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Wood, due to its complex anatomy, requires meticulous characterization that imposes several tests to be carried out to evaluate its properties. Normative codes adopt different specimens to this aim. Geometric specificities proposed by NBR 7190-3:2022 and ASTM D143-22 to specimens used for estimating wood strength in tensile perpendicular to grain (ft90) make them difficult to carry out. Thus it is advisable to consider relating ft90 with another mechanical property, for example, the shear strength parallel to the grain (fv0). This paper aims to establish a coefficient relating the characteristic values of ft90 and fv0, for strength classes D40 and D60 (frequently used for structural purposes) of Brazilian Code 7190:3-2022. A further aim, if possible, is to determine a single representative coefficient for both classes. Tests made it possible to obtain those properties for four species from each class, following NBR 7190-3:2022 guidelines. The optimal coefficient was determined using the least squares method (MMQ). Ratios ft90,k/fv0,k were 0.22 and 0.19, for classes D40 and D60, respectively. As these ratios don’t present a significant difference, it is viable to adopt a single relationship for both classes, thus simplifying characterization procedures.

Particleboards find extensive application in both civil construction and the furniture industry. Nevertheless, concerns about the interaction of panels with humidity require the exploration of alternative sources to develop a product that meets the requirements for use. This work aims to produce single-layer particleboards with coconut fiber (Cocos nucifera) as substrate, bonded with 10% by mass castor oil-based polyurethane resin (CPUR). Two groups of mixtures were proposed, different from each other in the initial moisture content of the Cocos nucifera particles, ranging from 0 to 2% and from 4% to 6%. For this purpose, density (D), thickness swelling after 24 h (TS), moisture content (MC), and water absorption (WA) were evaluated. The Tukey mean contrast test, at a 5% significance level, was used to verify the influence of the initial moisture content of the particles on the physical properties of the particleboards. The microstructure of the composites was assessed through the utilization of scanning electron microscopy (SEM) technique. The results indicated better compaction of the C. nucifera particles, resulting in fewer voids, contributing to the densification of the panels and, with this, the reduction of water absorption by 15.1%.

Tensile perpendicular to grain is an important mechanical property in the design of joints in timber structures. However, according to the standards, this strength can be determined using at least two different methods: uniaxial tensile and three-point static bending. In this context, the present paper aims to investigate the influence of these test methods on the determination of tensile strength perpendicular to grain of wood used in civil construction timber. Three wood species from Brazilian planted forests (Pinus spp., Eucalyptus saligna, and Corymbia citriodora) were used in this investigation. Twelve specimens of each species were used for each test method investigated. Moreover, a statistical analysis was performed to propose an adjustment to the equation of the Code of International Organization for Standardization 13910:2014 for the three-point bending test. Tensile strength values perpendicular to grain obtained from the uniaxial tensile test were significantly higher than those determined by the three-point bending test. It is proposed that the tensile strength perpendicular to grain can be determined more precisely with adoption of coefficient 5.233 in the term [(3.75·Fult)/b·Lh] of the equation specified by the Code of International Organization for Standardization 13910:2014 for the three-point bending test.

Eucalyptus-based glued laminated timber (glulam) was produced to determine the feasibility of a non-destructive method (drilling resistance) to predict the properties of structural elements and add value to lower-quality hardwood species. Glulam was manufactured with formaldehyde (Resorcinol), reference condition, and bio-based (Castor oil-based) adhesives in two assembly schemes, the core composed either of two continuous lamellae each 105 cm long, or of two formed by the juxtaposition of shorter boards (35 and 55 cm). The shear strength of the glue line (fv0), modulus of elasticity (Ec90), and strength (fc90) in compression perpendicular to the grain; delamination (DL); and main and extended glue line thicknesses were evaluated. The Resistograph equipment was used to perform the perforation perpendicular to the glue line (samples extracted from the glulam elements) to correlate the properties. The results of this research demonstrate that the scheme of the boards had little effect on the physical and mechanical properties evaluated (except the main glue line and delamination), and the drilling resistance (DR) presents a significant correlation with practically all properties evaluated (variations in density values and other properties are explained by variations in DR values), making it possible to estimate Ec90 and fc90 with desired precision (R2adj ≈ 80%). This highlights the feasibility of using this methodology in the quality control of glulam elements. It is concluded that regardless of the adhesive, elements comprising a 105 cm-length core and external lamellae (T1 and control) are indicated for external use, presenting low delamination. Short-length central lamellae adhesively glued with PUR (T2) are not recommended for external applications due to their susceptibility to delamination. However, T2 is indicated for internal environments due to its low production cost. This study also proved the efficiency of using models based on drilling resistance to estimate wood density and its resistance to compression perpendicular to the fiber.

Despite the extensive research on renewable resources (RR) and their potential applications in composite materials and sandwich structures, there remains a significant dearth of life cycle assessment (LCA) studies that comprehensively evaluate the efficacy of RR in mitigating environmental impacts (EI). To bridge this gap, the present study aims to investigate twelve different designs of sandwich panels, specifically referred to as Fibre Metal Laminates (FML). These FML combine aluminium skins (2024-T3 and 1200-H14), polymer matrices (Epoxy, Polyester, and Castor oil Bio-PU), natural fibres (Sisal, Coir, and Cynodon spp.), surface treatments for aluminium skins (sanding, NaOH, and Washprimer), and treatments for natural fibres (Ground, NaOH-treatment and untreated). A cradle-to-gate LCA is conducted, and the inventories are modelled using the OpenLCA 1.6.3 and ecoinvent 3.9 cut-off regionalized database. EI are evaluated in twelve categories, including climate change, fossil and nuclear energy use, freshwater (acidification, ecotoxicity and eutrophication), human toxicity (cancer and non-cancer), mineral resources use, ozone layer depletion, particulate matter formation, photochemical oxidant formation, and terrestrial acidification. Impact World+ method for Latin America version 1.251 is employed to calculate EI. Nine Eco-efficiency indicators and trade-off analyses are evaluated to gain insights into design decision outcomes. Among the various panels considered, FML12, manufactured with aluminium alloy 1200-H14 treated only with sanding, castor oil biopolymer and untreated coir fibres, present the most consistent eco-efficiency indicators. The reference scenario considers the average characteristics of FML (both environmental and mechanical) for trade-off analysis. Despite the fifty percent chance of better performance, FML12 is the only panel that shows higher mechanical performance and lower EI compared to the reference scenario. The importance of this article lies in the novel results obtained using the proposed eco-efficiency indicators, which can be expanded in further studies on the topic.

To reduce dependence on wood and deforestation, alternative materials have been considered. This research evaluated particleboards panels of Pinus elliotti mixed with residues of polyethylene terephthalate (PET) in flakes with 50% of each material, glued with 10% of castor oil-based polyurethane resin (PUR). The temperature during board production was varied to evaluate its influence on the physical and mechanical properties of the boards. The study concludes that the increase in temperature did not result in a significant improvement in the particleboard properties, but their results showed application potential according to the normative standards.

O resíduo florestal é todo e qualquer material que resulta da colheita ou do processamento da madeira que possa permanecer sem utilização definida no processo. As cinzas advindas da queima de carvão têm sido amplamente utilizadas em pesquisas; trabalhos com o uso de cinzas de biomassa, no entanto, ainda são recentes. O objetivo desta pesquisa consistiu em verificar a viabilidade da inserção de cinzas no traço de um compósito cimento-madeira. Foram realizados testes físicos para a determinação das propriedades físicas, densidade, inchamento e absorção de água, sendo também avaliadas a inibição do cimento com os materiais adicionais e a temperatura de hidratação da mistura. Para as cinzas, foram realizados testes para a obtenção do seu teor, avaliação da composição química, análise da distribuição granulométrica e espectroscopia de infravermelho com a transformada de Fourier (FTIR). A mistura com a cinza apresentou resultado superior em relação à mistura sem a cinza, nas propriedades de densidade e inchamento, dando indícios de que a utilização da cinza de biomassa é recomendada na fabricação de materiais cimentícios compósitos com resíduo de madeira, pois pode contribuir com menor degradação do material, que será avaliado em testes de durabilidade na sequência deste estudo.

Carbon fiber-reinforced polymer (CFRP) sheets have been used to reinforce cross-laminated timber (CLT)–concrete systems in recent years. The existing studies have indicated that the use of CFRP rebars as shear connectors in CLT–concrete panels can improve the structural performance of these elements. However, the application and understanding of CFRP rebars as shear connectors still need to be improved, since comprehensive studies on the subject are not available. Therefore, this research aimed to evaluate the structural performance of CLT–concrete panels with CFRP rebars as shear connectors through finite element (FE) numerical simulation. A parametric study was conducted, varying the connector material, the number of CLT layers, the connector insertion angle, and the connector embedment length. According to the results, panels with CFRP connectors showed a higher maximum load, bending strength, and maximum bending moment than panels with steel connectors. The regression models revealed that the parameters analyzed explained between 80.2% and 99.9% of the variability in the mechanical properties under investigation. The high explanatory power (R2) of some regression models in this study underscores the robustness of the models. The number of CLT layers and the connector material were the most significant parameters for the panels’ maximum load, displacement at the maximum load, ductility, bending strength, and maximum bending moment. The number of CLT layers and the connector insertion angle were the most significant parameters for the panels’ effective bending stiffness. This research highlights the importance of studies on CLT–concrete composites and the need to develop equations to estimate their behavior accurately. Moreover, numerical simulations have proven very valuable, providing results comparable to laboratory results.

Particleboards have gained attention in the global market. Understanding their physical–mechanical behavior in the current technological context is essential due to adhesive polymerization, which depends on variables such as pressing time and temperature. Today, the use of nanoparticles has become a plausible option for improving the properties of polymers used in wood-based composites. This study evaluates the influences of the addition of non-commercial 0.5% aluminum oxide (Al2O3) and aluminum oxide copper (CuO) nanoparticles using a greener route with a lower environmental impact obtaining a urea-formaldehyde (UF)-based polymeric adhesive to manufacture particle composites of Eucalyptus urophylla var. grandis wood. Regarding characterizations, the resin properties analyzed were viscosity, gel time, and pH, as well as panel properties, including density, moisture content, thickness swelling, modulus of elasticity, modulus of rupture, and thermal conductivity. The results were compared with scientific publications and standards. The addition of nanoparticles interfered with viscosity, and all treatments indicated a basic pH. It was not possible to determine the gel time after 10 min. Nanoparticles added to the polymers in the internal layer did not cause an improvement in the swelling properties in terms of thickness, with no significant statistical difference for density and moisture content. The increase from 150 °C to 180 °C may have caused an improvement in all physical–mechanical properties, indicating that the higher temperature positively influenced the polymerization of the formaldehyde-based adhesive. Therefore, the additions of both nanoparticles (0.5% in each condition) led to a limitation in the material influence with respect to physical–mechanical performance.

As a biodegradable material, wood is subject to deterioration if proper conservation techniques are not observed. Thus, several buildings, especially those of historical heritage, present pathological manifestations that can cause accidents. The interventions in these constructions must be planned to maintain the original elements and the aesthetics of the environment, with the indication of fixing additional elements in the degraded structure. The modification of the section of structural elements is commonly observed in the literature; however, few studies have been intended to analyze the effects of reinforcement in these geometrically discontinuous elements. Furthermore, the use of screwed steel plates guarantees greater ease of execution, even though it is not yet a method that has been well explored in the scientific literature. The objective of this study was to propose an equation for estimating the flexural stiffness of wooden beams with loss of cross-section that are then reinforced with screwed steel plates using a regression model. The considered variables correlated the elastic modulus of the wood and the reinforcement, the configuration of the defect, and the reinforcement. It was possible to identify that the properties of the wood and the position of the defect were variables with a significant impact on the stiffness of the reinforced beam.

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.

Estruturas mistas de madeira-concreto unem as melhores qualidades da madeira e do concreto, resultando em estruturas mais leves, rígidas e resistentes. São utilizadas na restauração de pisos e pontes de madeira, bem como na construção destas, em que se percebe um aumento da utilização desse sistema estrutural. Todavia, ainda são poucas as informações referentes às estruturas mistas em madeira-concreto na literatura, e o seu dimensionamento é abordado apenas pela normativa europeia Eurocode 5 (CEN, 2004). Nesse contexto, este trabalho apresenta as principais considerações a respeito do dimensionamento desse sistema estrutural e as principais divergências no emprego de tal técnica, essencialmente no Brasil, considerando a normativa brasileira em estruturas em madeira, para um eventual acréscimo sobre estruturas em madeira-concreto na ABNT NBR 7190 (ABNT, 1997). Ao final, é possível concluir que alguns ensaios padrões precisam ser normalizados para a implementação do dimensionamento dessa estrutura mista na norma brasileira, como por exemplo o ensaio do módulo de deslizamento do conector.

Os sistemas de fundação profunda, muito utilizados para transmitir as cargas provenientes da superestrutura para o solo, são usualmente constituídos por estacas e por um bloco de coroamento, que solidariza e transmite os esforços dos pilares para as estacas. Este trabalho realizou uma análise de sensibilidade de parâmetros, com o objetivo de verificar qual a influência desses parâmetros nos recalques e tensões no topo e na base do bloco. A análise considerou dois blocos quadrados de quatro e nove estacas, nos quais foram avaliados os seguintes parâmetros: altura do bloco, tipo de solo, e quantidade e comprimento das estacas. Os resultados colhidos das simulações foram os deslocamentos no topo e na base dos blocos e das estacas, bem como as tensões normais que surgiram nesses elementos. Foram adotadas medidas de altura do bloco acima e abaixo do critério de bloco rígido, e as estacas utilizadas foram de seção quadrada com 40 cm de lado. A análise estatística dos resultados mostrou que o tipo de solo foi o parâmetro que mais afetou os recalques dos blocos, seguido pelo comprimento e pelo número de estacas. A altura do bloco praticamente não teve influência nos deslocamentos obtidos.

High-strength concretes (HSC) have been widely applied in civil construction. However, this material does not perform well in fire situations due to spalling, a phenomenon that can be significantly mitigated by adding synthetic fibers to HSC cementitious matrix. Estimating HSC physical and mechanical properties for different compositions and temperatures can therefore be useful, as the structure may be pre-designed without requiring prior material characterization in a fire situation. With this perspective, this paper aimed to propose regression models to estimate eight properties of High-Strength Concrete with Polypropylene Fibers (HSC-PPF), namely compressive strength, tensile strength, static modulus of elasticity, dynamic modulus of elasticity, ultrasonic pulse velocity, electrical resistivity, water absorption, and weight loss, at high temperatures (up to 800 °C). For this, it was evaluated the effective correlation between mechanical responses and independent variables, such as temperature, water absorption, and dynamic modulus, and the accuracy of regression models was assessed. The results obtained indicated that, among the models proposed, the two multiple regressions were better than the simple one for estimating HSC-PPF properties since they presented high adjustments (R2) and low mean absolute percentage (MAPE), and coefficient of variation (CV) errors. This methodology can be used in a wide variety of fiber-reinforced HSCs.

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 performed and confirmed that a linear model gave better predictions than a quadratic model.

In order to contribute to the dissemination of lignocellulosic residues in the composite materials manufacturing, this study aimed to investigate the influence of a soaking in the presence of natural bacteria and fungi on the resistance to axial traction of açaí fibers (Euterpe oleracea Mart.). The stipulated factors and levels were the source of water, i.e., Rio Guamá, Pará Sanitation Company COSANPA and Cassava, as a catalyst and the mass concentration of water on the açaí cores, i.e., 2%, 4%, 6%. In this way, 9 different experimental conditions were performed, together with the reference condition, i.e., açaí fibers without the soaking. In all, 200 specimens were cast, with 10 of each composition. The analysis of variance results revealed that the individual factors were not significant in obtaining the axial tensile strength, providing equivalent results regardless of the concentration and type of water. However, the interaction between the factors was considered significant, showing that the best treatment for the fibers came from the use of 2% cassava scraps. The axial tensile strength was 47% greater than the axial tensile strength obtained from the reference sample. Furthermore, 59% surpassed the reference sample, showing the efficiency of the soaking in the presence of natural bacteria and fungi treatment.

Microwave (MW) drying of wood has gained popularity in the field of wood modification. The rise in temperature during MW drying leads to increased steam pressure, enhancing wood permeability but potentially decreasing mechanical properties. Understanding temperature and moisture behaviors during MW drying is crucial for its industrial application in wood drying. Therefore, this study aimed to characterize the temperature and moisture behaviors during MW drying of small Portuguese maritime pine (Pinus pinaster Aiton.) wood samples to support a wider use of this technology. The effects on water uptake and the compressive strength parallel to the grain were also investigated. The results indicated three distinct phases in the MW drying rates, with an average of 0.085% of water removed per second. Moreover, the temperature underwent three distinct stages: an initial rapid increase, a period of constant temperature, and a slight decrease until drying was complete. At the beginning of MW drying, the temperatures were below 100 °C, with average temperatures ranging from 126 to 145 °C. Specimens with lower initial moisture content had higher temperatures, and a positive correlation was found between initial moisture content and drying time. In contrast, negative correlations were found between the initial moisture content and average temperature, as well as average temperature and MW drying time. Additionally, the operating condition parameters used in MW drying of pine samples enhanced water impregnability by 65%, generating a slight reduction of 11% in compressive strength. It was also noticed that the initial moisture content did not impact MW-dried samples’ water uptake or compressive strength. Finally, although small clear wood samples of maritime pine were utilized, the temperature and moisture patterns observed closely matched real-scale specimens. Thus, the findings corroborate a wide utilization of MW technology for wood drying, mainly demonstrating positive possibilities for structural-sized wood specimens.

Bamboo is already a convenient construction resource, as it offers an efficient structural performance. As this plant has native varieties adapted to different climates and soils of Brazil, bamboo silviculture can be intensified to supply the national industry. Three bamboo species from Brazil (Dendrocalamus asper, Bambusa tuldoides, and Phyllostachys aurea) were analyzed for the flexural load capacity applied on the internal and external surfaces. Specimens were prepared without knots and with knots centered at the middle of each sample. In total, 240 samples were tested in terms of static bending and dynamic bending (impact). The results showed a higher flexural elasticity and a higher proportional limit strength of knotted P. aurea. The presence of knots provided higher values of ultimate strength in P. aurea, even reducing the bamboo flexibility. Also, P. aurea exhibited the best characteristic of flexural dynamic energy absorption among the three bamboo species under evaluation.

A caracterização não destrutiva é uma das opções para determinar as propriedades dos materiais sem que estes sejam inutilizados posteriormente, geralmente determinando suas propriedades dinâmicas. Para que essas propriedades sejam relacionadas com as estáticas, faz-se necessário o uso de modelos matemáticos de predição. Contudo, a calibração desses modelos varia de acordo com o material considerado e requer a realização de ambos os tipos de ensaio: destrutivo e não destrutivo. O presente trabalho teve como objetivo propor modelos de correlação entre resistência e rigidez na flexão estática de compósitos do tipo OSSB (Oriented Structural Straw Board) a partir de sua densidade aparente e frequência de vibração, sendo esta obtida com a técnica de excitação por impulso. Foram caracterizadas placas de OSSB fabricadas com palha de soja e adesivo poliuretano à base de óleo de mamona em quatro porcentagens de adesivo, sendo estas: 6%, 9%, 12% e 15%. Os modelos de regressão múltipla propostos apresentaram boa precisão (R² > 80%) em predizer as propriedades mecânicas na flexão, sendo que o estimador da densidade foi o mais significativo. Observou-se também que o aumento do teor de adesivo nas chapas provocou melhora significativa no desempenho mecânico do material.

A utilização de sistemas de reforço tem se tornado uma solução comum para as inúmeras formas de degradação e deterioração dos elementos estruturais. Entre os diferentes tipos existentes, neste trabalho, certa ênfase foi dada às técnicas de encamisamento, chapas de aço e EBR (Externally Bonded Reinforcement) com polímeros reforçados com fibras de carbono (CFRP – Carbon Fiber Reinforced Polymer). Objetivando a avaliação dos incrementos de resistência resultantes, um software foi desenvolvido, com base nas normas técnicas vigentes. Para tal, incrementos graduais de 10% foram dados a uma força concentrada F de uma viga de concreto armado simplesmente apoiada. Os resultados evidenciaram que em até 40% de aumento de F, a técnica EBR com CFRP apresentou incrementos de resistência superiores. Já com 50% de acréscimo de F, a técnica de encamisamento se sobressaiu. Entretanto, em todas as porcentagens de aumento de F, o rendimento da técnica EBR com CFRP se mostrou bastante superior ao das demais, haja vista que possui incrementos de resistência significativos, associados a um reduzido volume de material. Diante dos apontamentos expostos, evidencia-se que a aplicação de CFRPs pela técnica EBR configura-se como uma excelente solução de reforço estrutural, apresentando rendimentos significativos e interferências arquitetônicas quase nulas, devido ao seu reduzido volume de material.

Os compósitos madeira-cimento são formados por uma mistura de cimento Portland, água e resíduos de madeira em fibras ou partículas, aplicando-se principalmente em painéis, obtendo-se um destino aos resíduos da indústria madeireira. Fatores como a espécie, tratamento e dimensão das partículas de madeira interferem no desempenho físico e mecânico dos compósitos e por isso são continuamente investigados na literatura. Dessa forma, nesse trabalho apresentou-se uma análise físico-mecânica experimental de compósitos madeira-cimento com resíduos de Pinus sp. e bambu da espécie Dendrocalamus giganteus tratados em água quente e analisou-se seus efeitos na densidade, o módulo de elasticidade e o módulo de ruptura obtidos através de ensaio de compressão. Avaliou-se, também, a aplicação de modelos micromecânicos (regras de mistura) na predição do módulo de elasticidade. Por fim, os resultados experimentais foram analisados estatisticamente e o módulo de elasticidade obtido pelos modelos micromecânicos foram comparados aos obtidos experimentalmente.

Cantoneiras enrijecidas de aço formadas a frio podem apresentar três modos críticos de instabilidade. Entretanto, barras em seção composta podem apresentar outros modos de acordo com o tipo, a disposição e a configuração das conexões. Barras compostas em dupla cantoneira com travejamento em quadro são constituídas por duas seções idênticas, dispostas de forma paralela e ligadas, em apenas alguns pontos ao longo do seu comprimento, por chapas separadoras. Apesar de ser um sistema bastante utilizado, não existem especificações nas normas para dimensionamento preciso desse componente estrutural. Posto isso, este trabalho objetivou avaliar a influência da inserção de travejamentos ao longo do comprimento na força normal resistente das barras compostas e verificar se os resultados obtidos estão compatíveis com os das hipóteses adotadas com base nos procedimentos normativos. Para tanto, foi realizada uma análise numérica não linear pelo Método dos Elementos Finitos no software Ansys, utilizando-se seções caracterizadas experimentalmente e disponíveis na literatura. Nesse sentido, observou-se que a adição de chapas separadoras aumentou significativamente a força normal resistente dos elementos, sendo os arranjos com uma ou duas chapas os mais efetivos. Os resultados foram intermediários, considerando as normativas adotadas, e indicaram a necessidade a necessidade de um modelo de cálculo próprio para o arranjo de cantoneiras enrijecidas compostas, ligadas por travejamentos em quadro.

A construção civil é um dos setores da economia que mais demandam matérias-primas; além disso, diante de cenários de baixa qualidade na execução de obras, ela também é conhecida pela geração dos Resíduos de Construção e Demolição (RCD). Diante disso, o objetivo desta pesquisa é estudar a influência da utilização de agregado reciclado misto à base de RCD, em diferentes teores de substituição, em relação ao agregado natural na resistência à compressão e na porosidade de argamassa no estado endurecido. Foram estabelecidas três diferentes formulações: uma de referência sem resíduo; com 50% de substituição do agregado natural e; com 100% de agregado reciclado. Observou-se que as argamassas com teores de resíduos incorporados demandaram maiores quantidades de água que a argamassa de referência para o mesmo nível de consistência. As argamassas apresentaram valores de resistência à compressão que permitem sua utilização para assentamento e revestimento de paredes e tetos, de acordo com a norma NBR 13251/2005. Em relação à porosidade, quanto maior o teor de resíduo, maior a porosidade da argamassa. Conclui-se com esta pesquisa, a viabilidade técnica da utilização de agregados miúdos à base de resíduos da construção e demolição para fabricação de argamassa.

A cadeia produtiva da madeira sólida gera grande quantidade (60%) de resíduos, que, alternativamente ao descarte e à queima, podem ser utilizados na fabricação de outros produtos, como painéis particulados. Dessa forma, esta pesquisa objetivou, com o uso do mix de maravalhas na forma integral de madeiras de Pinus elliottii e Pinus taeda e do adesivo ureia-formaldeído, avaliar as propriedades físicas dos painéis gerados com partículas de diferentes densidades, além de estimar propriedades em função de outras, através de modelos de regressão lineares, considerando também parâmetros colorimétricos. Foram produzidos seis painéis de partículas de média e seis de alta densidade. As propriedades foram obtidas de acordo com as premissas e métodos de cálculo da norma brasileira ABNT NBR 14.810-2:2018, sendo os requisitos avaliados com base em normas brasileiras e internacionais. De acordo com os resultados obtidos, verificou-se que a densidade dos painéis afetou, significativamente, em praticamente 50% as propriedades determinadas. Os painéis podem ser classificados como P2 pela norma brasileira, cabendo destacar que, em algumas propriedades, os valores superaram os requisitos da classe P7. A condutividade térmica indica ser apropriada a aplicação dos compósitos em edificações. Dos modelos de regressão, apenas quatro apresentaram coeficiente de determinação ótimo.

Devido às suas vantagens, a madeira tem sido amplamente utilizada como elemento estrutural ao redor do mundo, principalmente em países do Hemisfério Norte. Entretanto, no Brasil, apesar de sua expressiva diversidade florestal, muito pouco desse potencial é utilizado, devido a preconceitos contra o material. Todavia ainda se verifica a recorrência de seu uso em estruturas treliçadas planas de telhados. Uma das problemáticas que envolvem o projeto de estruturas de cobertura é aquela referente aos modelos idealizados de análise. Engenheiros projetistas costumam adotar o modelo clássico de treliça na concepção estrutural. Entretanto, ao se considerar outras modelagens, diferenças significativas podem ser observadas nas dimensões finais das peças. Sendo assim, priorizando a avaliação dessas influências, uma ferramenta computacional foi desenvolvida baseada no método dos elementos finitos (MEF) e nas rotinas de dimensionamento prescritas pela revisão da NBR 7190 (ABNT, 2020). Os valores de esforços e deslocamentos foram aferidos com o software SAP2000®, resultando em notória confiabilidade. Mediante fixação da espessura, o critério de dimensionamento utilizado foi o de altura mínima dos perfis. Após simulação de três modelos idealizados, os resultados evidenciaram que os perfis realmente sofrem consideráveis mudanças em função do modelo empregado, atingindo dimensões cerca de 50% inferiores em modelos que conferem rigidez perfeita.

ABSTRACT To simplify the characterization of wood species, the Brazilian standard document ABNT NBR 7190-1 (2022) establishes the determination of mechanical properties employing the characteristic strength in the compression parallel to grain (fc0,k). This mechanical property is estimated using the linear relation given by the following expression fv0,k = 0.12·fc0,k Brazilian and European standard documents support the estimation of fv0,k using relations among properties. However, the European guidelines in the EN 384 (2019) have used the conventional characteristic strength in the static bending test (fM,k). Thus, this study aimed to investigate the efficiency of the ratio fv0,k = 0.12·fc0,k for adopting 30 hardwoods. The variance analysis results demonstrate the divergence among the experimental outcomes and those values estimated using the relation cited. Therefore, regression models at two parameters were considered to obtain more accurate estimates of fv0,k by adopting fc0,k, and fM,k as independent variables. Regarding the results, the geometric (R² = 80.80%) and linear (R² = 74.19%) models were the most accurate for the estimates of fv0,k in terms of fc0,k, and fM,k, respectively. This fact evinces the good accuracy of the models under consideration, which may provide a more rigorous structural design compared to the correlation currently prescribed by the ABNT NBR 7190-1 (2022).

Timber housing is a sustainable bioresource-based alternative to traditional construction with masonry and steel, and recent studies have shown that this sector in Brazil has hundreds of timber housing SMEs. This exploratory study, while analyzing this population, evaluated the profiles available on Instagram®, observing their business strategies and what they have disclosed to clients on sustainability benefits and issues. All the available corporate profiles were surveyed, and a significant sample of about 80% of a sector was compiled, from a market currently formed by over 400 companies. However, about 70% of these Brazilian companies still do not adequately explore sustainability issues in their timber housing products and service, evidencing an incipient scenario. Moreover, there is a clear opportunity to leverage the arguments posted on their Instagram® profiles as an affirmative awareness strategy. Although some justifications were suggested to convince domestic customers to consider timber housing, this virtual market has a lot of room for improvement.

This work describes the correlations between the ultrasonic pulse velocity (UPV) and physical properties of fibrous-particulate hybrid composites made of glass/carbon fabrics and three different micro-inclusions such as silica particles, recycled carbon fibre powder and Portland cement. A full factorial design (214151) is established to identify the effects of volume fraction, stacking sequence and particle type on the physical properties obtained by Archimedes’ principle. An electroacoustic transducer (50 ​kHz) is used to determine the ultrasonic pulse velocity data. Statistical models reveal correlations between UPV and the physical properties of hybrid composites. The combination of UPV and statistical techniques can identify all constitutive phases, being useful to characterise and estimate physical properties in a hybrid system composed of fibres and microparticles.

Abstract In order to evaluate the influence of moisture content on wood physical and mechanical properties, the present research analyzed the influence of moisture content variation on Cedrella sp. on 12 strength and stiffness properties, considering 12% moisture content up to Fiber Saturation Point (FSP) were considered. Brazilian Standard consider a correction on wood properties obtained on moisture content different of 12%, reducing the properties. Eight properties from these twelve were significantly influenced by moisture content according to statistical analysis (5% significance level). ANOVA, Anderson Darling and Multiple Comparison tests were used at 5% significance level. Considering that most of properties were affected by moisture content, the equations to estimate wood properties according to moisture decrease are quite precise, but most of estimations were higher than the experimental values at 12% moisture content, indicating the need of a standard review for such estimators, which may lead to an unsafe timber structure design. For a conclusive consideration of moisture content variation influence on wood products, further researches with other tropical wood species are required.

Eucalypts have not been well accepted for construction use by civil societies in different nations. For the elimination of these cultural barriers, there is the demand for better knowledge of the physical-mechanical properties of these silvicultural species. Thus, the research carried out a wide characterization of the Eucalyptus paniculata Smith wood species. Based on the Brazilian standard document ABNT NBR 7190, 14 mechanical properties and 2 physical properties were evaluated. Two moisture contents were adopted to compare the wood samples in different conditions: above the fiber saturation point and dried point. Results of properties were treated statistically with a t-test. In total, 1384 repeats were reached. Only two mechanical properties did not show changes in their resistance values to moisture reduction: tangential cleavage and modulus of rupture in the perpendicular tensile to grain. Further properties showed differences in the resistances from t-test for the studied moisture reduction.

The Concrete Damage Plasticity (CDP) model is a widely used constitutive model to represent the non-linear behavior of concrete in numerical analysis. However, a limited number of studies compared the level of accuracy of numerical models with the main code provisions from the literature. In addition, the influence of CDP material parameters on the structural behavior of corbels was scarcely studied. This study proposes to evaluate the ability of numerical models using CDP to represent the structural behavior of corbels regarding the ultimate load, reinforcement deformation and failure mechanism. In addition, we compared the predictions of the numerical models with the ones from design code expressions regarding the ultimate capacity. For this, three test results of corbels from the literature were evaluated with numerical models using the CDP, as well as with analytical models from different code provisions. A sensitivity analysis—by changing the dilation angle (ψ) and shape factor (Kc)—was performed. The comparison between tested and predicted resistances with the proposed numerical modeling choices was equal to 1.04 with a coefficient of variation of 11%. On the other hand, the analytical models evaluated overestimated the corbel capacity by more than 62%, on average. Therefore, the proposed modeling choices provide better predictions of ultimate capacity than the evaluated analytical models and can be used to assess the corbel design under more complex boundary conditions.

Os painéis de partículas utilizados neste estudo foram fabricados com resíduos de madeira de Eucalyptus sp. e Pinus sp., previamente tratados com produtos preservantes CCA, CCB e resina poliuretana à base de mamona. Os corpos de prova extraídos dos painéis foram expostos ao intemperismo natural de acordo com as recomendações da norma D1435 (ASTM, 1994), nas seguintes condições: “in natura” (sem revestimento) e revestidos com resina poliuretana à base de óleo de mamona. Foram analisados lotes de corpos de prova não expostos ao intemperismo (referência) e em diferentes períodos de exposição (3, 6, 9 e 12 meses), entre dezembro de 2014 e dezembro de 2015, no município de São Carlos, interior do estado de São Paulo. Os resultados do teste de Tukey evidenciaram reduções significativas nos valores dos módulos de elasticidade e de resistência na flexão estática e da resistência ao arrancamento de parafuso de topo para os materiais envelhecidos; entretanto, o mesmo não ocorreu com a adesão interna e a resistência ao arrancamento de parafuso de face, que, para alguns tratamentos, apresentaram valores superiores aos painéis fabricados da condição de referência.

Neste trabalho foi analisada a variação dos esforços resistentes de vigas de madeira em situação de incêndio. Foram verificadas vigas de madeira folhosa com seção transversal retangular, divididas em dois grupos, sendo o primeiro constituído por vigas de madeira serrada e o segundo, por vigas de madeira laminada colada (MLC). Para efeito de comparação, variou-se a resistência à compressão paralela às fibras da madeira folhosa, considerando, ao todo, quatro classes de resistência: D30, D40, D50 e D60. Em todos os casos foi considerada a taxa de carbonização de 0,55 mm/min, associada a madeiras de média e alta densidade, segundo as normas técnicas de dimensionamento. Além disso, nenhuma proteção térmica foi adotada. Observou-se que o tempo máximo de resistência ao fogo foi de 40 minutos para as vigas de madeira serrada e de 120 minutos para as vigas de MLC. A variação dos esforços resistentes em função do tempo foi aproximadamente linear para a força cortante, enquanto o momento fletor apresentou variação ligeiramente não linear. A variação da classe de resistência da madeira promoveu diferenças proporcionais nos esforços resistentes.

Neste trabalho apresenta-se uma metodologia para análise não linear geométrica de sistemas treliçados planos de madeira, a partir de uma formulação posicional do método dos elementos finitos. Dois modelos de treliça são analisados e madeiras folhosas com classe de resistência C60 são consideradas na composição das barras. A formulação do elemento finito é realizada a partir da minimização da energia potencial total, cujo sistema de equações é não linear em relação às posições nodais da estrutura e sua resolução é alcançada empregando o método de Newton-Raphson. Os resultados obtidos são comparados aos de uma análise linear geométrica para cada modelo, sendo possível observar que esta análise (linear) pode conduzir a valores inferiores de esforços internos e deslocamentos, o que influencia a etapa de dimensionamento e eventualmente pode oferecer riscos à segurança estrutural. Conclui-se que o emprego de análise não linear geométrica deve ser priorizado no projeto de treliças de madeira, mesmo que isso implique em maior custo computacional e complexidade envolvida no procedimento de análise.

This paper has developed a model to perform more sustainable scheduling in manufacturing operations based on the combination of makespan, profit margin, and environmental impact indicators. A case study was designed to run the developed model in the production of automotive identification labels. The proposed model combined the NEH heuristics for a flow-shop production scheduling problem followed by the cradle-to-gate Life Cycle Assessment of the labels, in order to find scheduling solutions for minimising major environmental impacts and aggregate more value to the production flow. The main results showed that the proposed model was able to increase the company’s schedule performance. For the scenario analysis, two-hybrid heuristics were compared: NEHS-1 and NEHS-2, and both showed better schedule results than the classical NEH. However, the best results were presented by the NEHS-2, and it should be further improved with local search heuristics, in future research.

Context: Timber construction is not among the most popular options due to cultural issues in Brazil. Timber housing standards and costs remain uncertain subjects, and this study seeks to investigate these secular gaps. Method: Basic unitary costs for different finishing standards and production types were measured through face-to-face interviews led by a semi-structured questionnaire. A margin of error was used to validate all results. Entrepreneurs from six Brazilian states were randomly interviewed to obtain a representative sample. Results: The sampling exceeded 50% of the sector population and provided significant outcomes. More than 40% of timber housing techniques showed competitive costs in comparison with masonry. There are feasible alternatives of timber housing for the different scenarios analyzed. Conclusions: Timber houses are economically viable in Brazil, even compared to traditional examples built via masonry. Attractive costs for all social classes symbolize a strong factor in conquering housing markets.

Wood is a material that has been used by humankind for a long time. However, wood researchers and industry have always been concerned about the issues during wood drying and the permeability problems of certain species. In this sense, microwave technology has been applied for wood drying and improving permeably. This paper investigates the microwave drying of two Portuguese wood species, Pinus pinaster sap and heartwood and Eucalyptus globulus heartwood using small clear specimens. The samples were grouped into six during each microwave treatment run according to their similarity of initial moisture content. Once the drying was completed, control and microwave -treated samples were impregnated with desalinated water to analyze their improvement in water absorption, and the compression strength parallel to the grain was analyzed. The results showed that each wood species behaves differently under microwave drying and initial moisture content. The impregnation results demonstrated that pine and eucalyptus microwave -treated heartwood samples improved their capability to absorb water. Finally, only the microwave -treated specimens of eucalyptus heartwood presented a decrease in the values of compression strength parallel to the grain compared to the control group. Therefore, MW treatment presents possibilities for further applications for the wood industry with supporting results.

Wood industries use thermal and thermomechanical treatments as ecological approaches to increase the durability of wood products, avoiding the need for chemical additives. In this regard, the aim of this study was to compare the physical and mechanical properties of plywood made from veneers treated at different temperatures using thermal and thermomechanical processes, with untreated panels serving as a control. The treatment process involved Pinus taeda veneers submitted to treatment in a hot press at 1.0 MPa in a laboratory oven at temperatures of 160 °C, 180 °C, and 200 °C for 30 min. For bonding the veneers, a vegetable-based polyurethane resin derived from castor oil with a grammage of 395 g/m2 was used, applying pressing conditions at 90 °C, 0.6 MPa, and 10 min. Our results indicate that temperature significantly influences plywood properties, playing a key role in the choice of equipment for the treatment process. Regardless of the method employed, the treatment resulted in an improvement in the hydrophobicity of the veneers due to the decrease in hemicellulose content. Notably, the reduction in strength and stiffness caused by the loss of cell wall polymers was not statistically significant. The treatment was successful in softening the wood material, reducing roughness, and increasing wettability. Despite a minimum of 20% reduction in glue line tension, the samples still surpassed the 1 MPa mark, showing satisfactory results. This demonstrates the feasibility of adjusting treatment variables to ensure the proper use of this adhesive.

The most widespread wood species in the Portuguese forest and the most widely utilized are maritime pine (Pinus pinaster) and eucalyptus (Eucalyptus globulus Labill). In the case of eucalyptus, except for the pulping sector, it might have limited usage due to drying issues and low permeability. Microwave (MW) treatment is a technology that has been used to improve wood species’ permeability. Therefore, the present paper aimed to evaluate the MW treatment of both Portuguese wood species and to investigate the effects of different MW treatments on wood’s density, water uptake capability, modulus of rupture (MOR), and modulus of elasticity (MOE). Using small clear wood specimens, two MW powers were used, 700 and 1200 W, and the samples were submitted to successive MW cycles of 2 min till they reached the required dryness. The results showed that each wood species had a different behavior during the MW drying in terms of drying rate, supply, and consumption of energy. In general, with the increase in MW power, the densities of both species decreased and the water uptake increased, as a possible indicator that a certain level of microstructural damage might have occurred. Regarding the mechanical properties of MW-treated maritime pine and eucalyptus wood specimens, under the harshest conditions (MW power of 1200 W), MOR and MOE were reduced compared with the wood sample without MW treatment.

This study aimed to compare the mechanical performance of two truss typologies, the modified Fan and Howe trusses, using five different wood species: Cambará-rosa, Cupiúba, Angelim-pedra, Garapa, and Jatobá. The spans considered were 6, 9, 12, and 15 m, and the optimization algorithm used was a swarm intelligence algorithm to minimize the structure weight. The study found that wood is a sustainable and viable option for truss constructions, with different wood species having distinct mechanical properties that must be considered when designing the structure. The Howe truss typology presented lower results for the objective function in comparison with the modified Fan truss. The distribution of normal forces in the truss correlated with the characteristic strength in compression and tensile of the species. The Howe truss typology presented a larger amplitude in relation to the modified Fan truss typology in most of the conditions adopted for the Ultimate Limit State constraints. Constraints associated with deflection in the immediate condition were observed to limit the optimization process. The study used the matrix analysis method to evaluate internal efforts and nodal displacements in the trusses. In summary, this study demonstrates the importance of considering all constraints when dimensioning timber structures and the benefits of using different wood species for sustainable construction.

The development of new materials for the construction sector is a global trend, and products that use by-products in their composition and have also incorporated technology are commercially competitive. Microparticles have large surface areas and can modify the microstructure of materials, positively affecting their physical and mechanical properties. In this context, this study aims to investigate the effect of incorporating aluminium oxide (Al2O3) microparticles on the physical and mechanical properties of oriented strand boards (OSBs) made from reforested residual balsa and castor oil polyurethane resin and to evaluate their durability performance under accelerated aging conditions. The OSBs were produced on a laboratory scale with a density of 650 kg/m3, strand-type particles measuring 90 × 25 × 1 mm3, using castor oil-based polyurethane resin (13%) and Al2O3 microparticle content ranging from 1% to 3% of the resin mass. The physical and mechanical properties of the OSBs were determined following the EN-300:2002 recommendations. The results obtained indicated that the OSBs with 2% Al2O3 presented thickness swelling significantly lower (at the 5% significance level) after being subjected to accelerated aging and internal bonding of the particles higher than the values obtained for the references, evidencing the positive effect of including Al2O3 microparticles in balsa OSBs.

Faz-se necessário, para realizar a verificação de estruturas de concreto em situação de incêndio, conhecer o Tempo Requerido de Resistência ao Fogo (TRRF) dos elementos estruturais. Tanto a ABNT NBR 14432 (2001) quanto a ABNT NBR 15200 (2012) permitem a determinação deste pelo Método Tabular (MT) ou pelo Método do Tempo Equivalente (MTE). Apesar de ambos serem aceitos, comumente encontrarmos no meio técnico e científico, discussões e aplicações do MT, sendo este o que conduz com frequência aos maiores valores de TRRFs. A aplicação de métodos que conduzam a TRRFs menores se justifica por conduzir a estruturas mais econômicas, tendo em vista que os métodos de verificação de estruturas em condição de incêndio se pautam nestes, para definir as dimensões mínimas dos elementos estruturais. Sendo assim, a presente pesquisa objetivou avaliar a influência da aplicação dos resultados dos dois métodos de determinação de TRRF na verificação de um edifício residencial multifamiliar de paredes de concreto. Inicialmente, foram calculados os TRRFs pelos dois métodos e, posteriormente, realizada a verificação da edificação segundo as especificações da ABNT NBR 15200 (2012). A adoção do MTE garantiu uma redução de 12,5% de consumo de concreto, evidenciando a importância da aplicação do mesmo.

Ainda que o Brasil não sofra com catástrofes naturais e sejam incomuns episódios de terrorismo às edificações, a crescente indústria da construção civil demanda práticas cada vez mais audaciosas que divergem do caminho da segurança e da integridade estrutural. Este fato tem gerado cada vez mais preocupação no meio técnico, uma vez que existem profissionais, por desconhecimento do colapso progressivo, negligencie a sua possibilidade e não anteveja os possíveis cenários de dano. Não obstante, a normas no cenário nacional carecem de explicações e de práticas de prevenção a este fenômeno. Isto posto, o presente trabalho tem função de analisar os métodos de aplicação genérica, podendo concluir qual o melhor método a ser utilizado. Um edifício didático foi modelado com a intenção de aplicar três diferentes métodos, chegando-se a conclusão que a metodologia adotada pela norma UFC 04-023-03 de 2009, além de resistir às solicitações típicas do fenômeno de colapso considerado, apresentou acréscimo de material e financeiro razoáveis, plausível de ser empregado na realidade em que vivemos.

O avanço da tecnologia no campo da construção civil vem resultando em estruturas de concreto armado de diferentes soluções e cada vez mais esbeltas, requerendo análises mais refinadas dos que os métodos analíticos previstos em normas técnicas. Essa pesquisa objetivou analisar a precisão de resultados obtidos por meio de aplicação do Método dos Elementos Finitos na simulação numérica de vigas de concreto armado. Investigou-se a influência da escolha de modelos constitutivos e ajustes de parâmetros nos resultados das simulações assim como avaliou-se a precisão de algumas equações analíticas normativas com relação à força última da viga eleita. Para tanto, foi utilizado o software comercial ATENA e as simulações foram validadas com base em resultados obtidos em ensaios de vigas de concreto armado à flexão. Foram testados modelos constitutivos disponíveis no software e ajustes realizados de acordo com critérios previstos na literatura. Dos resultados das simulações numéricas, observou-se uma boa concordância com os valores experimentais e maior precisão quando comparado com os dimensionamentos das normas técnicas. Verificou-se também que a precisão da simulação depende diretamente da definição dos modelos e ajustes adotados na modelagem.

The essences from sylviculture have been usually used for pulp and paper and charcoal industries. For this, the offer of higher value-added examples as structural parts for civil construction is essential. Anyway, this utilization needs to be secured by criteria prescribed by standard documents such as ABNT NBR 7190 (1997) used in this study. Hence, the present paper evaluated the Corymbia citriodora wood to promote its effective use in buildings from the analysis of fourteen mechanical properties and two physical properties. To check the variation of the properties with the moisture content, two conditions were adopted: the initial at 30% and the standard point at 12%, according to prescriptions of this cited Brazilian standard. In total, 2189 repeats were carried out. Seven properties showed visible improvements and influences and in resistance with the observed moisture reduction: perpendicular and parallel compression values and static bending in the modulus of rupture, parallel tensile in the modulus of elasticity, and those strength properties of shear stress, tangential cleavage and toughness. These efficient mechanical resistances evinced that Corymbia citriodora wood could be applied for civil construction, following the trends pointed out by literature.

Aiming to provide greater visibility for the wood species Acrocarpus fraxinifolius, the present study sought to analyze the influence of heat treatment on an industrial scale applied to wood species, also popularly known as Indian cedar. The heat treatment was carried out in an autoclave, with temperature and pressure control, and with saturated steam injection, for temperatures 155 ºC, 165 ºC, 175 ºC, and 185 ºC. Physical, chemical, and mechanical tests were carried out for the analyzed wood. The content of holocellulose and total lignin decreased, while the content of extractives showed a substantial increase. The density increased after the heat treatment, however the treated wood showed cracks, and these cracks influenced the significant loss of the values of the mechanical properties of compression, tension, and flexion. The shear showed strength gain for the temperature of 155 ºC, and the wood treated at 165 ºC was equivalent to untreated wood. The woods submitted to temperatures of 175 ºC and 185 ºC presented strength losses. The heat treatment in question contributes to increase the visibility, use and market value of wood.

ABSTRACT There are several technologies to recover and strengthen timber structures. Two usual alternatives are: the use of steel plates screwed and carbon fiber mats glued with epoxy adhesive. A gap was observed in the literature regarding the study of reinforcement in hardwood timber beams with cross-section loss, commonly found in attacks by biotic or abiotic agents. This study aimed to analyze the flexural stiffness recovery capacity of steel plate screwed to a timber beam with different cross-sectional losses, with a special interest in the effect caused by different bolt arrangements. The results were compared with simulations made using a carbon fiber mat (CF). It was possible to observe that, despite presenting lower efficiency than the CD, the use of steel plate screwed could return the initial stiffness in some models, and the specification of the bolts is relevant in obtaining the results.

A construção civil está em constante busca por desenvolvimento sustentável e inovações, entre as quais está a utilização de pisos intertravados de concreto na pavimentação de vias, estacionamentos e calçadas. Essa área tem passado por transformações, visando à utilização dos resíduos gerados pela construção e demolição (RCD) em sua fabricação. Posto isso, o objetivo desta pesquisa foi avaliar, aos 7 dias e aos 28 dias, o desempenho da resistência à compressão e a absorção de água de pisos intertravados com a implementação do RCD. Foram utilizadas quatro dosagens de RCD (0%, 25%, 50% e 100%) em substituição do agregado miúdo. Após a moldagem, as peças foram submetidas aos ensaios propostos pela NBR 9781 (ABNT, 2013), verificando-se que apenas a dosagem de referência (0% RCD) alcançou 35 MPa de resistência à compressão, conforme as premissas da norma supracitada. Enquanto isso, nos ensaios de absorção de água, apenas as dosagens de 0% e 25% de RCD obtiveram os parâmetros estabelecidos pela norma. Sendo assim, a implementação do RCD em pisos intertravados não alcançou as exigências normativas estabelecidas pela NBR 9781 (ABNT, 2013). Porém, no mercado da pavimentação, existem pisos intertravados comerciais com resistência a partir de 25 MPa para tráfegos leves, o que implica que a dosagem com teor de 25% de RCD apresenta potencial de uso em tais condições.

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.

In line with technological advancements, the construction industry worldwide has sought more efficient building systems in relation to aspects such as increased productivity, reduced material waste and meeting the growing demand. The objective of this research was to use structural joints composed of composite dowels in laminated wood beams as an alternative to connect pieces of wood. Composite materials are composed of a matrix phase and a reinforcement phase and, in civil engineering, are generally applied as reinforcements in concrete structures. This article presents the structural performance of laminated pine timber with composite dowels made of fiber-reinforced polymeric resin (epoxy resin, hardener and glass fiber) (glass-fiber-reinforced polymer, GFRP) with a diameter of 12.5 mm, which was subjected to tensile force in the direction of the connection. For this, an experimental program was carried out that included characterization of the GFRP dowel, characterization of the woods used to make the connection and a tensile test of the connections with the dowels reinforced with fiberglass through a prototype designed specifically for the test. Subsequently, the results were compared with those observed in the literature. In the comparisons, it was possible to conclude that the joints with FRP pins exhibited better performance in terms of shear strength per section than those such as common nails, helical nails (Ardox) and composite structural pins (half-lap, 90°), which were 3.8 mm, 3.4 mm and 6 mm in diameter, respectively. This indicates that this composite material has potential for application in these types of connections. As an original contribution, it proves the feasibility of using this material in dowel joints for wooden structures.