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After the production cycle of latex, Hevea brasiliensistrees becomeresidual living plants for this activity, although their woody trunks are still potentially subject to industrial utilization. Bio-composites derived from rubberwood particles were manufactured using two different configurations as a strategy to examine the potential of this species with respect to mechanical behavior. Homogeneous panels were developed from particles at the saturation condition, and heterogeneous panels were obtained from dry particles conditioned at 12% moisture content. Both examples were heat-pressed and glued with castor oil-based polyurethane resin. Density, short-term water absorption and thickness swelling, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile were evaluated. Panels derived fromrubberwood particles proved to be viable according to the technical standards.

In Brazil, some tile manufacturers have proposed a 10% (5.5°) slope between chords to minimize timber consumption. However, after simulating 21 slopes from 7% (4°) to 27% (15°), it was discovered that the axial strengths are inversely proportional to the slope, creating overly large dimensions for the bars competing for support. The results were obtained using software developed following the guidelines specified in the revised version of the ABNT NBR 7190 (2022) standard. Finally, it was found that the minimum slope until no reinforcement is needed for the string bars is 16% (9°).

The Brazilian standard ABNT NBR 7190 (1997) governs the premises for the wood structure sizing through a table and the simplified method. Thus, this research aims to analyze whether the simplified method shown in the standard matches the resistance values of 72Brazilian species, separated from class C20 to C60. In the end, it was possible to conclude that the value displayed by the standard between theratio of shear and compressionin thedirection parallel to the fibers is half of what actually happens in Brazilian species, showing anurgent review in the standard premises.

Made available in DSpace on 2022-04-28T19:45:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-10-01 HIGHLIGHTS Outcomes with low margins of error are useful for the development of strong forest policies. Native origin timber remains a complex issue and requires efforts to improve clarity. Native timber comprises a significant part of the timber housing sector in Brazil. Exotic timber is used widely throughout the domestic construction industry. In terms of timber housing in Brazil, eucalypt wood is less used than pine. SUMMARY Timber consumption is a complex discussion for the industry, in part because the issue has been marked by doubts about lineage and origin. This paper aimed to identify challenges related to species, origins and wood use in the Brazilian construction sector. Searches on corporate websites and face-to-face interviews were used to identify involvement by species and origin in the domestic production of timber for housing. Relevant results were obtained for both methods since their margins of error were low. Forty exotic and nine native species were revealed to contribute significantly to the construction sector. ‘Grapia' and ‘Angelim pedra' native woods and eight eucalypt and pine species were shown to be the most popular through both methodologies. Pine timber was found to be in greater demand than that of Eucalyptus species. Despite some lack of clarity relating to the origin of certain species, the sector's status was better than expected. However, it still requires assertive actions to increase the use of legalized wood in order to favour product certification and integration into foreign markets. . Post-Graduation Program in Structures and Civil Construction Federal University of São Carlos, 235km Washington Luis Highway Research Group on Development of Lignocellulosic Products São Paulo State University, 519 Geraldo Alckmin Post-Graduation Program in Agriculture São Paulo State University, 3780 Universitária Avenue Post-Graduation Program in Civil Engineering University of São Paulo, 400 Trabalhador Sãocarlense Post-Graduation Program in Forest Resources University of São Paulo, 11 Pádua Dias Avenue Research Group on Development of Lignocellulosic Products São Paulo State University, 519 Geraldo Alckmin Post-Graduation Program in Agriculture São Paulo State University, 3780 Universitária Avenue

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.

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. RESUMO Neste trabalho avaliou-se numericamente a influência do módulo de elasticidade paralelo às fibras da madeira na estabilidade de arcos treliçados, considerando uma análise não linear geométrica baseada no Método dos Elementos Finitos (MEF). Essa abordagem foi realizada conforme uma formulação posicional do MEF, atribuindo-se os nós da estrutura como variáveis principais do sistema de equações não lineares, cuja resolução foi alcançada pelo método de Newton-Raphson. Ao todo, sete modelos de arco foram avaliados adotando-se madeiras coníferas e folhosas, com propriedades definidas segundo as classes de resistência da norma brasileira ABNT NBR 7190. Subrotinas foram desenvolvidas em linguagem MATLAB para resolução do sistema de equações não lineares e processamento da análise, incluindo a representação gráfica dos resultados e configurações do arco treliçado. Valores de esforços internos e deslocamentos foram determinados, assim como as forças de instabilidade dos arcos treliçados. Verificou-se que a força de instabilidade do arco constituído pela madeira folhosa mais rígida (D60) foi aproximadamente igual a 700% da força de instabilidade referente à classe conífera C20, e equivalente a 257,8% da força associada à classe folhosa D20. Concluiu-se que o módulo de elasticidade apresentou influência significativa no comportamento não linear geométrico do arco treliçado de madeira. Além disso, a análise não linear geométrica possibilitou o cálculo de parâmetros mais precisos e a verificação da estabilidade do sistema estrutural.

Made available in DSpace on 2022-04-28T19:44:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 This study aimed to evaluate the influence of commercial thermal treatment on Eucalyptus grandis considering its physical, chemical, and mechanical properties. The wood samples were heat-treated in an autoclave with saturated steam and pressure application at four different temperatures: 155, 165, 175, and 185 °C. The physical, chemical, and mechanical properties were altered due to the heat treatment. The extractives content varied between 6.06% and 28.75%; lignin between 28.93% and 37.96%; holocellulose between 65.01% and 38.12%. The mechanical properties reduced significantly with the increase of the heat treatment temperature. Through the set of data obtained, it was possible to generate significant and high precision regression models capable of estimating such properties for heat treatment temperatures not studied experimentally, enabling the determination of the most suitable temperature of heat treatment to achieve a certain property value of the treated wood. Universidade Estadual Paulista Júlio de Mesquita Filho Programa de Pós-Graduação em Engenharia Mecânica Universidade Estadual Paulista Júlio de Mesquita Filho Departamento de Engenharia Universidade Federal do Sul e Suldeste do Pará Departamento de Engenharia Civil Universidade Federal de São Carlos Departamento de Engenharia civil Universidade Estadual Paulista Júlio de Mesquita Filho Programa de Pós-Graduação em Engenharia Mecânica Universidade Estadual Paulista Júlio de Mesquita Filho Departamento de Engenharia

Plywood is a structural composite mainly applied in construction. For this purpose, some sort of preservative treatment is recommended to increase its durability. One option of the available treatments is heat treatment, which promotes the modification of the wood properties. This treatment is carried out on the final product (plywood), because it can reduce strength if applied to the veneers. However, no study has proven such a reduction. Therefore, the aim of this work was to evaluate three different temperatures (160 °C, 180 °C and 200 °C) of the heat treatment on the veneer surface and on the physical properties (specific gravity, moisture content and swelling in thickness) and mechanical properties (MOE and MOR in static bending) of Pinus taeda plywood. A reduction was observed in the roughness of the veneer’s surfaces and the total extractives content changed, with a minimum value reached in the 160 °C treatment. The plywood specific gravity initially increased with the heat treatment and did not change at higher temperatures, moisture content reduced, and thickness swelling was not affected. There was no change in the mechanical properties of the plywood, evidencing that the veneer heat treatment does not prejudice mechanically the final product.

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.

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. RESUMO Quando a madeira é exposta ao ar livre, uma combinação de fatores químicos e mecânicos e a radiação solar contribuem para o que se denomina intemperismo, sendo o principal agente de degradação nesse ambiente. Este trabalho tem como objetivo investigar o efeito do intemperismo artificial nas propriedades mecânicas e físicas de Eucalyptus sp. e de Cupiúba (Goupia glabra) simulando efeitos naturais do intemperismo. As amostras foram envelhecidas em câmara de radiação UV com controle de umidade e temperatura por 100, 200, 300 e 400 horas, considerando os ciclos de envelhecimento de acordo com ASTM G154 (2006). As propriedades da madeira investigadas foram valor convencional de resistência à flexão estática (fM), módulo de elasticidade à flexão estática (EM), resistência à compressão paralela à fibra (fc0) e dureza Janka (fH) de acordo com a ABNT NBT 7190 (1997). Os efeitos do intemperismo artificial nas propriedades da madeira foram avaliados por análise estatística com nível de significância de 5%. A maioria das propriedades da madeira investigadas não apresentou alterações significativas com o envelhecimento realizado, porém, observou-se diminuição dos valores absolutos das propriedades da madeira durante o processo de envelhecimento. Apenas o fH da madeira de Cupiúba envelhecida por 100 e 200 horas apresentou perda significativa de desempenho no nível de significância considerado, o que pode estar relacionado a alterações na superfície da madeira devido à exposição ao intemperismo.

Made available in DSpace on 2022-04-28T19:45:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The Brazilian standard ABNT 7190 (1997) establishes the strength classes C20, C30, C40 and C60 for the proper framework of the different wood types in the group of hardwoods. Associated with the strength class, which is based on the compressive strength characteristic value parallel to the fibers (fc0,k), the standard stipulates the respective values representing the stiffness (Ec0), with 19500 MPa being the reference value for the class C40, essential variables in structural design. For being the C40 class is the one with the greatest amplitude (20 MPa), it is possible that the value 19500 MPa is not the best representation of stiffness. This work aimed to verify the representativeness the stiffness value established by the Brazilian standard for C40 wood. The result obtained from the average confidence interval indicates the value of 14110 MPa as being the most representative, which may imply structures that are supposedly more rigid than they really are. University of São Paulo Department of Structural Engineering, São Paulo Federal University of Southern and Southeastern Pará Technology Faculty Santana Do, Pará Federal University of São Carlos Department of Civil Engineering, São Paulo Federal Institute of Rondonia Department of Agronomical Engineering, Rondonia São Paulo State University Department of Civil Engineering, São Paulo Federal Institute of Santa Catarina Department of Civil Engineering, Santa Catarina São Paulo State University Department of Civil Engineering, São Paulo

Made available in DSpace on 2021-06-25T10:32:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 This research intends to evaluate the relation, aided by the Brazilian Standard 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. Federal University of Southern and Southeastern Pará (UNIFESSPA) Araguaia Engineering Institute Federal University of São João del-Rei (UFSJ) Department of Mechanical Engineering Sao Paulo State University (UNESP) College of Industrial Timber Engineering Federal University of Sao Carlos Department of Civil Engineering (DECiv) University of São Paulo (USP) Department of Structural Engineering São Carlos School of Engineering of São Carlos Sao Paulo State University (UNESP) College of Industrial Timber Engineering

Made available in DSpace on 2021-06-25T10:27:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 This research aims to investigate, with the aid of the Brazilian standard NBR 7190, analysis of variance (ANOVA—5% significance) and the regrouping bootstrap technique, the influence of the provenance regions Bonfim, Mucajaí and Claudia on the physical and mechanical properties (twenty properties and 720 determinations) of Angelim-pedra (Hymenolobium petraeum Ducke.) and to assess the possibility of estimating, via regression models (152 in all), the physical and mechanical properties investigated as a function of apparent density (ρ12) and compressive strength parallel to the grain (fc0). The results indicated equivalence in most of the physical and mechanical properties, evidencing the small influence of the tree harvest regions. From the regression models, some were considered significant by ANOVA (at the 5% level of significance), which implies that variations in ρ12 and fc0 explain variations in the values of the other estimated properties; however, the low precision indicates that it is not feasible to estimate the variables just based on the ρ12 or fc0. Department of Civil Engineering Federal University of São Carlos Araguaia Engineering Institute Federal University of Southern and Southeastern Pará Department of Mechanical Engineering Federal University of São João del-Rei Department of Production Engineering Federal University of São Carlos College of Industrial Timber Engineering São Paulo State University (UNESP) Department of Civil Engineering São Paulo State University (UNESP) Department of Structural Engineering University of São Paulo College of Industrial Timber Engineering São Paulo State University (UNESP) Department of Civil Engineering São Paulo State University (UNESP)

Made available in DSpace on 2021-06-25T15:04:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) This research aimed to characterize the wood species Goiabao (Planchonella pachycarpa), following the precepts set forth in the Brazilian standard ABNT NBR 7190, as well as to evaluate the possibility of estimating physical and mechanical properties, using the analysis of variance (ANOVA) as a function of apparent density, and also to estimate the stiffness properties as a function of the respective strength property. The physical and mechanical properties were considered adequate for the use of this wood for structural purposes, being classified in class C40. According to the results of the regression models, it is possible to estimate the tensile strength parallel to the fibers as a function of the apparent density. It was also possible to estimate the longitudinal elastic modulus in the compression parallel to the fibers as a function of the compressive strength parallel to the fibers. Fed Univ Southern & SouthEastern Para, Technol Fac, Santana Do Araguaia, Para, Brazil Univ Fed Sao Carlos, Dept Civil Engn, Sao Carlos, SP, Brazil Fed Univ Rondonia, Dept Civil Engn, Porto Velho, Rondonia, Brazil Sao Paulo State Univ, Dept Civil Engn, Ilha Solteira, SP, Brazil Univ Fed Sao Carlos, Dept Prod Engn, Sorocaba, SP, Brazil Mato Grosso State Univ, Dept Civil Engn, Sinop, Mato Grosso, Brazil Univ Sao Paulo, Dept Struct Engn, Sao Carlos, SP, Brazil Sao Paulo State Univ, Dept Civil Engn, Ilha Solteira, SP, Brazil

Made available in DSpace on 2020-12-10T20:04:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01 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 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 (R-2 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. Univ Fed Sao Carlos, Dept Civil Engn, Sao Carlos, SP, Brazil Fed Univ Southern & Southeastern Para, Araguaia Engn Inst, Santana Do Araguaia, Para, Brazil State Univ Sao Paulo, Ctr Enviromental Studies, Dept Stat Appl Math & Computat, Rio Claro, SP, Brazil Univ Coimbra, Dept Civil Engn, Coimbra, Portugal Fed Univ Sao Joao del Rey, Dept Mech Engn, Sao Joao Del Rei, MG, Brazil Univ Sao Paulo, Dept Struct Engn, Sao Carlos, SP, Brazil State Univ Sao Paulo, Ctr Enviromental Studies, Dept Stat Appl Math & Computat, Rio Claro, SP, Brazil

Made available in DSpace on 2021-06-25T12:24:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The present study deals with a production of pine particleboards using the sugarcane bagasse content and using castor-oil based bicomponent polyurethane resin and urea-formaldehyde resin. The influence of incorporation of sugarcane bagasse on the physical and mechanical properties of the composites was evaluated. The particleboards were produced according Brazilian standard ABNT NBR 14810, but performance requirements have been analyzed using Brazilian and international standards, as well. Treatment 2, using PU resin, were considered the best treatment using pine residue and sugarcane bagasse, presenting physical properties values 60% lower and mechanical properties 65% higher on average when compared with panel without sugarcane bagasse, indicating the good performance of sugarcane incorporation and the possibility of its use on commercial purpose for thermal and acoustic insulation. The addition of sugarcane bagasse improved physical and mechanical properties of particleboards when compared to panels manufactured from pine wood particles only. Statistical analysis indicated that moisture content and bagasse content were significant, enhancing properties when compared with reference treatments. Alta Paulista Fac, Dept Civil Engn, Tupa, SP, Brazil Sao Paulo State Univ, Dept Civil Engn, Ilha Solteira, SP, Brazil Fed Univ Southern & Southeastern Para, Technol Coll, Santana Do Araguaia, Para, Brazil Univ Fed Minas Gerais, Dept Civil Engn, Belo Horizonte, MG, Brazil Fed Univ Rondonia, Dept Civil Engn, Porto Velho, Rondonia, Brazil Univ Fed Sao Carlos, Dept Civil Engn, Sao Carlos, SP, Brazil Univ Sao Paulo, Sao Carlos, SP, Brazil Sao Paulo State Univ, Dept Civil Engn, Ilha Solteira, SP, Brazil

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.

The characteristic value of compressive strength parallel to the grain is used to design structural members in bridges, houses and buildings. Such value is obtained based on experimental tests. The Brazilian standard proposes equations to estimate the strengths by means of probabilistic equations that allow obtaining the characteristic values of different mechanical strengths, such as the compressive ( $$f_{c0,k}$$ ), tensile ( $$f_{t0,k}$$ ) and shear ( $$f_{v0,k}$$ ) properties obtained from a set of experimental results. Considering the results for these strengths in parallel direction to grain of 30 hardwoods, with a total of 1080 experimental determinations, the precision of the relations proposed by this standard was duly evaluated from probability distribution models. The Normal, LogNormal, Weibull and Exponential functions were used in order to determine the best adhesion model. Once the values and respective models had been determined for each species, a multivariate linear regression model, based on analysis of variance (ANOVA) and dependent on the mean value ( $${\bar{x}}$$ ), coefficient of variation ( $$CV\%$$ ) and lower (LO) and higher (HI) strength values, was adopted to estimate the $$f_{c0,k}$$ , $$f_{t0,k}$$ and $$f_{v0,k}$$ adjusted with the most significant terms, in order to infer the quality of the estimator and, consequently, the reliability of such mechanical properties. Finally, the multivariate model proposed here was compared to the empirical proposition of the Brazilian standard, to evaluate the reliability of the model and its adequacy in the estimation of the characteristic strengths values to distinguish the mechanical properties of 30 tropical hardwoods.

This paper presents a survey of the state of the art of microwave (MW) treatment of wood, informed by both past and recent research papers. It begins by introducing the main concepts regarding MW technology and its advantages, presenting a holistic perspective of this technology, and identifying 57 research papers published over the last 25 years. Next, an extensive literature review of the most significant experimental research papers is provided, divided into two MW heating treatment uses: wood drying and permeability improvement. For each study, the wood species, MW parameters, main objectives, and overall conclusions are provided. In this context, an explanation is given on how parameters such as MW power, frequency, intensity, and exposure time, as well as initial moisture content, influence the degree of wood modification. Next, a global overview of the most used wood species, genera, and dimensions is revealed. The paper concludes by indicating the potential fields of future research studies concerning the uses and applications of MW treatment technology.

AVALIACAO DA QUALIDADE ENERGETICA DE UM PROTOTIPO DE FOGAO A LENHA PORTATIL PARA NOVE ESPECIES DE EUCALIPTO Os fogoes tradicionais sao energeticamente ineficientes e exigem alta quantidade de lenha. O objetivo desta pesquisa consiste na construcao de um fogao a lenha portatil e eficiente, baseado na tecnologia rocket stove. Esses fogoes sao projetados para um menor consumo de lenha e uma menor emissao de gases (CO2, CO e SO2). O prototipo foi construido com materiais metalicos reciclaveis e vidro moido para isolamento termico da câmera de combustao. Nove especies de Eucalyptus foram utilizadas como combustivel. A avaliacao da qualidade energetica do fogao ocorreu mediante a determinacao da eficiencia energetica e consumo de combustivel, bem como por estimativas da potencia calorifica e quantidade de gases liberados na combustao (CO2, CO e SO2). A eficiencia energetica media alcancou a faixa de 6,8% a 10,4%, com consumo de combustivel em torno de 0,1 kg para cada 20 minutos de funcionamento. A potencia situou-se entre 94,1 e 326,0 W e os teores de gases foram 0,2 Nm3/kg de CO2, 0,02 Nm3/kg de CO e 10-5 Nm3/kg para SO2. As medidas de eficiencia do prototipo desenvolvido superaram medidas similares de fogoes a lenha metalicos residenciais da mesma cidade de Irati, os quais se situam entre 2,9 e 4,6%, tendo o fogao melhorado valor semelhante de outros paises. Portanto, esse prototipo apresentou um resultado bastante promissor, alem de oferecer um baixo custo de producao.Palavras-chave: fogao melhorado; biomassa de floresta plantada; eficiencia; emissao de gases. ABSTRACT: Traditional cook stoves are energetic inefficient and demands high quantity of fuelwood. The aim of this study is to build a portable and efficient cooking stove based on the rocket stove technology that are projected to make better use of the energy released in combustion with lower fuel consumption and gas emission (CO2, CO and SO2) than traditional stoves. Our prototype was built with recyclable metal materials and glass particles for thermal insulation of the combustion chamber. Nine Eucalyptus species were used as fuel. The cook stove evaluation occurred by the determination of thermal energy efficiency and fuel consumption, as well as estimated measurements of the thermal power and released gas amount (CO2, CO e SO2). The average energy efficiency reached the range from 6.8% to 10.4%, with a fuel wood consumption of about 0.1 kg for each 20-minute operation. Thermal power was from 94.1 to 326.0 W, and the gas level was about 0.2 Nm3/kg CO2, 0.02 Nm3/kg CO, and 10-5 Nm3/kg SO2. The thermal efficiency of our prototype exceeded twice than the values of traditional stoves in Irati city that are range from 2.9 to 4.6%, having the improved cook stove similar value of other world stoves. Our prototype presents a promising result in addition to offer a low production cost.Keywords: rocket stove; biomass from planted forest; efficiency; gas emissions.

This research aimed to evaluate the effect of the thermal-treated temperature to improvement of Corymbia citriodora and Pinus taeda wood resistance to the xylophagous termite Nasutitermes corniger, into forced feeding assay. The wood thermally treated was performed at temperatures of 160, 180, 200, 220, 240ºC. For Pinus taeda, the temperature of 260ºC was also used. Three boards of 6 × 16 × 56 cm (thickness × width x length) were used for each temperature. After being thermally treated, the boards were transformed into samples of 2.54 × 2.54 × 0.64 cm (longitudinal × radial × tangential). The experiment was kept in a climatized room (25 ± 2ºC and 65 ± 5% of relative humidity), for 28 days. For Corymbia citriodora, the thermal treatment at 220 and 240ºC improved the resistance to the termite. For Pinus taeda, the resistance improvement occurred at 240 and 260ºC. The temperature of 160ºC caused a decrease in the natural durability of both species. RESUMO Esta pesquisa teve como objetivo avaliar o efeito do tratamento térmico nas madeiras de Corymbia citriodora e de Pinus taeda visando sua melhorar a resistência ao cupim xilofagos Nasutitermes corniger, por meio de ensaios de alimentação forçada. As temperaturas utilizadas nos tratamentos térmico das madeiras foram 160, 180, 200, 220 e 240 ºC. Para o Pinus taeda também foi empregada a temperatura de 260 ºC. Três pranchas de 6 × 16 × 56 cm (espessura × largura × comprimento) foram confeccionadas para avaliar os efeitos de cada temperatura investigada. Depois de tratadas, as pranchas forma transformadas em amostras de dimensões 2,54 × 2,54 × 0,64 centímetros (longitudinal ×radial × tangencial radial). O experimento foi mantidos numa sala climatizada (25 ± 2 ºC e 65 ± 5% de umidade relativa) durante 28 dias. Para a madeira de Corymbia citriodora, o tratamento térmico de 220 e 240 ºC aumentou a resistência ao ataque do cupim. Para as madeiras de Pinus taeda, a melhoria da resistência ocorreu a 240 e 260 ºC. A temperatura de 160 ºC provocou um decréscimo na resistência natural de ambas as espécies.