Density as Estimator of Strength in Compression Parallel to the Grain in Wood

Abstract

Wood is a renewable material, presenting wide use in building construction. For its better employability, it is necessary to perform physical and mechanical characterization of the several species available for application. In this respect, Brazilian Code ABNT NBR 7190:1997-Timber Structures Design, in its Annex B, prescribes the proper tests and adds some relations between properties and strength classes for coniferous and dicotyledonous. The strength classes are function of characteristics values of strength in compression parallel to grain (f c0). However, density is a more easy-determination property and the cited Code presents the mean value of density for each strength class. Therefore, this research aimed to evaluate the possibility of inferring f c0 based on density obtained on tests of three Brazilian tropical wood species: Canafístula (Cassia ferruginea); Angelim araroba (Vataireopsis araroba) e Castelo (Gossypiospermum sp.). Statistical procedures shown it is possible to conclude that, in some cases, density is not a good estimator of f c0 .

Density as Estimator of Dimensional Stability Quantities of Brazilian Tropical Woods

“…The strength characteristic value could be non-directly proportional to the density due to variations of anatomical parameters between species. This explains the higher density values found for the C30 class related to the C40 class, as researched by Almeida et al (2016). Table 3 presents the best fit obtained by the investigation of the relations of different groups (showing the best fit with ρ12 as an estimator), determination coefficient (R 2 ), and P-values of the models, which were all considered significant by ANOVA (Pvalue < 0.05).…”

“…Based on Almeida et al (2016), the regression models used to estimate the properties through the density at 12% moisture content (ρ12), anhydrous density (ρs), and basic density (ρbas) are shown in Eqs. 1 through 4, where X is the independent variable (ρbas, ρ12, ρs), Y the dependent variable (ρbas, ρs, βr, βt, βl, βv, AC, αv/PSF, βv/PSF), and "a" and "b" are two parameters of the adjusted functions (Eqs.…”

“…The sampling was based on strength classes or classes of resistances (CR) with three species for each class, according to NBR7190 (1997), to obtain representative results, given the existing wide range of densities, as it has been emphasized by several authors, such as Almeida et al (2016). …”

Influence of harvest region on properties of Cambará wood

“…The apparent density of the wood, referring to the moisture content of 12 %, is a physical property of easy determination and this can be easily related to the properties of strength and rigidity from the use of mathematical methods. This is an alternative to reduce time and costs on properties determination (Christoforo et al 2014, Machado et al 2014, Dadzie and Amoah 2015, Almeida et al 2016, Christoforo et al 2017a.…”

Radial variation in tracheid lengths in dominant trees of selected coniferous species

“…Due to the structural variability of wood (both inter-and intra-species) its properties have been observed to fall within a wide range of values. Despite the considerable variability in its characteristics, wood is a valuable structural material that is also used as a raw material for the manufacture of wood-based boards and for the pulp and paper industry (Corson et al 2004;Cloutier et al 2007;Almeida et al 2016).…”