Wood is an anisotropic material and its resistance characteristics vary with the angle between the effort and the fiber direction (α). The Brazilian Code NBR 7190 - Design of Wooden Structures, foresees the strength correction to the normal stress, whenever α > 6o, and it recommends to apply Hankinson's expression to design values. However, this referred code is omitted about this correction to the tangential stress. Besides, there is not experimental confirmation about the validity of using this expression on design values, originating from characteristic values. The objectives of this work were: to search in the bibliography other used expressions; to verify the validity of these expressions, to represent the variation of the shear strength, with the α angle; and, to verify the validity of application of these expressions in characteristic values. For this, a sample formed by twelve boards was used. From each board, specimens to shear tests were retired, with different fibers inclinations, which were tested in agreement with current NBR 7190, supplying the shear strength, for different α values. Four models (Hankinson, Sin, Karlsen and Keylwerth) were evaluated, using the pairing and deviation tests. The model that best represented the phenomenon, in both cases, was Keylwerth's.
shear strength; characteristic strength; fibers inclination
