INFLUENCE OF MOISTURE CONTENT ON PHYSICAL AND MECHANICAL PROPERTIES OF Vatairea SP WOOD

Heloiza Candeia Ruthes,Fernando Júnior Resende Mascarenhas,Iuri Fazolin Fraga,Vinícius Borges De Moura Aquino,Felipe Nascimento Arroyo,Francisco Antonio Rocco Lahr,André Luis Christoforo,Larissa Soriani Zanini Ribeiro Soares

doi:10.1590/1806-908820220000006

Abstract

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.

Highlights

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 provides the classification of hardwoods according to their characteristic strength
The results showed that the mean values of the compressive strength parallel to grain, tensile strength parallel to grain, shear parallel to grain, flexural modulus of strength, and modulus of elasticity in parallel compression were higher for the moisture content of 12 % than when the samples were saturated
Regarding the classification of Vatairea sp. wood, the characteristic value obtained for the compressive strength parallel to grain was 49.91 MPa (Equation 3); the wood of this species belongs to the C40 hardwood class according to NBR 7190 (ABNT, 1997)

Summary

Introduction

The use of wood to manufacture structural elements and structures is widespread, especially in Europe and North America, mainly in buildings with less than six floors and no complexity. The lack of knowledge about wood species' strength and stiffness properties with potential use in structures contributes to a safer and more conservative design. Several species have been investigated to verify their properties and behavior in response to load carrying. Wood that belongs to the group of hardwoods, which are heavy and hard woods, with yellowish-brown color and a strong bitter taste. It is found mainly in the north and central-west regions (IPT, 2021). Wood is used mainly in the structure of apparent roofs with high loads and large spans Vatairea sp. wood is used mainly in the structure of apparent roofs with high loads and large spans

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