Accurate estimation of average modulus of elasticity in compression parallel to the grain (Ec0) i... more Accurate estimation of average modulus of elasticity in compression parallel to the grain (Ec0) is of paramount importance for rational sizing of timber structures, given the use of this property in the estimation of stability of compressed parts (ultimate limit state, ULS) and in calculation of excessive strains (serviceability limit state, SLS). In Brazil, if values cannot be experimentally determined, ABNT NBR 7190 (1997) allows for estimation of Ec0 through relations to average modulus of elasticity both in tension parallel to the grain (Et0) (Ec0 = Et0) and in bending (EM) (Ec0 = EM/0.90). This research aimed to access the efficiency of these relations by testing 30 tropical wood species. The analysis of variance results showed that Ec0 and Et0 were statistically equal. However, Ec0 and EM/0.90 were not statistically equal, and the method of least squares resulted in a coefficient of 0.98, which was 8.89% higher than the one suggested by ABNT NBR 7190 (1997) and close to 1, thu...
A lama abrasiva ou lama de marmoraria refere ao residuo gerado no beneficiamento de rochas orname... more A lama abrasiva ou lama de marmoraria refere ao residuo gerado no beneficiamento de rochas ornamentais nos processos do corte e polimento. Esse residuo depositado no meio ambiente, pode trazer consequencias prejudiciais aos recursos hidricos, contaminando o lencol freatico e solo, e acarretando na descaracterizacao da paisagem natural. Devido ao numero crescente de exportacao de rochas processadas no decorrer dos anos e a grande expansao do uso dessas rochas no mercado brasileiro da construcao civil, o volume do residuo e sua disposicao tem sido considerado preocupante. Dessa forma, o estudo do reaproveitamento dessa lama demonstra ser importante para a contribuicao da reducao do volume nos aterros e/ou descartes irregulares provocando danos ao meio ambiente. O presente artigo tem como objetivo avaliar o comportamento do uso do residuo de po da lama de marmoraria no concreto e verificar a durabilidade atraves dos ensaios de resistividade eletrica superficial e resistividade eletrica...
Este trabalho apresenta a proposta de geometria de corpo de prova para ensaio de tracao paralela ... more Este trabalho apresenta a proposta de geometria de corpo de prova para ensaio de tracao paralela as fibras da madeira e adotado na NBR-7190 e a proposta de dimensionamento, pelo Metodo Semi-Probabilistico, de uma peca de madeira submetida a tracao paralela as fibras. Exemplo de dimensionamento com dados de resistencia oriundos de pesquisa experimental, nacional e internacional e apresentado.
A good part of the Estrada Real´s bridges, road that goes through Minas Gerais historical region,... more A good part of the Estrada Real´s bridges, road that goes through Minas Gerais historical region, are made by woodand a few of them are found in precarious preservation condition , these bridges need a recorvering that won’talterate their functions and also the historical time they were built up.The research’s main goal is to determine the best solution of the recovery of pathologies found in the constructorsystem used for the most wood bridges from Estrada Real. After analyzing some of the bridges found in Ouro Pretoarea, it was discovered that bridges were executed over circular beams, with 32 cm of average diameter, doublerested,with 11 meters of average gaps and 3 meters of average width. The bridges trays are found in reasonablestate of conservation. The main beams have two pathology types: some were deteriorated by fungus attacks and theothers exhibit excessive deformation of flexure.
Buscou-se, através deste trabalho, fornecer parâmetros comparativos sobre o comportamento mecânic... more Buscou-se, através deste trabalho, fornecer parâmetros comparativos sobre o comportamento mecânico e físico das alvenarias de vedação construídas em blocos cerâmicos vazados e em painéis de concreto celular autoclavado (CCA). Avaliou-se, através de ensaios laboratoriais a resistência à compressão simples e o deslocamento horizontal, a resistência à flexão e o deslocamento vertical ocasionado por esta flexão, a permeabilidade à água e impacto de corpo mole. Investigouse também o comportamento isolado dos dois tipos de argamassa industrializadas usadas nos ensaios-argamassa de assentamento e argamassa colante-de forma a verificarse diferenças significativas que pudessem comprometer os resultados do conjunto. Os resultados do trabalho foram consistentes, apontando para diferenças significativas entre o comportamento dos componentes e os sistemas analisados, tanto nos ensaios individuais, como nos ensaios de paredinhas ou de paredes.
Tropical species are widely used in construction, and their physical and mechanical properties ha... more Tropical species are widely used in construction, and their physical and mechanical properties have been important characteristics with direct impact on the design of structures, especially the strength and stiffness of wood applied in them. Tests to obtain both parameters are conducted under ABNT NBR 7190 (1997) guidelines in Brazil, being rarely found in some research centers because of the higher costs of testing equipment. For instance, the toughness test depends on equipment with a pendulum, whose device requires accuracy and maintenance for reliable analyses. This paper aims to estimate toughness through another property more easily found, given by the compression strength parallel to the grain. For this, 20 tropical wood species of the South American region were used to obtain initial values of these properties. The characteristic values of the compression strength parallel to the grain as well as linear and quadratic regression models were obtained. Statistical analysis was ...
Investigations into the fire resistance of high-strength concrete (HSC) is extremely important to... more Investigations into the fire resistance of high-strength concrete (HSC) is extremely important to optimize structural design in construction engineering. This work describes the influence of polypropylene fibers on the mechanical properties and durability of HSC at high temperatures (25, 100, 200, 400, 600 and 800 °C). HSC specimens with 2 kg/m3 composed of polypropylene fibers are tested in a temperature range of 25 to 800 °C, followed by microstructural analysis. In addition, a statistical analysis is designed to identify the effect of factors, namely temperature and polypropylene fibers, and their interactions on mechanical properties and water absorption, electrical resistivity, mass loss and ultrasonic velocity. Most of the properties are improved by the incorporation of fibers, obtaining highly predictable regression models. However, the polypropylene fibers reduce compressive strength but improve the residual mechanical properties up to 400 °C.
RESUMO A madeira é um excelente material estrutural, além de possuir excelente resistência tanto ... more RESUMO A madeira é um excelente material estrutural, além de possuir excelente resistência tanto à tração como compressão. Para o dimensionamento correto, as premissas da norma brasileira são de estrema valia como norte para os engenheiros estruturais, pois exibe valores padrão de resistência. Dessa forma, esse estudo tem como objetivo analisar se o valor de resistência ao cisalhamento característico paralelo às fibras da classe C60 exibido na norma brasileira confere com os valores obtidos em ensaio de 23 espécies brasileiras, utilizando a metodologia Bootstrap com 1 milhão de simulações. Além disso, buscou analisar, com modelos de regressão, se é possível estimar a propriedade de resistência (fν0) dessas 23 espécies em função da densidade aparente, buscando assim uma obtenção rápida das propriedades dessas espécies com apenas a densidade aparente. Por final, foi possível concluir que a norma brasileira subestima a resistência ao cisalhamento das madeiras brasileiras, apresentado u...
O presente estudo tem por objetivo a análise técnico-econômica de edifícios de 3 a 21 pavimentos,... more O presente estudo tem por objetivo a análise técnico-econômica de edifícios de 3 a 21 pavimentos, com aplicação de distintos valores de resistência característica à compressão aos 28 dias (fck), variando entre 25 e 40 MPa, com relação geométrica, em planta, de 1:4. Estimase que, por meio dos resultados obtidos, seja possível auxiliar a concepção, o dimensionamento e, principalmente, subsidiar a orçamentação da superestrutura de edifícios em concreto armado que contemplem tal relação geométrica. De posse dos resultados, conclui-se que: (I) o aumento do valor do "fck" implica na redução significativa das dimensões dos elementos dos subsistemas verticais e no consumo de aço; (II) para cada caso analisado ("A" até "F"), as espessuras médias dos pavimentos tipo e o consumo de fôrmas se mantiveram praticamente constantes independentes do aumento do valor de "fck"; (III) a composição de custos mostrou que os sistemas dimensionados com concretos de resistência (C-35) geram menores custos globais. Palavras-chave: Concepção estrutural, Consumo de materiais e insumos, estruturas de concreto armado ABSTRACT This study aimed to technical and economic analysis of buildings 3-21 floors, with application of different characteristic values compressive strength at 28 days (fck), ranging between 25
International Journal of Materials Engineering, 2018
Wood has long been used by man for a wide range of purposes, including the production of furnitur... more Wood has long been used by man for a wide range of purposes, including the production of furniture, civil construction and structural elements. Aiming the construction industry, the use of glued laminated timber proves to be an excellent alternative to constructive technology, allowing the production of elements with different shapes and sizes. It is important that the bonded wood presents resistance to the stresses imposed on its use. This way, the present study aims to make a comparative analysis of shear strength values of Glued Laminated Timber (also called glulam) through the analysis of studies done by several authors that used different types of wood and adhesives. The results found by these authors were verified based on the ASTM-D-5751 and the Brazilian standard ABNT NBR 7190. It was concluded that the glued joints analyzed obtained satisfactory resistance according to the American standard. However, the majority did not comply with the parameters required by the Brazilian standard.
International Journal of Materials Engineering, 2018
The three point bending test, according the Brazilian Standard ABNT NBR 7190, enables to identify... more The three point bending test, according the Brazilian Standard ABNT NBR 7190, enables to identify the values of two wood properties: conventional modulus of elasticity and conventional strength on static bending test. With the results, this study aimed to perform a numerical simulation using the finite element software ABAQUS and the experimental results of three point bending test using Simarouba amara Aubl wood specie test proofs. Two analysis were performed, considering wood as elastoplastic material in the first and the second, considering only elastic material. From stress-strain diagrams results, it was observed the evaluation of modulus of elasticity on static bending test is not valid due to material non-linearity. A constitutive model was proposed for Simarouba amara Aubl. wood specie and for evaluation of modulus of elasticity on static bending. It was performed a comparative analysis between experimental results and the proposed constitutive model. These models showed their efficiency when evaluated the normal stress on proof test with demonstrated accuracy, allowing its use by wood structures designers.
International Journal of Materials Engineering, 2017
The purpose of this research is to demonstrate, in an original study, the potentiality of the use... more The purpose of this research is to demonstrate, in an original study, the potentiality of the use of Cajueiro (Anacardium sp.) and Amescla (Trattinikia sp.), two low density tropical wood species, for producing OSB (Oriented strand boards), structural panels that replace plywood for several building purposes. In those panels, wood strands can be disposed in a specific direction or in random distribution, in order to reach the desirable mechanical properties. In this case, the strands were oriented by a separator to generate layers in mass proportion 20:60:20 (outer, inner and outer layers). Then these pre-panels went to a pre-pressing to form the mattress. Finally, they were pressed at 100°C, by 10 minutes, under 4.5MPa pressure, using castor oil based bicomponent polyurethane resin as adhesive. They were produced eight panels (four with Cajueiro e four with Amescla), with nominal dimensions 350mm length, 350mm width and 10mm thickness. Results showed that these wood species can be used to produce OSB, mainly considering values obtained in mechanical tests, that are superior to OSB produced in Brazilian enterprises and can be classified as OSB/4, as recommended by European standard EN 300. Research should continue to be developed in order to reach more adequate performance in swelling and water absorption.
The fiber saturation point (FSP) is an important parameter of wood material, related to dimension... more The fiber saturation point (FSP) is an important parameter of wood material, related to dimensional stability and variations of mechanical performance. This paper investigated the FSP values of 15 tropical Brazilian wood species covering all strength classes of the Brazilian standard code. An additional goal was to estimate FSP value based on the wood’s apparent density. The FSP values were determined by measuring the wood specimen dimensions during moisture content reduction from the saturated state. Wood densities at 0% and 12% moisture contents and basic density were determined according to the Brazilian standard code. The average FSP for all wood species was 21.6% moisture content. Among density values, good correlations were observed, and a multivariate regression model for FSP estimation based on wood densities presented a coefficient of determination equal to 13.07%. There was no correlation between FSP and wood densities, suggesting that this parameter is almost constant reg...
Wood engineered products are alternatives to the use of timber for civil construction, manufactur... more Wood engineered products are alternatives to the use of timber for civil construction, manufacturing, and the furniture industry. One of these products is the medium density particleboard (MDP) panel, which is made of wood particles and resin under high temperature and pressure. This research produced a prototype to evaluate the use of MDP panels waterproofed by castor oil-based polyurethane resin and Pinus sp. residues treated with CCB preservative for use as a wall coating. The influence of weathering, position of wood panel, and waterproof treatment were evaluated. Panels were made under the requisites of Brazilian Standard ABNT NBR 14810 (2013) and evaluated with international standards. MDP panels met standard requisites, with properties similar to that reported in the literature, indicating the possibility of use as wall coating. Statistical analysis indicated the only significant factor was weathering, which influenced physical and mechanical properties.
International Journal of Materials Engineering, 2018
Wood is widely used in many sectors of civil construction as a structural material. Brazilian cod... more Wood is widely used in many sectors of civil construction as a structural material. Brazilian code ABNT NBR 7190:1997 "Design of Timber Structures" governs the method of project design as well as the characterization of wood for structural design. In this aspect the code considers wood as an orthoptic material, however is well known that the organic origin provides great anatomical complexity to its. This work aims to study the distribution of normal stresses in a Tauari wood beam subjected to the elastic regime, and to ascertain the current position of the Neutral Line during test. For this purpose, a four-point static bending test and subsequent compression and tension to the grain tests were performed to determine the modulus of elasticity and calculate the normal stresses by recording deformations and applying Hooke's Law. The data were statistically analyzed to define bests adjusts to Stress vs. Strain diagrams, and thus determine the location of the Neutral Line. It was verified that the position of the Neutral Line was a normal distribution variable, being located at 1,07cm above the geometric center of the board. Finally, the comparison between values of normal tension obtained experimentally and through the theoretical method was determined and similarities were verified in these data, being also plausible the theory for the calculation of the normal tensions of the wood beams, when it is in the elastic regime.
International Journal of Materials Engineering, 2017
The most commons woods used for production of medium density particleboard (MDP) are Eucalyptus a... more The most commons woods used for production of medium density particleboard (MDP) are Eucalyptus and Pinus. The Cajueiro and Amescla wood are typical trees coming from the center-west of Brazil, from the States of Mato Grosso and Tocatins. These are medium density woods similar to Pinus sp, the Brazilian's wood's industries usually used these woods only as piece of wood for structures or furniture. The purpose of this research is to investigate, in a preliminary study, the possibility of MDP panel's production using Cajueiro and Amescla wood species. The panels were produced under a pressure of 4 MPa for 10 minutes at 100°C, and it was produced a total of 12 MDP panels, 6 of Cajueiro and 6 of Amescla, with a thickness of 10mm, dimensions 250mm×250mm and 0.5 kg mass. For the bending modulus of elasticity, 2200 MPa were obtained for Cajueiro and 2700 MPa for Amescla, which are considered good values. The results can be considered satisfactory because it is a preliminary and unpublished study in the case of MDP panels manufactured with Cajueiro and Amescla wood species.
In wood structures, the elements subjected to bending stresses, such as the beams, present a frac... more In wood structures, the elements subjected to bending stresses, such as the beams, present a fracture initiated in the tensile region, and under these conditions, the use of laminated composite materials is presented as an alternative solution in the form of repair or reinforcement. This research aimed to evaluate the influence of the use of carbon fibers laminated composites in tensile reinforcement in the direction parallel to grain of Pinus elliotti and Manilkara huberi wood species. The Viapol two-component epoxy adhesive was used in the lamination and fixation of the unidirectional carbon fiber in the wood species. Ten specimens with no defects (reference) and 10 specimens were prepared for each crack length (25 and 50mm) with and without the reinforcement (60mm × 50mm) by the laminated composite. The tensile tests were performed in accordance with the requirements of the Brazilian standard ABNT NBR 7190 (1997). From the results of the statistical analysis, the use of the carbon fiber composite was able to restore the tensile strength of the cracked samples (partial or total) in relation to samples without defects, demonstrating the potential of the laminates in carbon fibers as an alternative solution in repair for both wood species.
International Journal of Materials Engineering, 2018
The study of pull out strength of glued in rods perpendicularly to the grain is presented. Three ... more The study of pull out strength of glued in rods perpendicularly to the grain is presented. Three types of resin were used in order to evaluate their efficiency. Additionally, the effects of the variation of the moisture content and of the glue line thickness were considered. The beams were made of wood from Corymbia citriodora, (ρ 12% = 1000 kg/m 3) and Pinus oocarpa Shiede (ρ 12% = 550 kg/m 3). The wood specimens (four samples for each type of test) were seasoned to the expected moisture contents of 12, 15, 18 and 22%. The anchorage length of the glued in rods was 80 mm, the hole diameters were 7.5, 8.5, 9.5 and 10.5 mm and their respective glue line thickness, 0.6, 1.1, 1.6 and 2.1 mm. The deformed reinforcing bars used as rods, with the minimum yield strength of 500 MPa, had nominal diameter of 6.3 mm. The obtained results confirmed the assumption that type of resin, moisture content, glue line thickness are strength determining factors, while density is less than others. The results are presented in a comparative form. The failure modes are discussed and the need of a broad understanding of resin behavior on wood was emphasized.
Accurate estimation of average modulus of elasticity in compression parallel to the grain (Ec0) i... more Accurate estimation of average modulus of elasticity in compression parallel to the grain (Ec0) is of paramount importance for rational sizing of timber structures, given the use of this property in the estimation of stability of compressed parts (ultimate limit state, ULS) and in calculation of excessive strains (serviceability limit state, SLS). In Brazil, if values cannot be experimentally determined, ABNT NBR 7190 (1997) allows for estimation of Ec0 through relations to average modulus of elasticity both in tension parallel to the grain (Et0) (Ec0 = Et0) and in bending (EM) (Ec0 = EM/0.90). This research aimed to access the efficiency of these relations by testing 30 tropical wood species. The analysis of variance results showed that Ec0 and Et0 were statistically equal. However, Ec0 and EM/0.90 were not statistically equal, and the method of least squares resulted in a coefficient of 0.98, which was 8.89% higher than the one suggested by ABNT NBR 7190 (1997) and close to 1, thu...
A lama abrasiva ou lama de marmoraria refere ao residuo gerado no beneficiamento de rochas orname... more A lama abrasiva ou lama de marmoraria refere ao residuo gerado no beneficiamento de rochas ornamentais nos processos do corte e polimento. Esse residuo depositado no meio ambiente, pode trazer consequencias prejudiciais aos recursos hidricos, contaminando o lencol freatico e solo, e acarretando na descaracterizacao da paisagem natural. Devido ao numero crescente de exportacao de rochas processadas no decorrer dos anos e a grande expansao do uso dessas rochas no mercado brasileiro da construcao civil, o volume do residuo e sua disposicao tem sido considerado preocupante. Dessa forma, o estudo do reaproveitamento dessa lama demonstra ser importante para a contribuicao da reducao do volume nos aterros e/ou descartes irregulares provocando danos ao meio ambiente. O presente artigo tem como objetivo avaliar o comportamento do uso do residuo de po da lama de marmoraria no concreto e verificar a durabilidade atraves dos ensaios de resistividade eletrica superficial e resistividade eletrica...
Este trabalho apresenta a proposta de geometria de corpo de prova para ensaio de tracao paralela ... more Este trabalho apresenta a proposta de geometria de corpo de prova para ensaio de tracao paralela as fibras da madeira e adotado na NBR-7190 e a proposta de dimensionamento, pelo Metodo Semi-Probabilistico, de uma peca de madeira submetida a tracao paralela as fibras. Exemplo de dimensionamento com dados de resistencia oriundos de pesquisa experimental, nacional e internacional e apresentado.
A good part of the Estrada Real´s bridges, road that goes through Minas Gerais historical region,... more A good part of the Estrada Real´s bridges, road that goes through Minas Gerais historical region, are made by woodand a few of them are found in precarious preservation condition , these bridges need a recorvering that won’talterate their functions and also the historical time they were built up.The research’s main goal is to determine the best solution of the recovery of pathologies found in the constructorsystem used for the most wood bridges from Estrada Real. After analyzing some of the bridges found in Ouro Pretoarea, it was discovered that bridges were executed over circular beams, with 32 cm of average diameter, doublerested,with 11 meters of average gaps and 3 meters of average width. The bridges trays are found in reasonablestate of conservation. The main beams have two pathology types: some were deteriorated by fungus attacks and theothers exhibit excessive deformation of flexure.
Buscou-se, através deste trabalho, fornecer parâmetros comparativos sobre o comportamento mecânic... more Buscou-se, através deste trabalho, fornecer parâmetros comparativos sobre o comportamento mecânico e físico das alvenarias de vedação construídas em blocos cerâmicos vazados e em painéis de concreto celular autoclavado (CCA). Avaliou-se, através de ensaios laboratoriais a resistência à compressão simples e o deslocamento horizontal, a resistência à flexão e o deslocamento vertical ocasionado por esta flexão, a permeabilidade à água e impacto de corpo mole. Investigouse também o comportamento isolado dos dois tipos de argamassa industrializadas usadas nos ensaios-argamassa de assentamento e argamassa colante-de forma a verificarse diferenças significativas que pudessem comprometer os resultados do conjunto. Os resultados do trabalho foram consistentes, apontando para diferenças significativas entre o comportamento dos componentes e os sistemas analisados, tanto nos ensaios individuais, como nos ensaios de paredinhas ou de paredes.
Tropical species are widely used in construction, and their physical and mechanical properties ha... more Tropical species are widely used in construction, and their physical and mechanical properties have been important characteristics with direct impact on the design of structures, especially the strength and stiffness of wood applied in them. Tests to obtain both parameters are conducted under ABNT NBR 7190 (1997) guidelines in Brazil, being rarely found in some research centers because of the higher costs of testing equipment. For instance, the toughness test depends on equipment with a pendulum, whose device requires accuracy and maintenance for reliable analyses. This paper aims to estimate toughness through another property more easily found, given by the compression strength parallel to the grain. For this, 20 tropical wood species of the South American region were used to obtain initial values of these properties. The characteristic values of the compression strength parallel to the grain as well as linear and quadratic regression models were obtained. Statistical analysis was ...
Investigations into the fire resistance of high-strength concrete (HSC) is extremely important to... more Investigations into the fire resistance of high-strength concrete (HSC) is extremely important to optimize structural design in construction engineering. This work describes the influence of polypropylene fibers on the mechanical properties and durability of HSC at high temperatures (25, 100, 200, 400, 600 and 800 °C). HSC specimens with 2 kg/m3 composed of polypropylene fibers are tested in a temperature range of 25 to 800 °C, followed by microstructural analysis. In addition, a statistical analysis is designed to identify the effect of factors, namely temperature and polypropylene fibers, and their interactions on mechanical properties and water absorption, electrical resistivity, mass loss and ultrasonic velocity. Most of the properties are improved by the incorporation of fibers, obtaining highly predictable regression models. However, the polypropylene fibers reduce compressive strength but improve the residual mechanical properties up to 400 °C.
RESUMO A madeira é um excelente material estrutural, além de possuir excelente resistência tanto ... more RESUMO A madeira é um excelente material estrutural, além de possuir excelente resistência tanto à tração como compressão. Para o dimensionamento correto, as premissas da norma brasileira são de estrema valia como norte para os engenheiros estruturais, pois exibe valores padrão de resistência. Dessa forma, esse estudo tem como objetivo analisar se o valor de resistência ao cisalhamento característico paralelo às fibras da classe C60 exibido na norma brasileira confere com os valores obtidos em ensaio de 23 espécies brasileiras, utilizando a metodologia Bootstrap com 1 milhão de simulações. Além disso, buscou analisar, com modelos de regressão, se é possível estimar a propriedade de resistência (fν0) dessas 23 espécies em função da densidade aparente, buscando assim uma obtenção rápida das propriedades dessas espécies com apenas a densidade aparente. Por final, foi possível concluir que a norma brasileira subestima a resistência ao cisalhamento das madeiras brasileiras, apresentado u...
O presente estudo tem por objetivo a análise técnico-econômica de edifícios de 3 a 21 pavimentos,... more O presente estudo tem por objetivo a análise técnico-econômica de edifícios de 3 a 21 pavimentos, com aplicação de distintos valores de resistência característica à compressão aos 28 dias (fck), variando entre 25 e 40 MPa, com relação geométrica, em planta, de 1:4. Estimase que, por meio dos resultados obtidos, seja possível auxiliar a concepção, o dimensionamento e, principalmente, subsidiar a orçamentação da superestrutura de edifícios em concreto armado que contemplem tal relação geométrica. De posse dos resultados, conclui-se que: (I) o aumento do valor do "fck" implica na redução significativa das dimensões dos elementos dos subsistemas verticais e no consumo de aço; (II) para cada caso analisado ("A" até "F"), as espessuras médias dos pavimentos tipo e o consumo de fôrmas se mantiveram praticamente constantes independentes do aumento do valor de "fck"; (III) a composição de custos mostrou que os sistemas dimensionados com concretos de resistência (C-35) geram menores custos globais. Palavras-chave: Concepção estrutural, Consumo de materiais e insumos, estruturas de concreto armado ABSTRACT This study aimed to technical and economic analysis of buildings 3-21 floors, with application of different characteristic values compressive strength at 28 days (fck), ranging between 25
International Journal of Materials Engineering, 2018
Wood has long been used by man for a wide range of purposes, including the production of furnitur... more Wood has long been used by man for a wide range of purposes, including the production of furniture, civil construction and structural elements. Aiming the construction industry, the use of glued laminated timber proves to be an excellent alternative to constructive technology, allowing the production of elements with different shapes and sizes. It is important that the bonded wood presents resistance to the stresses imposed on its use. This way, the present study aims to make a comparative analysis of shear strength values of Glued Laminated Timber (also called glulam) through the analysis of studies done by several authors that used different types of wood and adhesives. The results found by these authors were verified based on the ASTM-D-5751 and the Brazilian standard ABNT NBR 7190. It was concluded that the glued joints analyzed obtained satisfactory resistance according to the American standard. However, the majority did not comply with the parameters required by the Brazilian standard.
International Journal of Materials Engineering, 2018
The three point bending test, according the Brazilian Standard ABNT NBR 7190, enables to identify... more The three point bending test, according the Brazilian Standard ABNT NBR 7190, enables to identify the values of two wood properties: conventional modulus of elasticity and conventional strength on static bending test. With the results, this study aimed to perform a numerical simulation using the finite element software ABAQUS and the experimental results of three point bending test using Simarouba amara Aubl wood specie test proofs. Two analysis were performed, considering wood as elastoplastic material in the first and the second, considering only elastic material. From stress-strain diagrams results, it was observed the evaluation of modulus of elasticity on static bending test is not valid due to material non-linearity. A constitutive model was proposed for Simarouba amara Aubl. wood specie and for evaluation of modulus of elasticity on static bending. It was performed a comparative analysis between experimental results and the proposed constitutive model. These models showed their efficiency when evaluated the normal stress on proof test with demonstrated accuracy, allowing its use by wood structures designers.
International Journal of Materials Engineering, 2017
The purpose of this research is to demonstrate, in an original study, the potentiality of the use... more The purpose of this research is to demonstrate, in an original study, the potentiality of the use of Cajueiro (Anacardium sp.) and Amescla (Trattinikia sp.), two low density tropical wood species, for producing OSB (Oriented strand boards), structural panels that replace plywood for several building purposes. In those panels, wood strands can be disposed in a specific direction or in random distribution, in order to reach the desirable mechanical properties. In this case, the strands were oriented by a separator to generate layers in mass proportion 20:60:20 (outer, inner and outer layers). Then these pre-panels went to a pre-pressing to form the mattress. Finally, they were pressed at 100°C, by 10 minutes, under 4.5MPa pressure, using castor oil based bicomponent polyurethane resin as adhesive. They were produced eight panels (four with Cajueiro e four with Amescla), with nominal dimensions 350mm length, 350mm width and 10mm thickness. Results showed that these wood species can be used to produce OSB, mainly considering values obtained in mechanical tests, that are superior to OSB produced in Brazilian enterprises and can be classified as OSB/4, as recommended by European standard EN 300. Research should continue to be developed in order to reach more adequate performance in swelling and water absorption.
The fiber saturation point (FSP) is an important parameter of wood material, related to dimension... more The fiber saturation point (FSP) is an important parameter of wood material, related to dimensional stability and variations of mechanical performance. This paper investigated the FSP values of 15 tropical Brazilian wood species covering all strength classes of the Brazilian standard code. An additional goal was to estimate FSP value based on the wood’s apparent density. The FSP values were determined by measuring the wood specimen dimensions during moisture content reduction from the saturated state. Wood densities at 0% and 12% moisture contents and basic density were determined according to the Brazilian standard code. The average FSP for all wood species was 21.6% moisture content. Among density values, good correlations were observed, and a multivariate regression model for FSP estimation based on wood densities presented a coefficient of determination equal to 13.07%. There was no correlation between FSP and wood densities, suggesting that this parameter is almost constant reg...
Wood engineered products are alternatives to the use of timber for civil construction, manufactur... more Wood engineered products are alternatives to the use of timber for civil construction, manufacturing, and the furniture industry. One of these products is the medium density particleboard (MDP) panel, which is made of wood particles and resin under high temperature and pressure. This research produced a prototype to evaluate the use of MDP panels waterproofed by castor oil-based polyurethane resin and Pinus sp. residues treated with CCB preservative for use as a wall coating. The influence of weathering, position of wood panel, and waterproof treatment were evaluated. Panels were made under the requisites of Brazilian Standard ABNT NBR 14810 (2013) and evaluated with international standards. MDP panels met standard requisites, with properties similar to that reported in the literature, indicating the possibility of use as wall coating. Statistical analysis indicated the only significant factor was weathering, which influenced physical and mechanical properties.
International Journal of Materials Engineering, 2018
Wood is widely used in many sectors of civil construction as a structural material. Brazilian cod... more Wood is widely used in many sectors of civil construction as a structural material. Brazilian code ABNT NBR 7190:1997 "Design of Timber Structures" governs the method of project design as well as the characterization of wood for structural design. In this aspect the code considers wood as an orthoptic material, however is well known that the organic origin provides great anatomical complexity to its. This work aims to study the distribution of normal stresses in a Tauari wood beam subjected to the elastic regime, and to ascertain the current position of the Neutral Line during test. For this purpose, a four-point static bending test and subsequent compression and tension to the grain tests were performed to determine the modulus of elasticity and calculate the normal stresses by recording deformations and applying Hooke's Law. The data were statistically analyzed to define bests adjusts to Stress vs. Strain diagrams, and thus determine the location of the Neutral Line. It was verified that the position of the Neutral Line was a normal distribution variable, being located at 1,07cm above the geometric center of the board. Finally, the comparison between values of normal tension obtained experimentally and through the theoretical method was determined and similarities were verified in these data, being also plausible the theory for the calculation of the normal tensions of the wood beams, when it is in the elastic regime.
International Journal of Materials Engineering, 2017
The most commons woods used for production of medium density particleboard (MDP) are Eucalyptus a... more The most commons woods used for production of medium density particleboard (MDP) are Eucalyptus and Pinus. The Cajueiro and Amescla wood are typical trees coming from the center-west of Brazil, from the States of Mato Grosso and Tocatins. These are medium density woods similar to Pinus sp, the Brazilian's wood's industries usually used these woods only as piece of wood for structures or furniture. The purpose of this research is to investigate, in a preliminary study, the possibility of MDP panel's production using Cajueiro and Amescla wood species. The panels were produced under a pressure of 4 MPa for 10 minutes at 100°C, and it was produced a total of 12 MDP panels, 6 of Cajueiro and 6 of Amescla, with a thickness of 10mm, dimensions 250mm×250mm and 0.5 kg mass. For the bending modulus of elasticity, 2200 MPa were obtained for Cajueiro and 2700 MPa for Amescla, which are considered good values. The results can be considered satisfactory because it is a preliminary and unpublished study in the case of MDP panels manufactured with Cajueiro and Amescla wood species.
In wood structures, the elements subjected to bending stresses, such as the beams, present a frac... more In wood structures, the elements subjected to bending stresses, such as the beams, present a fracture initiated in the tensile region, and under these conditions, the use of laminated composite materials is presented as an alternative solution in the form of repair or reinforcement. This research aimed to evaluate the influence of the use of carbon fibers laminated composites in tensile reinforcement in the direction parallel to grain of Pinus elliotti and Manilkara huberi wood species. The Viapol two-component epoxy adhesive was used in the lamination and fixation of the unidirectional carbon fiber in the wood species. Ten specimens with no defects (reference) and 10 specimens were prepared for each crack length (25 and 50mm) with and without the reinforcement (60mm × 50mm) by the laminated composite. The tensile tests were performed in accordance with the requirements of the Brazilian standard ABNT NBR 7190 (1997). From the results of the statistical analysis, the use of the carbon fiber composite was able to restore the tensile strength of the cracked samples (partial or total) in relation to samples without defects, demonstrating the potential of the laminates in carbon fibers as an alternative solution in repair for both wood species.
International Journal of Materials Engineering, 2018
The study of pull out strength of glued in rods perpendicularly to the grain is presented. Three ... more The study of pull out strength of glued in rods perpendicularly to the grain is presented. Three types of resin were used in order to evaluate their efficiency. Additionally, the effects of the variation of the moisture content and of the glue line thickness were considered. The beams were made of wood from Corymbia citriodora, (ρ 12% = 1000 kg/m 3) and Pinus oocarpa Shiede (ρ 12% = 550 kg/m 3). The wood specimens (four samples for each type of test) were seasoned to the expected moisture contents of 12, 15, 18 and 22%. The anchorage length of the glued in rods was 80 mm, the hole diameters were 7.5, 8.5, 9.5 and 10.5 mm and their respective glue line thickness, 0.6, 1.1, 1.6 and 2.1 mm. The deformed reinforcing bars used as rods, with the minimum yield strength of 500 MPa, had nominal diameter of 6.3 mm. The obtained results confirmed the assumption that type of resin, moisture content, glue line thickness are strength determining factors, while density is less than others. The results are presented in a comparative form. The failure modes are discussed and the need of a broad understanding of resin behavior on wood was emphasized.
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Papers by Eduardo Chahud