Relationship between Characteristic Values of Shear Strength Parallel to Grain and Tensile Strength Perpendicular to Grain for Tropical Woods

Wood, due to its complex anatomy, requires meticulous characterization that imposes several tests to be carried out to evaluate its properties. Normative codes adopt different specimens to this aim. Geometric specificities proposed by NBR 7190-3:2022 and ASTM D143-22 to specimens used for estimating wood strength in tensile perpendicular to grain (f(t90)) make them difficult to carry out. Thus it is advisable to consider relating f(t90) with another mechanical property, for example, the shear strength parallel to the grain (f(v0)). This paper aims to establish a coefficient relating the characteristic values of f(t90) and f(v0), for strength classes D40 and D60 (frequently used for structural purposes) of Brazilian Code 7190:3-2022. A further aim, if possible, is to determine a single representative coefficient for both classes. Tests made it possible to obtain those properties for four species from each class, following NBR 7190-3:2022 guidelines. The optimal coefficient was determined using the least squares method (MMQ). Ratios f(t90,k)/f(v0,k) were 0.22 and 0.19, for classes D40 and D60, respectively. As these ratios don't present a significant difference, it is viable to adopt a single relationship for both classes, thus simplifying characterization procedures.