APPARENT DENSITY AS AN ESTIMATOR OF WOOD PROPERTIES OBTAINED IN TESTS WHERE FAILURE IS FRAGILE

Abstract

ABSTRACT The use of new wood species in construction requires knowledge of their properties for safer and more economical structural sizing. In Brazil, structural projects are carried out according to the standard document ABNT NBR 7190:1997. Tests required by this standard for the complete characterization of species require large machines with high costs, which are present only in large research centers. Considering the lack of experimental determination, this study aimed, with the help of analysis of variance of regression models, to investigate the possibility of estimating, through apparent density, wood properties obtained in tests where failure is considered fragile, allowing the estimation of properties of species still little used. Ten wood species belonging to the hardwood group (cambara, cedro, cedrorana, copaiba, angelim-araroba, castelo, oiticica-amarela, guarucaia, guaicara, and garapa), covering all strength classes established in the standard ABNT NBR 7190:1997, were used. The results showed that shear strength parallel to the grain (fv0) was the only property that could be estimated by apparent density (ρ12), with an R2 above 50%. Tensile strength normal to the grain (ft90) and splitting strength (fs0) showed poor fit quality.

Keywords

• hardwoods
• fragile failure
• regression models
• analysis of variance