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°).
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.
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.
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.