The obtained results are in good agreement with experimental results available in literature. The results showed that the boundary conditions have a significant influence on the failure loads of steel scaffolds.