DECIV - Departamento de Engenharia Civil
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/496
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Item Optimized reinforcement distribution in reinforced concrete structures under plane stress state.(2022) Silva, Amilton Rodrigues da; Ladeira, Artur HallackThe strut-and-tie model is widely used for analysis and design of reinforced concrete structures. To apply this model, it is necessary to defne strut-and-tie systems that represent the fow of stresses generated in the analyzed structure. In many situations, this strut-and-tie model is defned through an evolutionary structural optimization (ESO) considering linear isotropic material. The results obtained from this model are not always satisfactory Query ID="Q1" Text="Please confrm the inserted city name and country name in afliations 1 and 2 are correct and amend if necessary." because of the nonlinear behavior of the concrete, mainly because of the great diference in the behavior under tension and compression. Because of this, an evolutionary algorithm is developed in this article to defne the optimized reinforcement distribution in reinforced concrete structures under plane stress state, considering the nonlinearity of the materials. This algorithm adopts the same principle as the ESO algorithm; however, it does not eliminate the mesh element that discretizes the analyzed domain, but it eliminates the reinforcement of the elements that do not meet an efciency criterion. A three-node triangular fnite element is used for nonlinear analysis of the reinforced concrete structure under plane stress state. The structure domain is discretized by this element, which can be of four types: with reinforcement in two fxed orthogonal directions, only in one direction, or without reinforcement. During the evolutionary process of the algorithm using a rejection criterion based on the level of reinforcement strain, the elements with reinforcement are changed to elements without reinforcement or with reinforcement in only one direction. Three practical applications were evaluated to verify the efciency of the algorithm proposed in this article. Two of them had their results compared with results provided in the literature, verifying the efciency of the proposed algorithm.Item Second-order inelastic analysis of shallow and non-shallow steel arches.(2020) Deus, Lidiane Rodrigues Reis Maia de; Silveira, Ricardo Azoubel da Mota; Lemes, Igor José Mendes; Silva, Jéssica Lorrany eThis work presents a second-order inelastic analysis of steel arches. The analysis of shallow and non-shallow arches with several cross sections and boundary and loads conditions are discussed. The computational platform used is the homemade CS-ASA, which performs advanced nonlinear static and dynamic analysis of structures. The nonlinear geometric effects are considered using a co-rotational finite element formulation; the material inelasticity is simulated by coupling the Refined Plastic Hinge Method (RPHM) with the Strain Compatibility Method (SCM), and the static nonlinear solution is based on an incremental-iterative strategy including continuation techniques. In the simulated nonlinear steel arch models, special attention is given to the equilibrium paths, the influence of rise-to-span ratio, support and loading conditions and full yield curves among other factors. The numerical results obtained show good agreement with those from literature and highlight that the arch rise-to-span ratio has great influence on the structure resistance and that the shallow arches can lose stability through the snap-through phenomenon.Item Nonlinear numerical analysis of prestressed concrete beams and slabs.(2020) Silva, Amilton Rodrigues da; Rosa, João Paulo de SouzaDue to the development of new constructive techniques, design of structures in prestressed concrete has been widely used in the practice. In this work the plate, bar and interface finite element formulations for numerical simulation of prestressed concrete beams and slabs is presented. Emphasis is given on the interface element that has the function of simulating a possible slip between the concrete and the prestress tendon as well as the stress and strain in that tendon. This interface element together with the proposed numerical model are the main contributions of this work. Some numerical and experimental examples obtained from the literature are used to validate the proposed model. In the numerical analysis presented in this article the concrete slabs are modeled with rectangular plate elements and the concrete beams modeled with bar elements. The active reinforcement and the contact between the active reinforcement and the concrete are modeled by interface elements. The geometric and material non-linearity are considered in the numerical analysis. The examples analyzed show the efficiency of the proposed model.Item Análise numérica do comportamento não linear de estruturas mistas de aço e concreto.(2017) Lemes, Igor José Mendes; Silva, Andréa Regina Dias da; Silveira, Ricardo Azoubel da Mota; Rocha, Paulo Anderson SantanaO presente trabalho apresenta o desenvolvimento de uma formulação numérica adequada para análise de estruturas mistas de aço e concreto considerando os efeitos da não linearidade geométrica e da inelasticidade dos materiais. Para tal, foi desenvolvida uma metodologia baseada no Método da Rótula Plástica Refinado (MRPR), sendo os coeficientes de rigidez obtidos por meio da homogeneização da seção transversal. A avaliação da capacidade resistente dos elementos estruturais é feita no contexto do Método da Compatibilidade de Deformações (MCD). Os problemas oriundos da consideração das fontes de não linearidade (global e local) são resolvidos por meio do método iterativo de Newton- -Raphson acoplado a estratégias de continuação. Os resultados obtidos são comparados com aqueles fornecidos em análises experimentais e/ ou numéricas presentes na literatura, sendo verificada boa precisão nas análises de seções transversais mistas, pilares isolados mistos e pórticos simples mistos.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.Item Avaliação numérica de ligações tubulares soldadas entre perfis circulares e vigas I considerando o efeito das cargas axiais.(2011) Reis, Sylvia Letizia Ferrarezi; Sarmanho, Arlene Maria Cunha; Araújo, Afonso Henrique Mascarenhas de; Lima, Luciano Rodrigues Ornelas deOs perfis tubulares sem costura são largamente utilizados em diversos países. No Brasil, o uso desses perfis na construção civil era bastante limitado, restringindo-se praticamente a coberturas espaciais. Considerando uma nova realidade com o incremento do uso de perfis tubulares, este trabalho apresenta uma análise de ligação tipo “X” uniplanar com perfis tubulares circulares para a coluna e perfis “I” para a viga. A rigidez da ligação foi avaliada através de um modelo em elementos finitos desenvolvido no programa Ansys. Foi feito um estudo considerando-se as relações entre diâmetro e espessura do tubo e o comprimento da mesa da viga de perfil “I” que influenciam na transmissão do momento, portanto na rigidez da ligação. Após a validação da metodologia empregada para modelagem das ligações, são apresentados os resultados obtidos numericamente e analiticamente. É analisado o comportamento momento versus rotação das ligações, portanto sua semi-rigidez. As não-linearidades físicas e geométricas foram incorporadas aos modelos, a fim de se mobilizar totalmente a capacidade resistente dessa ligação. Os resultados numéricos são comparados com resultados teóricos para a ligação em estudo e são avaliados os modos de falha e as cargas limites obtidas.