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.
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17 resultados
Resultados da Pesquisa
Item Influence of residual stress models prescribed in design codes for steel I-section behavior.(2022) Lemes, Igor José Mendes; Silva, Jéssica Lorrany e; Batelo, Everton André Pimentel; Silveira, Ricardo Azoubel da MotaNon-uniform cooling of steel cross-sections during the manufacturing process generates a state of residual stresses in the cross-section. Design codes describe the distribution of these stresses in different ways. This work aims to numerically investigate the influence of these models on the behavior of bare steel and steel-concrete composite sections by the curves: flexural stiffness-bending moment, moment-curvature and yield curves (initial and full yield). These procedures are important for the study of the simplified curves used in some methodologies of the refined plastic hinge method (RPHM) analysis. The study will use the strain compatibility method (SCM), where, if the axial strain of the cross-section point is known, the section stiffness is obtained using the tangential Young's modulus derived from the materials constitutive relationship. A fiber discretization algorithm is applied and the residual stresses are explicitly inserted into the fibers automatically. The methodology was calibrated using the moment-curvature relationship and the flexural stiffness-bending moment curve. These results were numerically stable and good convergence with literature data was obtained. In general, the residual stress model of the American standard (AISC, 2016) defines a larger elastic region within the interaction diagrams then European model (CEN, 2005). The results obtained showed that the initial yield curves for steel I-sections under minor axis bending require revision for application to RPHM, mainly due to the loss of symmetry in relation to the ''M'' axis in the normal force-bending moment (''NM'') interaction diagram.Item Advanced numerical study of composite steel-concrete structures at high temperature.(2021) Barros, Rafael Cesário; Silveira, Ricardo Azoubel da Mota; Maximiano, Dalilah Pires; Lemes, Igor José MendesThe composite steel-concrete structures use has several advantages, such as the reduction of cross-sectional dimensions and weight of the structure, which is one of the main reasons for it is use today. However, under fire situation, the material and mechanical properties changes, causing significant strength and stiffness loss as a result of temperature rise. In this work, the temperature influence on the behavior of composite steel-concrete structures is studied through an inelastic second order (ISO) numerical investigation. For this, two computational modules, CS-ASA/FA and CS-ASA/FSA are developed and adapted for the study of composite structures in fire. The first module calculates the temperature field in any cross-section. The second module performs the ISO analysis through the coupling between the Refined Plastic Hinge Method (RPHM) and the Strain Compatibility Method (MCD). In this way, the evolution of the temperature in cross-sec- tions, the interaction diagrams between axial force and bending moment and the structures equi- librium path as a function of the time in fire are presented for composite steel-concrete beams, columns and frames. The proposed numerical methodology success is proved by comparison with experimental and numerical responses available in the literature.Item Concentrated approaches for nonlinear analysis of composite beams with partial interaction.(2021) Carvalho, Tawany Aparecida de; Lemes, Igor José Mendes; Silveira, Ricardo Azoubel da Mota; Dias, Luís Eduardo Silveira; Barros, Rafael CesárioTwo plane displacement-based formulations with concentrated nonlinear effects for numerical analysis of composite beams are presented here. The effects of geometric nonlinearity, plasticity and partial shear connection are considered. In these two approaches, the co-rotational system is defined to allow large displacements and rotations in the numerical model. The first formulation is based to Strain Compatibility Method, where the sections strains are explicitly evaluated as well as the slipping at the steel-concrete interface. Thus, the axial and flexural stiffness of the cross section is determined in each step of the incremental-iterative process. The second methodology considers rotational pseudo-springs at the finite elements ends to simulate of plasticity. Further- more, the effects of partial interaction can not be simulated by the inherently rotational behavior of the pseudo-springs. Thus, the cracking and partial interaction effects are approached through effective moment of inertia defined by normative criteria. Four composite beams are simulated with these two formulations and compared by the load-displacements paths. In all numerical re- sult findings these formulations are closed and accurate to the experimental data presented in lit- erature.Item Numerical analysis of steel–concrete composite beams with partial interaction : a plastic-hinge approach.(2021) Lemes, Igor José Mendes; Dias, Luís Eduardo Silveira; Silveira, Ricardo Azoubel da Mota; Silva, Amilton Rodrigues da; Carvalho, Tawany Aparecida deA two-dimensional displacement-based formulation with a plastic-hinge approach for the numerical analysis of composite beams with partial shear connection is presented here. The co-rotational approach is applied in the numerical model to allow large displacements and rotations. The axial and transverse displacement functions are defined to avoid locking problems. The simulation of the materials and shear connection nonlinear behaviors are approached via the strain compatibility method (SCM), where the constitutive relations are explicitly used. The slip in the steel section–concrete slab interface is considered by the axial force decomposition in the cross-section level by the degree of composite action, without introducing degrees of freedom in the finite element. The numerical proposal of the present work is tested by simulating steel–concrete composite beams and comparing the obtained results with the experimental and numerical data already known. This formulation is verified as numerically stable and without locking phenomena, and good convergence with literature results was obtained. However, more refined finite element (FE) meshes are needed.Item Plastic analysis of steel arches and framed structures with various cross sections.(2021) Silva, Jéssica Lorrany e; Deus, Lidiane Rodrigues Reis Maia de; Lemes, Igor José Mendes; Silveira, Ricardo Azoubel da MotaThis paper presents a displacement-based numerical methodology following the Euler-Bernoulli theory to simulate the 2 nonlinear behavior of steel structures. It is worth emphasizing the adoption of co-rotational finite element formulations considering large displacements and rotations and an inelastic material behavior. The numerical procedures proposed considers plasticity concentrated at the finite elements nodes, and the simulation of the steel nonlinear behavior is approached via the Strain Compatibility Method (SCM), where the material constitutive relation is used explicitly. The SCM is also applied in determining the sections bearing capacity. Moreover, the present numerical approach is not limited to a specific structural member cross-sectional typology, with the residual stress models introduced explicitly in subareas of steel cross-sections generated by a 2D discretization. Finally, results consistent with the literature and with low processing time are presented.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 An efficient inelastic approach using SCM/RPHM coupling to study reinforced concrete beams, columns and frames under fire conditions.(2020) Pires, Dalilah; Barros, Rafael Cesário; Silveira, Ricardo Azoubel da Mota; Lemes, Igor José Mendes; Rocha, Paulo Anderson SantanaThis work has as its main objective the study of the behavior of reinforced concrete beams, columns and structural frames in a fire situation. To do so an efficient numerical formulation was developed, implemented and evaluated. When exposed to high temperatures, the characteristics of the materials deteriorate, resulting in a considerable loss of strength and stiffness of the structure. The CS-ASA (Computational System for Advanced Structural Analysis) was used to achieve the objective. This computer system was expanded for advanced analysis of structures in fire conditions, taking advantage of the existing features and adding new ones. Two new computational modules were created: CS-ASA/FA (Fire Analysis) and CS-ASA/FSA (Structural Fire Analysis). The first one was used to determine the temperature field in the structural elements’ cross-section through thermal analysis by the Finite Element Method (FEM) in permanent and transient regimes. The second was created to perform the second-order inelastic analysis of structures under fire using the FEM formulations based on the Refined Plastic Hinge Method (RPHM) and the Strain Compatibility Method (SCM) coupling, which can be considered a unique feature of the present study. The use of SCM allows for a more realistic analysis against the design codes prescriptions. Consequently, even under high temperatures, SCM is used for evaluation of both bearing capacity and stiffness parameters. The results of the nonlinear analysis in a fire situation for eight structural elements and systems with different geometries, boundary, heating and loading conditions are in good agreement with the numerical and experimental results found in the literature.Item Thermo-structural analysis of reinforced concrete beams.(2019) Maximiano, Dalilah Pires; Barros, Rafael Cesário; Silveira, Ricardo Azoubel da Mota; Lemes, Igor José Mendes; Rocha, Paulo Anderson SantanaThe objective of this study is to simulate the behavior of reinforced concrete beams in fire situation. In order to achieve this objective, advanced numerical formulations were developed, implemented and evaluated. When exposed to high temperatures, the properties of the material deteriorate, resulting in the loss of strength and stiffness. To achieve the goal, two new modules within the Computational System for Advanced Structural Analysis were created: Fire Analysis and Fire Structural Analysis. The first one aims to determine the temperature field in the cross section of structural elements through thermal analysis by using the Finite Element Method (FEM). The second was designed to perform the second-order inelastic analysis of structures under fire using FEM formulations based on the Refined Plastic Hinge Method coupled with the Strain Compatibility Method. The results obtained of the nonlinear analyses of two reinforced concrete beams under high temperature were compared with the numerical and experimental solutions available in literature and were highly satisfactory. These results also showed that the proposed numerical approach can be used to study the progressive collapse of other reinforced concrete structures in fire situation and extended to the numerical analysis of composite structures under fire condition.Item Advanced inelastic analysis of steel structures at elevated temperatures by SCM/RPHM coupling.(2018) Barros, Rafael Cesário; Maximiano, Dalilah Pires; Silveira, Ricardo Azoubel da Mota; Lemes, Igor José Mendes; Rocha, Paulo Anderson SantanaWhen exposed to high temperatures, the structural members and frames have their bearing capacity compromised because the physical characteristics and material resistance used in the structures deteriorate during exposure to fire, resulting in a considerable loss of strength and stiffness. In this context, the present work carries out a whole thermomechanical analysis of steel members and frames using the Finite Element Method (FEM) inelastic formulation based on the Refined Plastic Hinge Method (RPHM) coupled with the Strain Compatibility Method (SCM). The use of SCM allows for a more realistic analysis against the design codes prescriptions. So even under high temperatures, SCM is used for both evaluation of bearing capacity and stiffness parameters. To do this, the steel behavior used in the structure numerical modeling must be described in a consistent manner through its constitutive relationship. A comparison of the results obtained here with the numerical and experimental results available in the literature suggest the effectiveness of coupling SCM/RPHM and that such a methodology can provide reliable analyses of steel members and frames subjected to high temperatures.Item Numerical analysis of RC plane structures : a concentrated nonlinear effect approach.(2018) Lemes, Igor José Mendes; Barros, Rafael Cesário; Silveira, Ricardo Azoubel da Mota; Silva, Andréa Regina Dias da; Rocha, Paulo Anderson SantanaThe present work aims to study the nonlinear behavior of reinforced concrete structures via Refined Plastic Hinge Method (RPHM). Pseudo-springs are used at the finite element ends, where the gradual loss of stiffness is determined by the combination of the normal force and bending moment (NM) in the cross section. The limiting of the uncracked, elastic and plastic regimes is done in the NM diagram. The concrete cracking is explicitly simulated with two approaches to calculate the effective moment of inertia of the cross section. The displacement-based formulation is referenced to the co-rotational system and coupled with continuation strategies to allow to overcome the possible critical points in the equilibrium paths. For validation of the numerical simulations, the results found with the proposed formulation are confronted with experimental and numerical data present in literature.