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  • 1
    Online Resource
    Online Resource
    Influence of the Harvesting Region on Batch Homogeneity of Ipe Wood (Tabebuia sp.) Based on Its Physical and Mechanical Properties
    MDPI AG ; 2022
    In:  Forests Vol. 13, No. 9 ( 2022-08-30), p. 1385-
    Details
    In: Forests, MDPI AG, Vol. 13, No. 9 ( 2022-08-30), p. 1385-
    Abstract: This paper aims to evaluate the hypothesis regarding the homogeneity of wood batches, as provided in the Brazilian standard for wooden structures ABNT NBR 7190 through an experimental study simulating the condition of a sawmill where the control of the harvest region, location of the sample in the trunk, edaphoclimatic condition, relief, and vegetation are variables that cannot be controlled. An experimental study was performed on 15 properties (3 physical and 12 mechanical) of Ipe (Tabebuia sp.) wood. Batches from three harvesting regions (Mucajaí [RR-A], Bonfim [RR-B] , and Cláudia [MT]) were used to verify the existence of significant differences between the properties of the three areas. The properties were obtained following the test methods established in ABNT NBR 7190-3, with 540 specimens being manufactured and characterized, prior to being submitted to a statistical analysis, where ANOVA was applied with the Anderson–Darling normality test, the homogeneity of variance of multiple comparisons, and the Tukey test. Statistical analysis indicated that the wood harvesting regions showed significant differences in six (40%) and non-significant differences in nine (60%) of the fifteen properties evaluated. Among the properties evaluated, the compressive strength parallel to the grain (fc0) showed significant differences. This property is used to classify the wood strength class according to the Brazilian standard ABNT NBR 7190-1. The batches from the harvesting regions RR-A, RR-B, and MT were classified using the strength classes D60, D50, and D50, respectively. These results directly impact the consideration of the homogeneity of the batches, considering that the sawmills receive samples from different regions. For future research, a num erical method can be applied to consider the influence of the wood harvesting area.
    Type of Medium: Online Resource
    ISSN: 1999-4907
    URL: Article
    DOI: 10.3390/f13091385
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2527081-3
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  • 2
    Online Resource
    Online Resource
    Numerical approach of the bond stress behavior of steel bars embedded in self-compacting concrete (SCC) and in ordinary concrete in pullout models
    EDUFU - Editora da Universidade Federal de Uberlandia ; 2014
    In:  Ciência & Engenharia Vol. 23, No. 2 ( 2014-03-11), p. 57-66
    Details
    In: Ciência & Engenharia, EDUFU - Editora da Universidade Federal de Uberlandia, Vol. 23, No. 2 ( 2014-03-11), p. 57-66
    Type of Medium: Online Resource
    ISSN: 0103-944X , 1983-4071
    Uniform Title: English
    URL: Issue
    URL: Journal
    URL: Article
    DOI: 10.14393/19834071.23.2.2014
    DOI: 10.14393/19834071
    DOI: 10.14393/19834071.2014.27784
    Language: Unknown
    Publisher: EDUFU - Editora da Universidade Federal de Uberlandia
    Publication Date: 2014
    detail.hit.zdb_id: 2623771-4
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Influence of mean value of the modulus of elasticity in compression parallel to the grain on the design of timber trusses
    Universidade Estadual de Maringa ; 2022
    In:  Acta Scientiarum. Technology Vol. 45 ( 2022-08-26), p. e58733-
    Details
    In: Acta Scientiarum. Technology, Universidade Estadual de Maringa, Vol. 45 ( 2022-08-26), p. e58733-
    Abstract: The Brazilian standard ABNT NBR 7190 (Associação Brasileira de Normas Técnicas [ABNT], 1997) recommends adopting the mean value of the modulus of elasticity to compression in the direction parallel to the grain (Ec0,m) in the calculation of displacements. The values of wood stiffness vary considerably, and they can generate displacements above the limit (L 200-1, where L is the span) established by the referred standard, which contributes to the appearance of pathologies in the structure. To evaluate the influence of the adoption of Ec0,m in the calculation of displacements, mechanical properties of wood species were obtained experimentally. With the aid of numerical models and experimental values, ten types of trusses were analyzed (Porch, Inclined Chord, Top Inclined Chord, Parallel Chord, Bowstring, Fink, Howe, K Truss, Pratt, Scissor), three spans (5, 10, and 20 m) and two species (Hymenolobium petraum Ducke e Hymenolobium sp). Initially, adopting Ec0,m for all members and performing a linear analysis, the maximum loads for the displacement L 200-1 were determined. Subsequently, experimental stiffness values were randomly assigned to each bar, and the maximum displacements were determined through nonlinear geometric analyses. Based on 1260 numerical simulations, deflections of approximately 17% (span of 5 m), 30% (span of 10 m), and 34% (span of 20 m) were observed to be higher than the result considering Ec0,m. This problem can be overcome by using non-destructive methods in the pre-classification of the structure bars, positioning the elements rationally in the regions of the highest demand.
    Type of Medium: Online Resource
    ISSN: 1806-2563 , 1807-8664
    URL: Article
    DOI: 10.4025/actascitechnol.v45i1.58733
    Language: Unknown
    Publisher: Universidade Estadual de Maringa
    Publication Date: 2022
    detail.hit.zdb_id: 2449424-0
    SSG: 7,36
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Fatigue design in reinforced concrete bridges according to Brazilian code
    International Journal for Innovation Education and Research ; 2021
    In:  International Journal for Innovation Education and Research Vol. 9, No. 3 ( 2021-03-01), p. 257-279
    Details
    In: International Journal for Innovation Education and Research, International Journal for Innovation Education and Research, Vol. 9, No. 3 ( 2021-03-01), p. 257-279
    Abstract: There has been an increase in the flow of freight vehicles commuting on Brazilian highways. Then, special attention to the structural performance of bridges regarding the fatigue in beams is needed. Brazil has neither normative metrology to study real data flow of vehicles, nor specific fatigue load train models and coefficients to the analysis and design of road bridges. The same load train that is used for general dimensioning, TB 450, is used for the fatigue verification. Hence, this work aims to verify if the current TB 450 is representative of the freight heavy vehicles with 2 to 9 axles concerning the effects of fatigue in the longitudinal reinforcement of beams of theoretical reinforced concrete bridges with two, three, and five beams. This verification is performed analyzing the stress variations found in the longitudinal reinforcement of vehicles with 2 to 9 axles and the TB 450. Based on the results, the longitudinal steel reinforcement was more susceptible to fatigue's effects. Freight vehicles with 5, 6, 8 and 9 axles presented the most significant stress, therefore, they tend to cause more deleterious effects. Hence, the adoption of a Brazilian normative fatigue specific load train and coefficients is necessary to analyze pre-existing road bridges and design new ones most accurately.
    Type of Medium: Online Resource
    ISSN: 2411-2933 , 2411-3123
    URL: Article
    DOI: 10.31686/ijier.vol9.iss3.2994
    Language: Unknown
    Publisher: International Journal for Innovation Education and Research
    Publication Date: 2021
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    Online Resource
  • 5
    Online Resource
    Online Resource
    Numerical approach of the steel-concrete bond behavior using pull-out models
    FapUNIFESP (SciELO) ; 2019
    In:  Matéria (Rio de Janeiro) Vol. 24, No. 2 ( 2019)
    Details
    In: Matéria (Rio de Janeiro), FapUNIFESP (SciELO), Vol. 24, No. 2 ( 2019)
    Type of Medium: Online Resource
    ISSN: 1517-7076
    URL: Article
    DOI: 10.1590/s1517-707620190002.0656
    Language: English
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2019
    detail.hit.zdb_id: 2715822-6
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  • 6
    Online Resource
    Online Resource
    Estudo comparativo sobre o projeto estrutural de lajes nervuradas e maciças em concreto armado na situação de incêndio
    Instituto Federal de Educacao, Ciencia e Tecnologia da Paraiba ; 2022
    In:  Revista Principia - Divulgação Científica e Tecnológica do IFPB Vol. 59, No. 2 ( 2022-06-30), p. 562-
    Details
    In: Revista Principia - Divulgação Científica e Tecnológica do IFPB, Instituto Federal de Educacao, Ciencia e Tecnologia da Paraiba, Vol. 59, No. 2 ( 2022-06-30), p. 562-
    Abstract: 〈 p class="Normal1" 〉 〈 span 〉 Quando comparadas às lajes maciças de concreto armado, as lajes nervuradas são projetadas de forma a aproveitar de maneira mais eficiente as qualidades existentes nos materiais que as constituem. Porém, a obrigatoriedade de verificação das estruturas em concreto armado para a situação de incêndio tende a diminuir essa vantagem econômica. Assim, este trabalho analisou o projeto de lajes maciças e nervuradas em concreto armado na situação de incêndio através das premissas das normas brasileiras. O dimensionamento das estruturas para diferentes imposições de projeto foi realizado com o auxílio do software CAD/TQS e, através de processo iterativo, foram obtidas as dimensões das lajes de forma que as flechas adquiridas ficassem o mais próximo possível das flechas máximas de cada vão. As imposições de projeto foram método construtivo, vãos, classe de agressividade ambiental, resistência do concreto e tempo requerido de resistência ao fogo, totalizando 256 lajes calculadas. Após o dimensionamento e através de tabelas e figuras gerados nos softwares Excel e Origin, realizou-se um estudo comparativo entre as lajes maciças e nervuradas, podendo-se concluir que as lajes nervuradas ainda são mais econômicas que as maciças, mesmo considerando a situação de incêndio. 〈 /span 〉 〈 /p 〉
    Type of Medium: Online Resource
    ISSN: 2447-9187 , 1517-0306
    URL: Article
    DOI: 10.18265/1517-0306a2021id5070
    Language: Unknown
    Publisher: Instituto Federal de Educacao, Ciencia e Tecnologia da Paraiba
    Publication Date: 2022
    detail.hit.zdb_id: 2908097-6
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  • 7
    Online Resource
    Online Resource
    M-N interaction curves for rectangular concrete-filled steel tube columns subjected to uniaxial bending moments
    FapUNIFESP (SciELO) ; 2022
    In:  Revista IBRACON de Estruturas e Materiais Vol. 15, No. 1 ( 2022)
    Details
    In: Revista IBRACON de Estruturas e Materiais, FapUNIFESP (SciELO), Vol. 15, No. 1 ( 2022)
    Abstract: resumo: Neste trabalho é proposto um processo computacional para obtenção de curvas de interação M-N para pilares mistos preenchidos de seção retangular, por meio da compatibilidade de deformações na seção transversal. Considerando flexão composta reta, foram desenvolvidas expressões que relacionam esforço normal, momento resistente, profundidade da linha neutra e resistência dos componentes da seção transversal. Tais expressões foram implementadas em uma ferramenta computacional que possibilita a definição dos pares resistentes M-N. As deformações específicas últimas de compressão do concreto e de tração no aço foram definidas com auxílio da norma brasileira para estruturas de concreto armado ABNT NBR 6118. Para verificação do processo elaborado, os resultados obtidos foram confrontados com curvas simplificadas traçadas de acordo com os modelos da ABNT NBR 8800, ABNT NBR 16239 e EN 1994-1-1 e com resultados da literatura. O modelo proposto apresentou boa concordância com resultados da literatura e estimou, com boa precisão, os momentos resistentes últimos. Por meio de um estudo paramétrico foi avaliada a influência da resistência à compressão do concreto, resistência ao escoamento do aço e taxa de aço nas curvas de interação M-N. Os resultados mostraram que a resistência ao escoamento do aço e a taxa de aço foram as variáveis que mais influenciaram nos valores resistentes (força normal e momento fletor).
    Type of Medium: Online Resource
    ISSN: 1983-4195
    URL: Article
    DOI: 10.1590/s1983-41952022000100008
    Language: English
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2022
    detail.hit.zdb_id: 2851703-9
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  • 8
    Online Resource
    Online Resource
    Dimensionamento de vigas protendidas contínuas pelo método das cargas equivalentes
    Instituto Federal de Educacao, Ciencia e Tecnologia da Paraiba ; 2023
    In:  Revista Principia - Divulgação Científica e Tecnológica do IFPB Vol. 60, No. 3 ( 2023-07-10), p. 713-
    Details
    In: Revista Principia - Divulgação Científica e Tecnológica do IFPB, Instituto Federal de Educacao, Ciencia e Tecnologia da Paraiba, Vol. 60, No. 3 ( 2023-07-10), p. 713-
    Abstract: 〈 p class="Normal1" 〉 O concreto protendido objetiva reduzir ou anular os efeitos de tração (fissuração) em um elemento de concreto. Considerando elementos isostáticos, o equacionamento e o cálculo consideram a adição de um momento fletor oriundo da aplicação do esforço de protensão a uma excentricidade do centro de gravidade da peça. Todavia, em estruturas hiperestáticas, o equacionamento e o cálculo são mais complexos, pois há consideração dos hiperestáticos de protensão oriundos da restrição do deslocamento no apoio. Portanto, é usual a representação pela superposição de efeitos de um sistema isostático protendido sob os efeitos dos esforços hiperestáticos oriundos da protensão. Entre as metodologias de cálculo existentes, tem-se o método da carga equivalente convencional proposto por Lin (1963). Nesse contexto, o presente estudo objetivou apresentar as considerações da literatura referentes ao momento hiperestático de protensão considerando esse método, em que foi calculada a armadura de protensão no estado limite último de uma viga protendida contínua, proposta por Kuchler (1993). Para tanto, apresenta-se também a determinação das perdas de protensão imediatas e ao longo da vida útil no cabo equivalente considerado. Ao final, a armadura de protensão obtida se assemelha ao exposto por Kuchler (1993), atestando a veracidade da metodologia empregada. 〈 /p 〉
    Type of Medium: Online Resource
    ISSN: 2447-9187 , 1517-0306
    URL: Article
    DOI: 10.18265/1517-0306a2021id6358
    Language: Unknown
    Publisher: Instituto Federal de Educacao, Ciencia e Tecnologia da Paraiba
    Publication Date: 2023
    detail.hit.zdb_id: 2908097-6
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  • 9
    Online Resource
    Online Resource
    Concreto autoadensável ecoeficiente com baixo consumo de cimento
    FapUNIFESP (SciELO) ; 2020
    In:  Ambiente Construído Vol. 20, No. 2 ( 2020-06), p. 59-71
    Details
    In: Ambiente Construído, FapUNIFESP (SciELO), Vol. 20, No. 2 ( 2020-06), p. 59-71
    Abstract: Abstract Self-compacting concretes must simultaneously present fluidity and cohesion without the presence of exudation and segregation. These necessary characteristics of concrete in the fresh state are usually possible only through high contents of fines and, consequently, higher consumption of cement for its production. The consolidation of this material has instigated the search for solutions to reduce cement consumption and CO2 emissions. Aiming to contribute to environmental sustainability and the cement industry, this research study investigated the technical and economic feasibility of self-compacting concrete with low cement consumption. The densities of the concretes were determined, as well as their resistance to compression and diametral compression traction. The study analysed three concretes with reduced cement consumption and one reference concrete. The water/cement, fibre limestone/cement and active silica/cement ratios were maintained constant, while cement consumption ranged from 434.00 kg/m3 to 325.50 kg/m3, thus achieving a reduction of up to 25% in cement consumption. The results showed that it is feasible to produce self-compacting concrete with low cement consumption, guaranteeing the quality of its mechanical properties, with approximately cost reductions and CO2 emission of 6% and 19% respectively in relation to the reference concrete.
    Type of Medium: Online Resource
    ISSN: 1678-8621 , 1415-8876
    URL: Article
    DOI: 10.1590/s1678-86212020000200387
    Language: Portuguese
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2020
    detail.hit.zdb_id: 2502088-2
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  • 10
    Online Resource
    Online Resource
    Lajes alveolares pré-fabricadas: estudo da influência do número e do instante de preenchimento de alvéolos no ganho de resistência à força cortante
    FapUNIFESP (SciELO) ; 2017
    In:  Matéria (Rio de Janeiro) Vol. 22, No. 4 ( 2017-10-02)
    Details
    In: Matéria (Rio de Janeiro), FapUNIFESP (SciELO), Vol. 22, No. 4 ( 2017-10-02)
    Abstract: ABSTRACT This paper discusses the influence of instances and quantity of filled cores on shear strength gain of pretensioned precast concrete hollow core slabs, by means of a theoretical study that uses the available equations given by ABNT NBR 14861 [3] for shear strength calculation, and an experimental study where slabs without core filing, with 02 or 04 cores filled before or after the release of the strands prestressing in the casting bed, were tested under shear strength. The theoretical study confirms the advantage of the core filling execution after the release of prestressing, converging from experimental study when 04 cores were filled and diverging from this when 04 cores were filled.
    Type of Medium: Online Resource
    ISSN: 1517-7076
    URL: Article
    DOI: 10.1590/s1517-707620170004.0235
    Language: Unknown
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2017
    detail.hit.zdb_id: 2715822-6
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