WOOD RESEARCH Volume 67, Number 5, 2022
Matheus Viana De Souza, Pedro Henrique Da Silva Cazella, Sérgio Augusto Mello Da Silva, Felipe Reis Rodrigues, Marjorie Perosso Herradon, Fabíola Medeiros Da Costa, Márcia Regina De Moura Aouada, Fauze Ahmad Aouada, Herisson Ferreira dos Santos, Edna Moura Pinto, Victor Almeida De Araujo, André Luis Christoforo, and Roberto Vasconcelos Pinheiro

Comparative study of particleboards with Hevea brasiliensis waste from different production and moisture configurations

After the production cycle of latex, Hevea brasiliensis trees become residual 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 from rubberwood particles proved to be viable according to the technical standards.

WOOD RESEARCH Volume 67, Number 4, 2022
Isabella Silva Menezes, IURI FAZOLIN FRAGA, Matheus Henrique Morato De Moraes, ANDRÉ LUIS CHRISTOFORO, Fernando Júnior Resende Mascarenhas, Raquel Schmitt Cavalheiro, Francisco Antonio Rocco Lahr, Eduardo Chahud, Luiz Antônio Melgaço Nunes Branco, and Herisson Ferreira dos Santos

Empirical analysis of roof slope influence on material consumption in timber howe-type trusses

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°).

WOOD RESEARCH Volume 67, Number 2, 2022
Vinicius Borges De Moura Aquino, LARISSA SORIANI ZANINI RIBEIRO SOARES, HELOIZA CANDEIA RUTHES, Felipe Nascimento Arroyo, IURI FAZOLIN FRAGA, ANDRÉ LUIS CHRISTOFORO, Herisson Ferreira dos Santos, Eduardo Chahud, Luiz Antonio Melgaço Nunes Branco, and Francisco Antonio Rocco Lahr

Analysis of moisture content variation on strength and stiffness properties of cedrella odorata wood species

In order to analyze the influence of moisture content variation on Cedrella odorata wood specie on strength and stiffness properties, considering 12% moisture content up to fiber saturation point (FSP). Most of strength and stiffness properties analyzed were significantly influenced by moisture content according statistical analysis. 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 moisture decrease are quite precise, but most of estimations were higher than 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.

WOOD RESEARCH Volume 66, Number 5, 2021
Francisco Antonio Rocco Lahr, Eduardo Chahud, Felipe Nascimento Arroyo, André Luis Christoforo, Edson Fernando Castanheira Rodrigues, João Paulo Boff Almeida, Vinicius Borges De Moura Aquino, and Herisson Ferreira dos Santos

Ratio analysis between compression and shearing of 72 Brazilian wood species

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 72 Brazilian species, separated from class C20 to C60. In the end, it was possible to conclude that the value displayed by the standard between the ratio of shear and compression in the direction parallel to the fibers is half of what actually happens in Brazilian species, showing an urgent review in the standard premises.

WOOD RESEARCH Volume 66, Number 4, 2021
Francisco Antonio Rocco Lahr, Vinicius Borges De Moura Aquino, Felipe Nascimento Arroyo, Herisson Ferreira dos Santos, Sergio Augusto Mello Silva, Anderson Renato Vobornik Wolenski, Carlos Maviael de Carvalho, João Paulo Boff Almeida, and André Luis Christoforo

Influence of stiffness related to the C40 strength class of the hardwood group established by the Brazilian standard in the design of timber structures

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.