EECA - Escola de Engenharia Civil e Ambiental
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A Escola de Engenharia Civil e Ambiental (EECA), da Universidade Federal de Goiás, oferece os cursos de: Engenharia Civil e Engenharia Ambiental. Além de Especialização em: Gestão e Tecnologia de Produção de Edifícos; Especialização em Engenharia Civil; Planejamento e Gestão do Transporte e da Mobilidade Urbana; Planejamento e Gestão Ambiental; Tratamento e Disposição Final de Resíduos Sólidos e Líquidos; Engenharia de Segurança do Trabalho; e, Planejamento e Gerenciamento de Recursos Hídricos.
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Navegando EECA - Escola de Engenharia Civil e Ambiental por Autor "Araújo, Daniel de Lima"
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Item Análise da estabilidade lateral de uma viga pré-moldada de concreto para ponte em fases transitórias(Ricardo Prado Abreu Reis, 2019-06) Borghi, Graziela Borges; Lisboa, Guilherme de Paula; Araújo, Daniel de LimaConcrete structures, generally, do not present lateral instability problems. However, the transitory phases become a critical state for precast beams, since in these cases the temporary supports do not restrict the rotation and torsion in the elements, as in the definitive phases. As a result of this degree of liberty, the pieces may lose their equilibrium and shift laterally. Instability studies may be restricted to two main situations: the hanging element and the element over the elastic support. Given that normative recommendations, in general, have very simplistic safety parameters, in this paper, one design of a precast concrete beam is taken and its safety against lateral instability is evaluated according to two methods, one based on the equilibrium of forces in the rotated beam and the other on the determination of its critical load of lateral instability. These methods are compatibilized to the Brazilian standard indications and reevaluated. A sensitivity analysis is added to determine which variables have the greatest influence on the safety factors proposed by the methods. It is found that the safety indicators are reduced when compatibilization to national normatives is applied. Through the sensitivity analysis, it is noted that the use of overhangs during the transitory phases improves the safety levels.Item Avaliação da resistência de consolos de concreto moldados em duas etapas com a utilização de protensão não aderente(Ricardo Prado Abreu Reis, 2019-06) Chagas, Luiz Guilherme Mendonça; Nogueira, Izadora Ferreira; Oliveira Júnior, Luiz Álvaro de; Araújo, Daniel de LimaOne of the key advantages of precast concrete structures is the speed of construction. This advantage can be further evidenced if elements like columns with corbels could be produced in an even more agile way. This paper presents the results of an experimental research on short precast concrete corbels. Corbels are precast separately of the column and then joined to it by means of socked and unbonded post-tensioning. For this, three models composed by a column and two symmetric corbels, all of them precast, were produced, being their failure defined by splitting of concrete in corbels. Results also demonstrated that the proposed typology of corbel presented strength merely 5% lower than the reference monolithic corbel. In the other hand, the proposed typology of corbel provided strength significantly greater than that found for corbel cast in two steps without prestressing.Item Comparação entre a eficiência estrutural de perfis soldados de aço e perfis de aço formados a frio(Ricardo Prado Abreu Reis, 2016-12) Nogueira, Uiatan Aguiar; Melo, Matilde Batista Melo; Araújo, Daniel de LimaThe analysis of structural elements, in a structure’s design, is an essential step to ensure good performance and stability of the structural system. In any types of structures, such as roofing in buildings, it’s usual using cold-formed steel beams due to their small weight. This research seeks to evaluate the structural efficiency of cold-formed steel beams when compared, for example, to compact welded steel beams. Thus, bending tests were performed in four simply supported beams submitted to two concentrated loads, in order to obtain pure flexure at the mid-span of the beams. These beams were instrumented for the determination of their rigidity and bending strength. The results showed that the cold-formed steel beam, box-shaped, presented structural efficiency similar to the welded steel beam “H” shaped.Item Comparação entre modelos de cálculo de consolos para estruturas de concreto pré-moldado(2013) Silva Neto, Antonio Pereira da; Araújo, Daniel de Lima; Oliveira, Edilene Muniz de; Tenório, Helen OliveiraThe objective of this paper is to analyze different design models of corbels proposed by the main reinforced concrete structures codes. For this, two short corbels were tested and compared with the design models of the codes. Besides, an extensive database was made from the results of concrete corbels tests of the literature. Using statistical tools, the design models were applied to the corbels of this database. As a main result, there is a divergence between the results provided by the different design models and a good agreement between the experimental results and the Brazilian code.Item Computational modeling of steel fiber reinforced concrete beams subjected to shear(2010-03) Araújo, Daniel de Lima; Carmo, Luciano Caetano do; Nunes, Fernanda Gabrielle Tibúrcio; Toledo Filho, Romildo DiasComputational modeling has become a common activity to Civil Engineering researchers and professionals. Therefore, the knowledge about the mechanical behavior of materials is very important. To correctly model the mechanical behavior of concrete structures subjected to shear stress, it is necessary to determine the shear retention factor that accounts for the friction between the two surfaces of a crack. The objective of this study is to show how the shear retention factor of steel fiber reinforced concrete can be obtained from direct shear tests associated to computational modeling. A concrete matrix with compressive strength of 60 MPa, to which 1% and 2% content of steel fibers were added, was used for the shear tests. The stress-slip relationship was obtained from these tests, and the shear retention factor of the steel fiber reinforced concrete was determined from inverse analysis using the Finite Element Method software DIANA© 8.1.2. Finally, the shear retention factor and the influence of steel fibers on the cracks were validated from the computational modeling of steel fiber reinforced concrete beams subjected to shear available in the literature.Item Estabilidade global de estruturas reticuladas em concreto pré-moldado: influência da plastificação da ligação(2006-08) Araújo, Daniel de Lima; Ferreira, Marcelo Araujo; Debs, Mounir Khalil elItem Influence of steel fibers and mineral additions on cracking behavior of reinforced concrete tension members(2009-06) Oliveira Júnior, Luiz Álvaro de; Araújo, Daniel de Lima; Toledo Filho, Romildo Dias; Fairbairn, Eduardo de Moraes Rego; Andrade, M. A. S.In this work the influence of steel fibers and mineral additions (silica fume and fly-ash) on cracking behavior of reinforced concrete tension members was investigated. Hooked-end steel fibers with aspect ratio of 65 were used in volumes of 0.75%, 1.00% e 1.50%. Sixteen tension tests were performed in tension members 800 mm long with square cross section of 150 mm of side reinforced with single bar of CA-50 steel with diameter of 20 mm for determining crack widths. The results showed that steel fibers reduced the average crack width up to 75% and mineral additions improved cracking behavior of concrete. Crack widths were compared with suggested values by Brazilian, American and European recommendations, which were unsuitable for estimating crack width in steel fiber reinforced concrete.Item Influência da adição de fibras de aço na tensão de aderência de barras de aço retilíneas(2013-04) Araújo, Daniel de Lima; Danin, Alice Ribeiro; Melo, Matilde Batista; Rodrigues, P. F.Bonding between steel bars and concrete makes the two materials compatible, enabling the use of reinforced concrete as a construction material. If the bond is good, there will be less cracks, and the reinforcing bar will be better protected by the surrounded concrete. The aim of this research was to analyze the influence of steel fibers on concrete-steel bond strength. Therefore, pull-out tests were performed with thirty-three prismatic specimens measuring 200 mm x 300 mm x 150 mm. The variables analyzed were: bar diameter (10 mm, 12.5 mm, 16 mm and 20 mm); bond length (five and ten times the diameter); and the volume of steel fibers added to the concrete (1% and 2%). Short, steel, hooked fibers were used, 35 mm in length and with aspect ratio of 65. Based on the pull-out tests assays, the form and force of the rupture was determined in each specimen, Computational simulations of the specimens were also performed with bars of 100 mm in diameter. Both the results of the experimental tests and the modeling showed that the addition of fibers had little effect on the bond strength between the bar and the concrete. On the other hand, when the bond rupture occurred by splitting of the concrete cover, the influence of the steel fibers was significant.Item Influência de agregados reciclados de resíduos de construção nas propriedades mecânicas do concreto(Ricardo Prado Abreu Reis, 2016-02-08) Araújo, Daniel de Lima; Felix, Ludmylla Pires; Silva, Leonardo Costa e; Santos, Thiago Martins dosThe material loss in civil construction is large, which results in a great amount of construction waste. The latest environmental standards in Brazil do not allow that wastes are indiscriminately disposed of, and it is necessary to ensure their adequate final destination or, whenever possible, their reuse. The greater amount of construction waste is made up of concrete and mortar, called “grey waste”. The aim of this paper is analyze the replacement of natural aggregates with coarse recycled aggregates from grey construction waste. Several concrete mixes were produced with various substitution percentages (0%, 19%, 43%, 75%, 100%) of natural aggregates with coarse recycled aggregates to evaluate the influence of this substitution on the fresh and mechanical properties of the concrete. The most important mechanical properties analyzed are the compressive strength and modulus of elasticity. The results show that it is possible to replace up to 100% of the natural aggregate with recycled aggregates without reducing the compressive strength. In this case, the modulus of elasticity is reduced by only 12%. This suggests that recycled aggregates can be used in the production of structural concretes.Item Painel pré-moldado de argamassa armada com vermiculita expandida e reforçado com fibras de vidro(Ricardo Prado Abreu Reis, 2015-12) Araújo, Daniel de Lima; Cândido, Éricka da SilvaThe aim of this study is to determine the mechanical behavior of precast mortar panels containing expanded vermiculite. Three types of panels are analyzed, i.e., solid panels, hollow core panels and modified hollow core panels formed of a lightweight mortar pre-panel enveloped by a thin layer of grout. The panels are reinforced with a mesh steel or fiberglass fabric. The mechanical behavior of panels is determined from bending tests or compression tests under static loading. The use of mortars with expanded vermiculite as lightweight aggregate decreases the flexural strength of panels, but increases their thermal insulation by up to 10%. The use of fiberglass fabric prevents sudden failure of the modified hollow core panels. The main finding of this study is the technical feasibility of lightweight panels made of pre-cast panel mortar and expanded vermiculite reinforced with fiberglass fabric.Item Shear strength of steel fiber-reinforced concrete beams(2014-09) Araújo, Daniel de Lima; Nunes, Fernanda Gabrielle Tibúrcio; Toledo Filho, Romildo Dias; Andrade, Moacir Alexandre Souza deThis study analyzed the mechanical behavior of shear strength of steel fiber-reinforced concrete beams. Six beams subjected to shear loading were tested until failure. Additionally, prisms were tested to evaluate fiber contribution to the concrete shear strength. Steel fibers were straight, hook-ended, 35 mm long and aspect ratio equal to 65. Volumetric fractions used were 1.0 and 2.0%. The results demonstrated a great contribution from steel fibers to shear strength of reinforced concrete beams and to reduce crack width, which can reduce the amount of stirrups in reinforced concrete structures. Beam capacity was also evaluated by empirical equations, and it was found that these equations provided a high variability, while some of them have not properly predicted the ultimate shear strength of the steel fiber-reinforced concrete beams.Item Stress-strain curves for steel fiber-reinforced concrete in compression(2010) Oliveira Júnior, Luiz Álvaro de; Borges, Vanessa Elizabeth dos Santos; Danin, Alice Ribeiro; Machado, Daiane Vitória Ramos; Araújo, Daniel de Lima; Debs, Mounir Khalil el; Rodrigues, Paulo FernandoThis paper presents a study on the compressive behavior of steel fiber-reinforced concrete. In this study, an analytical model for stress-strain curve for steel fiber-reinforced concrete is derived for concretes with strengths of 40 MPa and 60 MPa at the age of 28 days. Those concretes were reinforced with steel fibers with hooked ends 35 mm long and with aspect ratio of 65. The analytical model was compared with some experimental stress-strain curves and with some models reported in technical literature. Also, the accuracy of the proposed stress-strain curve was evaluated by comparison of the area under stress-strain curve. The results showed good agreement between analytical and experimental data and the benefits of the using of fibers in the compressive behavior of concrete.