EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
Navegar
6 resultados
Resultados da Pesquisa
Item Optimization of partially connected composite beams using nonlinear programming.(2020) Silva, Amilton Rodrigues da; Neves, Francisco de Assis das; Sousa Junior, João Batista Marques deDue to concrete being consistently used in the filling of prefabricated linear steel structural floor slabs, the practice of constructing steel-concrete composite structures is becoming more and more popular. The joint action of the two materials is generally ensured by mechanical connectors that considerably increase the performance of the composite element structure. For a majority of practical cases, these elements are formed by a concrete slab connected to I-shaped steel beams. In this study, models of finite elements for the steel-concrete composite beams with partial interaction are optimized using the sequential linear programming algorithm. The design variables are considered with two approaches: in the first, only the parameters that define the cross section of the steel “I” profile vary, while in the second, besides the aforementioned parameters that define the cross section of the “I” profile, also considered are those that define the concrete section. In addition, the optimum distribution of the shear connectors along the composite beam are verified; in other words, the longitudinal rigidity of the deformable connection is considered to be a design variable. The design constraints are those defined in standard specifications referring to the dimensioning of concrete, steel and composite steel-concrete structures, as well as the side constraints with respect to the parameters defining the cross section and the step-size for the non-linear optimization algorithm. The results for the composite beam optimization problems are presented taking into consideration different boundary conditions. For a given optimized project, the analysis of the results is done regarding the influence of the constraints on the optimization process, the graph of the load-slip curve along the composite beam, and the values obtained for the design variables.Item Parametric modal dynamic analysis of steel-concrete composite beams with deformable shear connection.(2017) Lima, Wanderson Geraldo de; Neves, Francisco de Assis das; Sousa Junior, João Batista Marques deComposite structural elements of steel-concrete began to be used only in 1960 after the development of methods and constructive dispositions that ensured the functionality of these two materials together. In order to verify the importance of the participation of the axial mode in the frequency spectrum of the free vibration problem in composite beams with deformable shear connection, several analyses for 4 different boundary conditions and stiffness connection variation were performed. The analysis of the problem was carried out by development and computational implementation of a finite element for composite beams with partial interaction in the longitudinal direction applied to the problem of free vibrations. The solutions to this problem in the literature are scarce, and project recommendations are simplified. The results show that the finite element exhibits an excellent performance compared with the analytical results and as the axial mode has a high modal contribution, despite the boundary condition and stiffness connection.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 A numerical model for concrete slabs under fire conditions.(2013) Caldas, Rodrigo Barreto; Fakury, Ricardo Hallal; Sousa Junior, João Batista Marques de; Pitanqueira, Roque Luiz da SilvaA numerical model for the behavior of concrete slabs in a fire is described. This model consists of a shell finite element, a damage constitutive model for concrete with steel reinforcement and the consideration of heat transfer through the thickness of the slab. An improved damage constitutive model for concrete at elevated temperatures has been implemented considering compressive and tensile behavior through an orthotropic compliance theory. The damage in compression is based on the concrete stress–strain relationships presented by the European Committee for Standardization. Several calculations have been performed to validate the improved model. The comparison with experimental tests and numerical results confirm the validity of the approach for reinforced concrete slabs subjected to large transverse displacement.Item Membrane roof for an amphitheater in Brazil : searching for the optimal design.(2015) Nunes, Eliana Ferreira; Sousa Junior, João Batista Marques de; Baier, Bernd; Sarmanho, Arlene Maria CunhaThis paper addresses the investigation of the performance of a structural membrane roof project for an amphitheater in Ouro Preto, Brazil. It aims to improve the geometry of the roof structural system in order to withstand structural loads with minimal system mass. This investigation is based on nonlinear structural analysis. A set of design parameters was investigated leading to eight models with different geometry. The numerical analysis and comparison of the models showed that the optimal performance of these structures is a result of the refined adjustment of the spatial arrangement of the whole structure and the geometry of the membrane aiming for the form that reveals the best load path and improves the cooperative interaction among all components.Item Finite element implementation for the analysis of 3D steel and composite frames subjected to fire.(2014) Caldas, Rodrigo Barreto; Fakury, Ricardo Hallal; Sousa Junior, João Batista Marques deThis paper presents a finite element formulation for the numerical analysis of three-dimensional framed steel, reinforced concrete or composite steel and concrete structures subjected to fire. Several specialized and commercial programs may be used for the analysis of structures in fire condition. Within this context, the purpose of this work is to present the steps taken to extend a previously developed static analysis procedure with beam elements in order to cope with the thermal and structural analysis of structures under fire action. Physical nonlinearity and material propertydegradation considering the temperature distribution are taken into account at the cross section level, which is divided into quadrilateral or triangular finite elements. Thermal strains are considered through the effective strain concept, and the resulting nonlinear system of equations is solved by the Newton-Raphson scheme. The accuracy and capability of the formulation to simulate the behavior of framed structures under fire action are assessed through comparison with various numerical and experimental results.