THE INFLUENCE OF SPECIMEN DIMENSIONS IN DETERMINING THE CHARACTERISTIC STRENGTH OF WOOD BATCHES, CONSIDERING THEIR INCLUSION IN STRENGTH CLASSES RECOMMENDED BY ABNT NBR 7190:1997

• Grant number: 22/08996-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2022
• End date: September 30, 2023
• Field of knowledge: Engineering - Civil Engineering - Structural Engineering
• Principal Investigator: Francisco Antonio Rocco Lahr
• Grantee: Maira Rafaela Penazzo
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Wood is a material widely used in different fields, among the main ones being civil construction and, within it, the construction of structures, since it presents an advantageous relationship between strength and density, compared to other conventional materials for this use. In order to obtain the best responses in the use of wood, it is necessary that it be properly characterized. However, given the anisotropy and heterogeneity of wood, many properties need to be determined, which requires specific equipment and considerable time. In view of this fact, ABNT NBR 7190:1997 admits the convenience of simplifying the procedures for determining the properties of wood for structural projects. Thus, it allows that, from the characteristic values of the compressive strength parallel to the fibers (fco,k), the wood batches be classified into strength classes, according to chapter 6 of the mentioned normative document. Moreover, in its Appendix B, this standard indicates that fco,k can be estimated from the results obtained from specimens with a minimum cross section of 1.8 cm x 1.8 cm. In these circumstances, it is natural that doubts arise about the possible difference of results obtained in specimens with smaller dimensions than those indicated for the standard, which is the cross section 5 cm x 5 cm, and height 15 cm. To reduce the mentioned doubts, the present research project foresees the realization of tests in specimens with different dimensions from the standard and in different species of wood. As a conclusion it is expected the validation of the adoption of NBR 7190:1997 for the estimation of the characteristic strength from test specimens with dimensions smaller than the standard dimensions; or confirm the need to review this position of the Brazilian normative document.