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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5 resultados
Resultados da Pesquisa
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 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 Thermal analysis and vibrational spectroscopic characterization of the boro silicate mineral datolite - CaBSiO4(OH).(2013) Frost, Ray Leslie; Xi, Yunfei; Cipriano, Ricardo Augusto Scholz; Lima, Rosa Malena Fernandes; Horta, Laura Frota Campos; López, AndrésThe objective of this work is to determine the thermal stability and vibrational spectra of datolite CaBSiO4(OH) and relate these properties to the structure of the mineral. The thermal analysis of datolite shows a mass loss of 5.83% over a 700–775 °C temperature range. This mass loss corresponds to 1 water (H2O) molecules pfu. A quantitative chemical analysis using electron probe was undertaken. The Raman spectrum of datolite is characterized by bands at 917 and 1077 cm^-1 assigned to the symmetric stretching modes of BO and SiO tetrahedra. A very intense Raman band is observed at 3498 cm^-1 assigned to the stretching vibration of the OH units in the structure of datolite. BOH out-of-plane vibrations are characterized by the infrared band at 782 cm^-1. The vibrational spectra are based upon the structure of datolite based on sheets of four- and eight-membered rings of alternating SiO4 and BO3(OH) tetrahedra with the sheets bonded together by calcium atoms.Item The spectroscopic characterization of the sulphate mineral ettringite from Kuruman manganese deposits, South Africa.(2013) Frost, Ray Leslie; López, Andrés; Xi, Yunfei; Cipriano, Ricardo Augusto Scholz; Costa, Geraldo Magela da; Lima, Rosa Malena Fernandes; Granja, AmandaThe mineral ettringite has been studied using a number of techniques, including XRD, SEM with EDX, thermogravimetry and vibrational spectroscopy. The mineral proved to be composed of 53% of ettringite and 47% of thaumasite in a solid solution. Thermogravimetry shows a mass loss of 46.2% up to 1000 ◦C. Raman spectroscopy identifies multiple sulphate symmetric stretching modes in line with the three sulphate crystallographically different sites. Raman spectroscopy also identifies a band at 1072 cm−1 attributed to a carbonate symmetric stretching mode, confirming the presence of thaumasite. The observation of multiple bands in the _4 spectral region between 700 and 550 cm−1 offers evidence for the reduction in symmetry of the sulphate anion from Td to C2v or even lower symmetry. The Raman band at 3629 cm−1 is assigned to the OH unit stretching vibration and the broad feature at around 3487 cm−1 to water stretching bands. Vibrational spectroscopy enables an assessment of the molecular structure of natural ettringite to be made.