DECIV - Artigos publicados em periódicos
URI permanente para esta coleçãohttp://www.hml.repositorio.ufop.br/handle/123456789/497
Navegar
12 resultados
Filtros
Configurações
Resultados da Pesquisa
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 MotaPopulation 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.Item Análise estrutural de contêineres marítimos utilizados na construção civil.(2021) Souza, Flávio Teixeira de; França Junior, Adelmo Magalhães de; Sarmanho, Arlene Maria CunhaUma possibilidade para a redução do déficit habitacional ou para a construção de habitações provisórias pode ser a utilização de contêineres marítimos descartados ao fim de sua vida útil na cadeia logística. Pela sua finalidade, os contêineres são estruturas robustas. No entanto, a arquitetura geralmente requer a inclusão de aberturas, a modificação das condições de apoio e o empilhamento dos contêineres, levando a condições de serviço diferentes das originalmente previstas. Este trabalho visa avaliar a influência destas modificações no comportamento estrutural dos contêineres. Para isto foi feita uma análise numérica via Método dos Elementos Finitos no programa comercial SAP2000, considerando aberturas e variações nas condições de apoio sob carregamento oriundo do empilhamento. Os resultados numéricos foram comparados a prescrições de normas brasileiras, e indicaram a viabilidade da utilização dos contêineres na construção civil na maioria das situações. No entanto, a combinação de grandes aberturas e modificações de suas condições de apoio leva a grandes deslocamentos e a elevadas concentrações de tensões, indicando a necessidade da adoção de medidas complementares para assegurar seu bom funcionamento estrutural.Item Numerical implementation for conception of strut and tie models in reinforced concrete structures.(2020) Ladeira, Artur Hallack; Silva, Amilton Rodrigues da; Camargos, Bruno Henrique Lourenço; Mapa, Lidianne de Paula Pinto; Reis, Reinaldo Antonio dosO Modelo de Bielas e Tirantes pode ser uma excelente alternativa para o dimensionamento de elementos estruturais em concreto armado submetidos a estado plano de tensão e para regiões que apresentem descontinuidade de ordem geométrica ou estática, substituindo procedimentos empíricos por uma metodologia racional de projeto. Para tornar a concepção do modelo menos dependente da experiência do projetista, o presente artigo tem como objetivo aliar a técnica de otimização topológica ESO (Evolutionary Structural Optimization) ao Método dos Elementos Finitos para geração automática dos modelos de bielas e tirantes. O critério de evolução do método de otimização topológica adotado considera a eliminação de elementos menos solicitados em termos de tensão, a partir de uma análise elástico-linear. Nesse contexto, é possível obter soluções otimizadas de problemas complexos envolvendo o concreto estrutural. São apresentados três exemplos numéricos para comprovação e validação das formulações e técnicas implementadas, cujos modelos de bielas e tirantes obtidos apresentam boa concordância em relação às respostas encontradas em trabalhos científicos precursores sobre o tema.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 eThe 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.Item Numerical and experimental analysis of perforated rack members under compression.(2018) Neiva, Luiz Henrique de Almeida; Sarmanho, Arlene Maria Cunha; Faria, Vinícius de Oliveira; Souza, Flávio Teixeira de; Starlino, Juliane Aparecida BrazThis paper presents a numerical and experimental study of uprights with rack-type perforated section in coldformed profiles, subjected to axial compression. 18 tests were performed on uprights with fixed-ends under uniform compression load to obtain the ultimate load applied, along with the measurement of the displacements. A numerical model with material and geometric nonlinearities was calibrated with the experimental tests. Next, a parametric analysis with 64 different numerical models was performed, determining the ultimate loads of the models. These results, when compared to the DSM predictions, showed that the equations of DSM are unreliable to predict the strength of this type of perforated uprights. Therefore, based on the model results, modifications were proposed to the parameters of the DSM distortional mode curve, so that it can predict the strength of the models studied.Item Smoothing evolutionary structural optimization for structures with displacement or natural frequency constraints.(2018) Simonetti, Hélio Luiz; Almeida, Valério da Silva; Neves, Francisco de Assis dasThe Smoothing Evolutionary Structural Optimization (SESO) technique was extended to solve 2D elastic problems with constraint of displacements or natural frequencies. At the end of each finite element analysis, a scalar representing the sensitivity due to the removal of an element is calculated. Thus, the elements that have the lowest values are removed from the structure, while the displacements in prescribed locations are kept inside of limits stated or the first frequencies are maximized. The proposed technique proved to be adequate and efficient in the execution of shape and topological optimization.Item Optimal strut-and-tie models using smooth evolutionary structural optimization.(2016) Simonetti, Hélio Luiz; Almeida, Valério da Silva; Oliveira Neto, Luttgardes de; Neves, Francisco de Assis dasO presente artigo apresenta um procedimento numérico para a obtenção de algumas configurações dos modelos clássicos de bielas e tirantes para certas aplicações estruturais. Para isso, faz-se o uso do método dos elementos finitos com o uso de uma formulação em teoria elasto-linear plana para a geração do elemento finito. Esse procedimento de análise é acoplado com um processo de otimização topológica denominado de SESO - Smoothing Evolutionary Structural Optimization. Esse método SESO baseia-se no procedimento de diminuição progressiva da contribuição de rigidez de elementos ineficientes com menores tensões até que ele não tenha mais influência, como se este estivesse em processo de danificação. São avaliados e comparados alguns exemplos de estruturas onde já se conhece a configuração ótima obtida dos modelos clássicos de bielas e tirantes, onde se demonstra a potencialidade da presente formulação para aplicações em estruturas genéricas.Item Numerical analysis of composite steel-concrete columns of arbitrary cross section.(2005) Sousa Junior, João Batista Marques de; Caldas, Rodrigo BarretoThis paper presents a numerical formulation for the nonlinear analysis of slender steel-concrete composite columns of generic cross-sectional shape, subjected to axial force and biaxial bending. The cross section is defined in terms of a number of closed polygonal loops of a specific material, each one with its own stress-strain relation, with reinforcement bars embedded in the polygons. The material and geometrically nonlinear equlibrium problem is solved by the finite element method, with displacement-based stress resultant beamcolumn elements. The proposed scheme turns possible, with a unified treatment, to perform analyses of concrete-filled steel tubes, fully or partially encased steel profiles, or less usual cross sections present on composite construction. The robustness and accuracy of the formulation is verified against numerical and experimental results available in the literature.Item Topology optimization applied to 2D elasticity problems considering the geometrical nonlinearity.(2015) Fernandes, Walliston dos Santos; Almeida, Valério da Silva; Neves, Francisco de Assis das; Greco, MarceloTopological Optimization (TO) of structures in plane stress state with material elastic-linear behavior, buttaking into consideration the geometrical nonlinearities, was performed and the results are presented herein. For this process, an evolutionary heuristic formulation denominated SESO (Smoothing Evolutionary Structural Optimization) associated with a finite element method was applied. SESO is a variant of the classic evolutionary structural optimization (ESO) method, where a smoothing process is applied in the ‘‘hard-kill’’ process of element removal – that is, their removal is done smoothly, reducing the values of the constitutive matrix of the element as if it were in the process of damage. It has been demonstrated that this non-linear geometric phenomenon clearly influences the final optimized topology when compared to an optimum configuration obtained with the equilibrium equations written at an undeformed position. Some numerical examples from literature are presented in order to show the differences in the final optimal topology when linear and non-linear analyses are used, allowing the verification of the importance of correctly analyzing the final optimum topology and as such, demonstrate the advantages of SESO as a structural optimization method.Item Computational procedures for nonlinear analysis of frames with semi-rigid connections.(2005) Pinheiro, Leonardo; Silveira, Ricardo Azoubel da MotaThis 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.