DECIV - Artigos publicados em periódicos

URI permanente para esta coleçãohttp://www.hml.repositorio.ufop.br/handle/123456789/497

Navegar

Filtros

2005 - 200912010 - 201922020 - 20231

Configurações

Autor: search.filters.author.Silveira, Ricardo Azoubel da MotaAssunto: search.filters.subject.Finite element method

Resultados da Pesquisa

Agora exibindo 1 - 4 de 4
  • Nenhuma Miniatura Disponível
    Item
    Influence of inverted-v-braced system on the stability and strength of multi-story steel frames.
    (2023) Azevedo, Iara Santana de; Silva, Andréa Regina Dias da; Silveira, Ricardo Azoubel da Mota
    Population growth in urban centers, together with the lack of physical space, has led to the construction of increasingly tall and slender buildings. Multiple-story structures present substantial challenges to civil engineering because they have specific requirements for their design, construction, and use. The increased number of floors leads to more lateral displacements resulting from horizontal actions. Under these conditions, to ensure system stability, structural bracing components are commonly adopted. In addition, along with the use of more resistant materials and new construction techniques, it is necessary to improve the methodologies adopted in the structural analysis to offer professionals in the area the conditions to undertake safer and more economical projects with better speed and efficiency. Thus, in this study, numerical analyses were applied to steel planar reticulated structures to evaluate their stability and strength when inserting bracing systems. The study compared the arrangement of the bars and analyzed the influence of the parameters of the bracing systems, such as the properties of the cross-section and the position of the inverted-V-braced system. The MASTAN2 program was used to perform nonlinear static assessments using reticulated finite elements that considered both geometrical and physical nonlinearities. It was observed that the inverted-V-braced system had a substantial impact on all of the structures that were analyzed, providing increased stiffness and, as a result, significantly reducing the frame’s lateral displacement.
  • Nenhuma Miniatura Disponível
    Item
    Inelastic second-order analysis of steel columns under minor-axis bending.
    (2019) Gonçalves, Gilney Afonso; Silveira, Ricardo Azoubel da Mota; Silva, Andréa Regina Dias da; Silva, Jéssica Lorrany e
    The inelastic second-order behavior of steel structural columns under minor-axis bending is presented in this article. To study this behavior, a nonlinear frame element formulation is adopted in which the steel's plasticity process is accompanied at the nodal points of each finite element through the refined plastic-hinge method (RPHM). A tangent modulus approach is employed in order to consider the stiffness degradation in function of the internal forces' variation, and the second-order effects, residual stresses and geometric imperfections are considered in the modeling of column behavior. As a criterium for defining the ultimate limit state of the column cross-section, strength surfaces are adopted. These surfaces describe the interaction between the axial force and bending moment (N-M interaction diagrams). To solve the nonlinear equilibrium equation for the structural system, the Newton-Raphson method is used, coupled with continuation strategies. Columns with different slenderness, boundary and loading conditions are analyzed, and the results obtained are comparable to those found by other researchers. The results lead to the conclusion that the numerical approach adopted in this study can be used for a better behavioral understanding of the steel column under weak-axis bending.
  • Nenhuma Miniatura Disponível
    Item
    Computational procedures for nonlinear analysis of frames with semi-rigid connections.
    (2005) Pinheiro, Leonardo; Silveira, Ricardo Azoubel da Mota
    This work discusses numerical and computational strategies for nonlinear analysis of frames with semi-rigid connections. Initially, the formation of the nonlinear problem is analyzed, followed by the necessary computational approaching for its solution. After that, the matricial formulations and the mathematical modeling of flexible connections, as well as the insertion of the nonlinear process, are presented. Moreover, the necessary procedures for characterization of semi-rigid beam-column elements, the modified stiffness matrix, the internal forces vector and the updating of the connection stiffness along the incremental-iterative process are approached and illustrated through the text. In order to verify the success of the implementations and the considered algorithms, the results for some types of frames considering semi-rigid joints are compared with those supplied by literature. Some considerations and conclusions about the computational implementations and results obtained are presented at the end of this work.
  • Nenhuma Miniatura Disponível
    Item
    A numerical approach for equilibrium and stability analysis of slender arches and rings under contact constraints.
    (2013) Silveira, Ricardo Azoubel da Mota; Nogueira, Christianne de Lyra; Gonçalves, Paulo Batista
    Underground constructions, such as shafts, courtain walls, foundations, pipes and tunnels, use structural elements that are supported by a geological medium (soil or rock) or are used to support the geological medium loads. If the geological medium is unable to react under tension, the structural element is subjected to unilateral contact constraints and, during the deformation process, may loose contact with the surrounding medium at one or more regions. The present work proposes an alternative numerical methodology for the geometrically nonlinear analysis of structural systems under unilateral contact constraints. The nonlinear problem involves two different types of variables: the displacement field and the length and position of the contact regions. In order to solve the resulting algebraic nonlinear equations with contact constraints and obtain the structural equilibrium configuration, the present work proposes a two-level iteration solution strategy at each load step. The first solves the contact problem as a linear complementary problem using Lemke’s algorithm. The second updates the displacement field. A nonlinear beam-column element is used to model the structure, while a bed of springs is used to model the geological medium. The use of an updated Lagrangian formulation, together with continuation and optimization techniques minimize the errors along the equilibrium paths and enables one to trace convoluted non-linear equilibrium paths with a varying number of contact regions. Special attention is given to the behavior of curved unidimensional support systems such as arches and rings. The nonlinear behavior of four such support systems is studied. The results clarify the influence of the foundation position (above or below the structure) and its stiffness on the nonlinear behavior and stability of curved structures. Comparison of the present results with those found in literature demonstrates the accuracy and versatility of the proposed numerical strategy in the analysis of structural elements with unilateral contact constraints.