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RESUMO As dimensões de corpos-de-prova para caracterização da madeira são estabelecidas sempre buscando situações em que seja anulada a interferência do atrito nas medidas de deformação. A NBR 7190 (ABNT, 1997) - Anexo B adota corpos-de-prova para o ensaio de compressão paralela às fibras com relação 1:3 entre uma aresta da seção transversal (50 mm) e o comprimento, enquanto a COPANT 464 (COPANT, 1972) e ASTM D 143 (ASTM, 1982) estabelecem a de 1:4. Este trabalho objetivou determinar se as proporções 1:3, 1:4 e 1:5 nos corpos-de-prova, referentes aos comprimentos de 150, 200 e 250 mm, respectivamente, influenciam o Ec0 obtido na compressão paralela às fibras. As análises foram realizadas nas espécies Canelão (Nectandra membranacea), Corymbia citriodora e Angelim (Vatairea sp.). Os valores de Ec0 para as espécies citadas apresentaram-se estatisticamente equivalentes entre si, ao nível de 5% de significância, demonstrando que as variações nos comprimentos dos corpos-de-prova não afetaram esta propriedade.

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.

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.

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).

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 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.

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.

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 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.

Engineered wood products need alternatives of raw materials to their production. The hybrid Eucalyptus urograndis has great potential to supply the demand of this industrial sector. In this context, the present paper aims to analyse the feasibility of using Eucalyptus urograndis in glued laminated timber (glulam) production. To this end, four groups with ten glulam beams each, were produced and tested. An extensive experimental program was performed in order to determine: the stiffness and bending strength of the beams; and the compression strength parallel to grain of the beams. The performance of structural adhesives was verified based on shear tests of glue lines. The experimental mean of stiffness was higher than 14675 MPa and the characteristic value of compression strength parallel to grain achieved a value above 40 MPa. Nevertheless, failure mode of the glulam beams showed that finger-joints reduced bending strength. The glulam beams produced with Eucalyptus urograndis proved to be a feasible alternative due to their mechanical properties. However, this material presents difficulties in finger-joints adhesion.

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.

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.

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.

Abstract The present study aimed to characterize medium density particleboard manufactured with CCB treated particles of Pinus sp. wood specie and alternative mixed vegetal oil-base bicomponent polyurethane resin. For this, three different resin concentrations (10 %, 12 % and 15 %) were used in combination with the presence or absence of the CCB preservative, resulting in six distinct treatments. The particleboards were produced according the Brazilian Standard - NBR and evaluated according European standards - EN. The results met the requirements of NBR and EN. The technical feasibility of making panels with those materials used were proved and the quality of the product according to its performance were verified, indicating the possibility to use alternative bicomponent polyurethane resin from mix vegetal oil. Statistical analysis demonstrated that adhesive and preservative factors and the interaction between them were significant on physical and mechanical properties.

Abstract According to the Brazilian standard for wooden structures, strength and stiffness increase linearly with decreasing moisture; however, as wood is a natural, heterogeneous and anisotropic material, certain strength and stiffness properties may not be affected even by large differences in moisture. Therefore, this work aims to evaluate the reliability of the resistance and rigidity transformation equations as a function of moisture, used to correct the properties when the test was not performed at 12% moisture. Furthermore, it was checked whether the humidity affects the properties of the studied species. Of the 15 properties analyzed, 2 did not show changes when analyzed at the fiber saturation point and at 12% moisture. Additionally, the correction equations of the Brazilian standard showed errors of up to 24% in the estimation of properties at 12% moisture. Thus, the need to correct the Brazilian standard for wooden structures is evident.

This research intends to evaluate the relation, aided by the Brazilian Standard ABNT NBR 7190 and statistical analysis (Kruskal-Wallis ANOVA and bootstrap technique), between physical and mechanical properties of Cambará-Rosa wood harvested from three different regions: Vera, Mucajaí and South Rondonia. In addition, the possibility to estimate (regression models) physical and mechanical properties in function of apparent density was analyzed. Different climate and soil conditions which tree thrives may influence its growth and, consequently, its properties values. The results of ANOVA indicated an elevated equivalence index for all three regions. The bootstrap technique led to similar results for Vera and Mucajai regions, and for South Rondonia region, equivalence index equals to 89 %. The ANOVA results to estimate physical and mechanical properties in function of apparent density indicated that it is not possible to perform such estimates for Cambará-Rosa wood species.

O uso da madeira, principalmente se tratando da madeira laminada colada, agrega versatilidade às construções, pois peças mais longas e com seções mais robustas podem ser fabricadas, apresentando boa proteção contra incêndios, além de se tratar de fonte sustentável de matéria-prima. Dentre as estruturas que podem ser construídas a partir da madeira, encontram-se as torres de escalada, comumente encontradas em países europeus. Com o auxílio das normas Eurocode 5 (2004) e ABNT NBR 7190 (1997), o presente trabalho propõe um design e a posterior verificação estrutural de uma torre de escalada constituída de elementos de madeira serrada e colunas em madeira laminada colada, cabendo destacar que as verificações devem respeitar aos estados limites último e de serviço relativos à resistência e à estabilidade, sendo dada ênfase para a verificação de estabilidade neste trabalho, estabelecendo uma comparação geral entre ambos os documentos normativos. Os resultados apontaram para alguns elementos em condição de instabilidade em flexo-compressão, sendo que a norma brasileira se mostrou menos rigorosa quanto a tal verificação.

ABSTRACT In this work, it was numerically evaluated the influence of the modulus of elasticity parallel to the wood grain on the stability of trussed arches considering a nonlinear geometric analysis based on the Finite Element Method (FEM). This approach was carried out according to a positional formulation of the FEM, considering the structural nodes as main variables of the nonlinear equations system, whose resolution was obtained using the Newton-Raphson method. Altogether, seven arch models were evaluated, consisting of coniferous and hardwoods, with properties defined according to the strength classes of the Brazilian standard ABNT NBR 7190. The subroutines were written in MATLAB to solve the system of nonlinear equations and perform the analysis, including the graphical representation of the results and configurations of the trussed arch. Internal loads and displacements were obtained, in addition to the instability loads of the trussed arches. It was found that the instability load of the arch made with the stiffest hardwood (D60) was approximately equal to 700% of the instability load of the C20 coniferous class and equivalent to 257.8% of the D20 hardwood class-related load. It was verified that the modulus of elasticity significantly influences the nonlinear geometric behavior of the timber trussed arch. Furthermore, the nonlinear geometric analysis allowed calculating more accurate parameters and the verification of the stability of the structural system.

ABSTRACT The recent interest in constructing high and robust wooden structures has stimulated the investigation of physical and mechanical properties as well as their correlation with other important parameters of the material of tropical species like the Vatairea sp., whose popular name is angelim-amargoso, used especially in roof structures with large spans. The Brazilian Standard for wood constructions recommends using linear models to correct or estimate the strength and/or stiffness of wood correlated with moisture content and also provides the classification of hardwoods according to their characteristic strength. However, because wood is a natural, heterogeneous, and anisotropic material, certain properties may not be affected by significant differences in moisture content. Therefore, in this study, the influence of moisture content on fifteen physical and mechanical properties of Vatairea sp. wood was investigated through its characterization. The tests were carried out on 12 specimens for each property and two groups: with the moisture content of 12% and at the fiber saturation point. The Anderson-Darling test was performed to verify the results’ normality and the analysis of variance (ANOVA) to analyze the influence of moisture content on these properties. In addition, the wood was classified according to the strength classes of the Brazilian Standard, and the strength and stiffness were estimated according to the linear models proposed by the same norm. The estimated results were compared with the experimental ones through the difference calculation and percentual error of the values. It was concluded that most properties were not affected by the moisture content, and the most significant errors obtained in the estimates were for properties that were significantly influenced by the moisture content.

Abstract The objective of this research is to evaluate the possibility of use of tropical hardwood species (Amburana cearensis and Cedrella fissilis) for grilling plank production. Physical, chemical and organoleptic properties were evaluated and compared with properties of a well-used wood specie for grilling plank across Europe and USA, Western Red Cedar (Thuja plicata). For chemical analysis, three techniques were used: hydro distillation, soxhlet and head space. Normality test and analysis of variance (ANOVA) were used for the comparison between Thuja plicata and tropical hardwoods. The results of organoleptic, chemical and statistical analysis demonstrated the possibility of use of Amburana cearensis and Cedrella fissilis on grilling plank production, with no volatile compound present in these species being toxic, low apparent density and Nerolidol presence, chemical compound used as flavoring agent, enabling their use as grilling planks.

This paper aims to evaluate the hypothesis regarding the homogeneity of wood batches, as provided in the Brazilian standard for wooden structures ABNT NBR 7190 through an experimental study simulating the condition of a sawmill where the control of the harvest region, location of the sample in the trunk, edaphoclimatic condition, relief, and vegetation are variables that cannot be controlled. An experimental study was performed on 15 properties (3 physical and 12 mechanical) of Ipe (Tabebuia sp.) wood. Batches from three harvesting regions (Mucajaí [RR-A], Bonfim [RR-B], and Cláudia [MT]) were used to verify the existence of significant differences between the properties of the three areas. The properties were obtained following the test methods established in ABNT NBR 7190-3, with 540 specimens being manufactured and characterized, prior to being submitted to a statistical analysis, where ANOVA was applied with the Anderson–Darling normality test, the homogeneity of variance of multiple comparisons, and the Tukey test. Statistical analysis indicated that the wood harvesting regions showed significant differences in six (40%) and non-significant differences in nine (60%) of the fifteen properties evaluated. Among the properties evaluated, the compressive strength parallel to the grain (fc0) showed significant differences. This property is used to classify the wood strength class according to the Brazilian standard ABNT NBR 7190-1. The batches from the harvesting regions RR-A, RR-B, and MT were classified using the strength classes D60, D50, and D50, respectively. These results directly impact the consideration of the homogeneity of the batches, considering that the sawmills receive samples from different regions. For future research, a numerical method can be applied to consider the influence of the wood harvesting area.

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.

ABSTRACT Wood is an important building material used in roof structures, bridges, viaducts, and pedestrian bridges. In order to improve its use, as well as rehabilitate structural parts deteriorated by weathering, reinforcement of beams and columns with composite material is performed. Given the climate action on structures, it is important to know the influence and behavior of wood and composite material when subjected to weathering. This study aimed to evaluate the influence of the reinforcement of CCB-treated wood with carbon fiber reinforced polymer (CFRP) and subjected to artificial weathering on its tensile strength parallel to the fibers. The results showed a 30% reduction in strength due to weathering and a 25% increase in tensile strength, showing the positive influence of reinforcement even under artificial weathering conditions

ABSTRACT When wood is exposed outdoors, a combination of chemical and mechanical factors and solar radiation contribute to what is described as weathering, being the main degradation agent in this environment. This paper aims to investigate the effect of artificial weathering on mechanical and physical properties of Eucalyptus sp. and Cupiúba (Goupia glabra) woods simulating natural weathering effects. Samples were aged in UV radiation chamber with humidity and temperature control for 100, 200, 300 and 400 hours, considering aging cycles according to ASTM G154 (2006). Wood properties investigated were Conventional value of strength in static bending (fM), Modulus of elasticity in static bending (EM), strength in compression parallel to grain (fc0) and Janka Hardness (fH) according to ABNT NBT 7190 (1997). Effects of artificial weathering on wood properties were evaluated by statistical analysis at 5% significance level. Most of the wood properties investigated did not present significant changes with the aging performed, however, it was noted a decrease in the absolute values of the wood properties absolute values during the aging process. Only fH of Cupiúba wood aged for 100 and 200 hours presented significative performance loss at the significance level considered, which can be related to changes on the wood surface due to weathering exposure.

Background and Purpose: Eucalypt is an important raw material source of several industrial purposes. However, some eucalypt essences are still underutilized, possibly due to the lack of more embracing information about their properties. In this way, Eucalyptus maidenii species has presented a wide potential, and its lumber utilization is somewhat interesting. Nevertheless, a complete determination of its physical and mechanical properties, as carried out in this paper, certainly could encourage its popularization in construction. Materials and Methods: Eucalyptus maidenii evaluation included two physical and fourteen mechanical parameters, regarding standard documents from Brazilian National Standards Organization (ABNT) and American Society of Testing Materials (ASTM). Thus, a simple comparison was established concerning the moisture content of wood samples, which were evaluated through two conditions: 30% as the initial level and a standard at 12%. All results were statistically evaluated by t-test. In sixteen parameters, 310 determinations were carried out. Results: Half of mechanical properties presented significant changes in their resistances with the analysed moisture reduction. Modulus of rupture in static bending and in perpendicular compression, modulus of elasticity in perpendicular compression, strength in tangential cleavage, shear stress, and perpendicular and parallel hardnesses increased their resistances when the moisture content was reduced from 30% to 12%, that is, from green to dried standard stable point. Bulk density was also changed in the evaluated condition, decreasing to a smaller value. Volumetric mass density, modulus of rupture in parallel compression and in parallel and perpendicular tensiles, as well as modulus of elasticity in static bending and in parallel compression and tensile, and tangential toughness did not show any alteration in their values with this studied condition. Conclusions: Lumber for civil construction needs to be suitable for efficient application, with air equilibrium, generally at 12% of moisture content as international normative documents require. As part of this, mechanical and physical properties/parameters were studied to characterize Eucalyptus maidenii wood regarding moisture content. The results obtained indicate the use of this essence from planted forests for structural purposes in construction.

To ensure the safety of wooden structures, estimation of wood strength is based on the characteristic strength values. The Brazilian standard (NBR, in Portuguese Norma Brasileira Regulamentadora) 7190 proposes equations to estimate the strength properties with a simplified procedure, which allows obtaining the characteristic values through relations that correlate different mechanical properties. Using these equations, the values of tensile (ft0,k) and shear (fv0,k) strength can be calculated in a simplified way from the compressive strength (fc0,k) values. In the present work, 36 tropical hardwood species were evaluated for tensile, shear and compressive strength in the direction parallel to the grain, with a total of 1296 experimental measurements, and the precision of the relations defined by the Brazilian standard was assessed using the analysis of variance (ANOVA) method. Two-parameter regression models, based on linear, exponential, logarithmic and geometric functions, were used as an alternative proposal for the estimation of the strength properties. The statistical analysis validated the proposed relations, with the linear (ft0,k) and geometric (fv0,k) regression models being the models of best fit, with the coefficients of determination (R2) equal to 63,02 % and 70,15 %, respectively. In addition, new simplified equations were suggested. The least squares method was used to determine the optimal coefficient (α) for validation of the Brazilian standard equations. The obtained coefficients validated the tensile strength relationship (ft0,k = fc0,k / 0,77), but failed to validate the shear strength relationship (fv0,k = 0,12∙ fc0,k). In the latter case, the obtained values were significantly higher (up to 91 % higher) when compared to those estimated by the Standard

Wood strength values are calculated based on the characteristic value, which corresponds to the 5 % percentile of a given probability distribution model. For a few number of samples (12 samples), the Brazilian standard ABNT NBR (7190) establishes an estimator of the characteristic compressive strength parallel to grain of the wood, which may provide a different result when compared with the characteristic value coming from a suitable probability distribution model. Considering the strength results in the parallel compression to the grain of 45 wood species of the hardwood group, Normal, LogNormal, Weibull and Exponential probability distribution models were used for each specie with the purpose of determining the one with the highest adhesion. Calculated the characteristic values by the best probability model distribution, an analysis of variance (ANOVA) was performed in the estimation of the characteristic value of compressive strength, making it possible to identify the most significant terms of the models as well as the quality of the adjustment obtained on such models. The proposed regression model (R2 adj= 96,56 %) proved to be equivalent to the empirical model of the Brazilian standard. The model proposed here only depends on the mean and the lowest value obtained from the compressive strength in the parallel direction to the grain.

Abstract Wood offers a good combination of high strength and low density, but its complete characterization takes a long time. This study aimed to correlate apparent density, chemical component and porosity parameters with the physical and mechanical properties of the wood as an alternative route to reduce the time spent proposing equations to estimate each mechanical property. Ten tropical wood species were characterized in accordance with Brazilian Standards and chemical components were determined by the Klason method, and the porosity using mercury intrusion. Multivariate regression models were applied to the results of each species to find the relationships. Good results were obtained, such as the coefficient of determination and the analysis of variance, which indicated that the equations for 10 out of the 16 properties are significant. Therefore, the apparent density, chemical component and porosity parameters used reduce the time intervals much lower than the time test stipulated by the standard.

Wood has several advantages as structural material. For this use to be applied in a safe way, it is necessary to know the statistical behavior of the mechanical properties. Some works and normative codes, such as the “Brazilian timber standard” (as well as its review project), accepts a normal distribution model for determining the characteristic value of compressive strength parallel to wood fiber, with the adoption of a coefficient of variation for this property equal to 18 %. This work evaluates the distribution model of compressive strength parallel to the fibers, as well as the coefficient of variation of this property. Tests and statistical treatment were performed in compression parallel to the fibers for 7 species of hardwood commonly found in Brazil. It was observed that the compressive strength of wood actually follows a normal distribution, and the adoption of an average coefficient of variation equal to 18 % is acceptable and in favor of safety.

Forest Red Gum eucalypt provides a versatile wood and is converted into different purposes. However, such wood is somewhat limited in structural ends, which highlights the need to exploit this gap through diffusion of mechanical properties of such timber. Obtained results should assist engineers and architects in decision-making for its best building application. This paper studied two physical and fourteen mechanical properties evaluation of Eucalyptus tereticornis at two different moisture contents, following the prescriptions of Brazilian (ABNT NBR 7190: 1997) and North American (ASTM D-143-14: 2014) standard documents. Thus, 1091 repeats were carried out for all properties. By a moisture reduction from 30% to 12%, the bulk density and eleven strength properties statistically showed changes such as modulus of rupture (static bending, parallel and perpendicular compressions), modulus of elasticity (perpendicular compression and static bending), shear stress, tangential cleavage, and parallel and perpendicular hardnesses. Then, the Eucalyptus tereticornis timber could be better usable if is further applied for structural construction uses.

This aim of this work is to present an analysis of the influence of impregnation against biological demand, realized with saline solution of CCB (Chromated Copper Borate preservative) by vacuum-pressure process, on physical-mechanical properties of tropical wood species Simarouba sp., Cedrelinga catenaeformis and Erisma uncinatum Warm. In theory, such process could increase the number of surface defects in wood pieces and reduce its strength properties. To investigate this influence, the complete species characterization was carried out in two conditions (without treatment and CCB treated wood). Tukey’s multiple comparisons test (5% significance level) was applied. In addition, scanning electron microscopy (SEM) photomicrographs were obtained with the energy dispersive spectroscopy (EDS) to investigate preservative presence at the cellular level. Results permitted to conclude that CCB impregnation process did not affect physical-mechanical properties of the studied species.

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.

Improve quality of timber structures design is an aim that must be systematically sought by engineers in this area. An important topic that can contribute directly to be achieved in this subject is the more consistent knowledge related to structural properties of wood. Know values of longitudinal modulus of elasticity (E) and shear modulus (G) is essential for proper evaluation of plate structures performance, as example. It has been usual to adopt statistical equivalence for E and G values in plans longitudinal-radial and longitudinal-tangential, although experimental confirmation of this hypothesis is required. In this context, the aim of this work is to determine values of ELR, ELT, GLR and GLT, based on static bending tests, to five dicotyledonous species. Results showed statistical equivalence between the elastic properties in both plans, and the relation E = 35G was obtained for the five wood species here considered.

Natural resource exploration is growing, highlighting woods and joinery waste, wood industries and the like. This study presents homogeneous particleboard (PPH) roughness characterization manufactured from treated wood waste. Normative document with values of Brazilian Technical Standard Association ABNT NBR 8404 (1984), was adopted as a reference. The results show that the manufactured PPH showed roughness class N 10, with roughness values (Ra) of less than 12.5 microns.

Wooden housing is one of the most sustainable building alternatives. In many European and North American countries, wooden houses provide the most common, economical, and practical solution for construction. The timber buildings present adequate levels of durability, acoustics, and thermal comforts. Despite their popularity, wood houses do not have a standardized classification to define and organize their main aspects. In literature dealing with timber construction, most authors emphasize structural systems for large spans (bridges, hangars, roofs, etc.). The presence of some classifications of timber construction results in unclear issues, and few studies have covered and regarded wooden buildings as residential construction typologies. Accordingly, this paper proposes a classification that connects the aspects and details of wooden housing materials in relation to the industrialization level and chronological origin. We expect this classification to assist in a better understanding of distinct wooden housing techniques commercially produced worldwide, diffusing their concepts and possibilities as forestry-timber products.

In Brazil, the characterization of solid wood for structural design must be carried out according to the recommendations of the ABNT NBR 7190:1997 standards. Studies about alternatives to improve reliability to test methods are always relevant. Thus, the present study aims to examine the bending modulus of elasticity of samples of three wood species: Canelão (Nectandra membranacea), Corymbia citriodora (Corymbia citriodora) and Angelim (Angelim sp). The results for Canelão and Angelim showed statistical equivalence between the methods at 5% significance level. However, for the Corymbia species, statistical differences of results for bending tests with three and four points were observed. More studies are recommended in order to investigate other wood species, different strength classes and moisture content ranges.

This study aimed at making and testing a portable wood stove, which presented an average efficiency of 12.3%. This percentage was higher than the 2.9 to 4.6%. range found in residential stoves in the city of Irati/PR. The fuel used in the experiment was wood from the Mimosa scabrella tree, with 13% moisture content. The thermal power of the portable stove was 241.3W; the fuel consumption was 0.2 kg for each 20-minute of operation, and the levels of volatiles were 0.1 Nm3 CO2/kg, 0.01 Nm3 CO/kg and 9.610-6 Nm3/kg for SO2. These results show that the wood stove presents very promising results.

Este trabalho objetivou a construção e teste de um fogão a lenha portátil, que apresentou eficiência média de 12,3%, enquanto que para os fogões residenciais utilizados na cidade de Irati/PR, a eficiência energética varia na faixa de 2,9 a 4,6%. Utilizou-se como combustível lenha de madeira Mimosa scabrella, com 13% de teor de umidade. O fogão portátil apresentou potência de 241,3 W; consumo de combustível em torno de 0,2 kg para cada 20 minutos de funcionamento e como teores de voláteis aproximadamente 0,1 Nm3/kg de CO2; 0,01 Nm3/kg de CO e 9,6 10-6 Nm3/kg para SO2, consistindo assim em resultados promissoress.

RESUMO Este trabalho objetivou investigar a influência das regiões de extração (Municípios de Caracaraí e Bonfim, Sul de Roraima; Município de Alta Floresta, Norte de Mato Grosso) da madeira da espécie jatobá (Hymenaea stilbocarpa). Também, foi avaliada a influência do teor de umidade (madeira saturada e a 12%) em 15 propriedades físicas e mecânicas de interesse. Ao todo, foram preparados e ensaiados, segundo as prescrições da Norma Brasileira ABNT NR 7190 (1997), 840 corpos de prova. Os resultados da análise de variância (a 5% de significância) revelaram que a região de extração dos corpos de prova não foi significativa nas propriedades físicas e mecânicas avaliadas, pois foram obtidos valores equivalentes, independentemente da origem, aspecto altamente interessante à medida que nem sempre é possível identificar a região de onde provém a madeira tropical. Essa importância é ainda maior no caso do emprego da madeira como elemento, cujos valores de referência se encontram apontados nos anexos do referido documento normativo. Com relação ao teor de umidade, foi observada diferença significativa em oito das 15 propriedades avaliadas. A condição de 12% de teor de umidade apresentou valores médios superiores à condição saturada nas propriedades de resistência na compressão paralela (37%), resistência na tração paralela (29%) e cisalhamento (36%) na direção paralela às fibras; módulo de resistência na flexão (26%), módulo de elasticidade na compressão paralela (9%) e 200 direções paralelas (35%) e normal (28%) às fibras; e inferior na densidade aparente.

This research aimed to present a numerical methodology of calculation, based on the Finite Element Method and the Least Squares Method, to determine de longitudinal modulus of elasticity in structural round timber beams, considering the irregularities in the geometry of the elements by linear approximation along the finite elements. In addition with the numerical model (1D), together, two others were used, one analytical (1D simplified), which considers a single value of diameter (cylindrical geometry), measured at the midpoint of the elements, and another numerical model (3D), allows more accurately to delineate the geometry of the element, enabling check the difference between them. Therefore, the beams were evaluated according to the static three-point bending test, being tested twenty four elements of Pinus elliottii wood species, with average length of 630 cm, breast height diameter around 21 cm, green wood (satured), tape average of 6% and mean of factor form section of 0,82. The results of the confidence interval between the modulus of elasticity of the 1D numerical model (Eo) and analytical (Edeq) showed statistical equivalence between the methodologies, justified by the small taper of the elements, may be different for others tapers. The use of the longitudinal modulus of elasticity obtained from de numerical 1D model in the 3D simulations of the round timber beams lead to displacement values equivalent to those obtained in the tests, proving the efficiency of 1D numerical model, requiring less computational work.

RESUMOO módulo de elasticidade na compressão paralela às fibras (Ec0) é um dos parâmetros de referência para estimar o desempenho da madeira. O Anexo B da Norma Brasileira ABNT NBR 7190:1997 estabelece, nos ensaios para determinação do Ec0, que seja tomada a medida de deformações em pelo menos duas faces opostas dos corpos de prova. O objetivo deste trabalho foi verificar a influência dessas condições de ensaio nos valores de Ec0. Tal propriedade foi determinada a partir das deformações de duas faces opostas dos corpos de prova e, em seguida, a partir das deformações obtidas nas faces complementares. Foram utilizadas espécies de madeira de forma a abranger todas as classes de resistência assumidas pela citada norma. Os resultados indicam significativa variação de Ec0determinado nos ensaios referidos, evidenciando que tal situação deve ser considerada para futura revisão dos métodos de ensaio para determinação de propriedades da madeira para aplicação estrutural.

Temperature in timber roof trusses structures can reach 60°C and significantly affect wood strength, compromising the structural mechanical performance. This study aimed at quantifying the influence of exposure time to the mentioned temperature in wood strength by monitoring shear parallel to grain (fv0) of Pinus taeda and Pinus elliottii from planted forests. Exposure times at 60°C, in controlled oven, consisted of zero, 168, 456 and 720 hours. ANOVA results indicated that temperature (60°C) influences significantly, in the four exposure times, fv0 for both Pinus wood species. For Pinus taeda, slightly more resinous, strength in shear parallel to grain presented successive reductions, related to reference condition (zero hour) for exposure times 168 and 456 hours; and increase for 456 hours to 720 hours. Different behavior was observed for Pinus elliottii, where fv0 successively showed increases from reference condition for the other temperatures. Even with varied behavior of Pinus wood referring to the influence of exposure times at temperature 60°C, shear strength was significantly affected.

This study aimed to evaluate the feasibility of using and influence of alternative wood species such as Cambará, Paricá, Pinus, and wood from first thinning operations on oriented strand board (OSB) physical and mechanical properties. Besides that, an alternative resin, castor oil-based polyurethane, was used to bond the particles, due to the better environmental performance when compared to other resins commonly used worldwide in OSB production. Physical properties such as the moisture content, thickness swelling, and water absorption, both after 2 and 24 hours of water immersion, and mechanical properties such as the modulus of elasticity and resistance in static bending, in major and minor axes, and internal bonding were investigated. All tests were performed according to European code EN 300:2006. Results showed the influence of wood species on physical and mechanical properties. Panels made with higher density woods such as Cambará presented better physical performance, while those made with lower density woods such as Pinus presented better mechanical properties. Besides that, strand particle geometry was also influenced on all physical and mechanical properties investigated. Therefore, the feasibility of using alternative species and wood from first thinning and with castor oil-based polyurethane resin in OSB production was verified.

A multilayer particleboard panels, consisted of sugarcane bagasse reinforced composite as core material and hybrid composites made with Pinus taeda particles and Malva fibres as facing materials, were designed and evaluated in this work. Tukey test was used to identify the effect of the facing material, considering different combinations of Pinus taeda particles and Malva fibres, on the bulk density, thickness swelling, flexural strength, flexural stiffness and X-ray densitometry. A spray-up process was used to spread castor oil based polyurethane resin upon the dispersive phases followed by a hot compaction at 100oC. The particleboards were classified as medium density panels in accordance to the Brazilian, American and Canadian Standards. All treatments reached the minimum strength except for elastic modulus. Tukey test demonstrated the flexural strength and modulus responses for all treatments were statistically similar. Hybrid particleboard consisted of 75% of Pinus taeda wood and 25% of Malva fibres revealed a promising sustainable material for furniture industries, combining strength, low-cost and lower thickness swelling values.

Os produtos manufaturados em madeira são fundamentais para a sociedade moderna, visto que os mesmos são fabricados a partir de matéria-prima renovável e reciclável, caracterizando um insumo sustentável. O objetivo deste trabalho consistiu em elucidar a importância da madeira de florestas plantadas na manufatura de produtos florestais com maior valor agregado, abordando os contextos florestais e madeireiros de tópicos relacionados à educação, recursos, produtos, indústrias, incentivos estatais, políticas públicas e mercado. Verificou-se que o Brasil, diferente da Europa, não estimula favoravelmente esse importante setor industrial, que ainda assim apresenta potencial de crescimento em função da diversidade de produtos à base de madeira. Desse modo, a madeira poderá alcançar um lugar de destaque na economia do País, se estratégias e incentivos forem definidos por meio de normas e políticas públicas.

The focus of this research was to study the utilization of residues from bamboo (Dendrocalamus giganteus) lamination in the manufacturing of panels for structural purposes. Bamboo particleboards were produced under three conditions: pure boards, reinforced with bamboo laminas, and with treated particles. Castor oil-based polyurethane was the resin binder, in view of using lower toxicity materials. The mechanical tests were performed according to Brazilian Standard (NBR) 14810-3 (2006) and European Standard (EN) 310 (2000). The results were superior to those recommended by these and other standards for internal adhesion resistance, modulus of rupture, and elasticity in static bending, as well as to the results of other studies. Starch treatment was an unnecessary stage. According to the conditions of this process, the studied panels showed a good potential for construction use. Moreover, the bamboo particleboards are an economically viable, environmentally friendly, and sustainable alternative for the use of waste generated during the processing of Dendrocalamus giganteus bamboo species, allied with castor oil-based polyurethane resin. The reinforced particleboard and its production process are being licensed as an Innovation Patent in Brazil, (BR 1020130133919-1-2013).

The Glued Laminated Wood has a large range of applications. In Brazil, its employment as cross-piece poles for overhead electrical power has attracted the attention of companies in the industry, motivated by the potential use of this material. Among the factors that influence the mechanical performance of Glulam solutions stand out efficiency and affinity of the adhesives to the species of wood used, the type of treatment and moisture content of wood veneer, motivating the development of new research on this topic. This research aimed to investigate, by Design of Experiments (DOE), the influence of wood (pinus, teca, eucalipto), adhesive (Purbond; Cascophen) and treatment (CCA, CCB, CCBS ) in the variable responses shear strength and delamination, consisting in the same combination factors evaluated in ANEEL/EESC-PD220-07 project: Head Crosshead Glulam Series. The results of the statistical analysis showed that the species factor expressed significant effect for both response variables evaluated, did not occur with adhesive and treatment factors. Moisture content was significant in the wood evaluated when analyzed the shear strength, and the teca wood showed the highest shear strength and also relating to the delamination.

The objective of this work was to evaluate the effect of the addition of bamboo laminas of the species Dendrocalamus giganteus to three-layer medium density particleboard (MDP). These laminas were glued onto both the top and the bottom of each panel. With the manufactured panels laminated with bamboo, mechanical tests based on the Brazilian Standard ABNT NBR 14810 were carried out to determine the modulus of rupture (MOR) in static bending and the tensile strength parallel-to-surface. These mechanical tests were realized in particleboards of eucalyptus and in reinforced particleboard, both produced in the laboratory. The modulus of rupture and tensile strength parallel-to-surface of the laminated MDP had values close to those that have been reported. The reinforcements increased the values of these studied properties. Nevertheless, this fact indicated the possibility to produce a stronger MDP using bamboo lamina as surface layers. These results show the possibility of using coated-bamboo MDP for utilization in large spans, for example, in flooring for mezzanines with finish on both sides, and for robust furniture as bookshelves, beds, tables, etc.