&lt;b&gt;Shear and longitudinal modulus of elasticity in wood: relations based on static bending tests

Francisco Antonio Rocco Lahr,Victor Almeida De Araújo,Eduardo Chahud,André Luis Christoforo,Luciano Donizeti Varanda,Luiz Antonio Melgaço Nunes Branco

doi:10.4025/actascitechnol.v39i4.30512

Abstract

Improve quality of timber structures design is an aim that must be systematically sought by engineers in this area. An important topic that can contribute directly to be achieved in this subject is the more consistent knowledge related to structural properties of wood. Know values of longitudinal modulus of elasticity (E) and shear modulus (G) is essential for proper evaluation of plate structures performance, as example. It has been usual to adopt statistical equivalence for E and G values in plans longitudinal-radial and longitudinal-tangential, although experimental confirmation of this hypothesis is required. In this context, the aim of this work is to determine values of E LR , E LT , G LR and G LT , based on static bending tests, to five dicotyledonous species. Results showed statistical equivalence between the elastic properties in both plans, and the relation E = 35G was obtained for the five wood species here considered.

Highlights

Improve quality of timber structures design is a aim that must be systematically sought by professionals in this area
The specimens evaluated in experimental procedures were properly stored and tested in dependencies of Laboratory of Wood and Timber Structures (LaMEM), Department of Structural Engineering (SET), São Carlos Engineering School (EESC), University of São Paulo (USP)
Inclusion of these wood species in strength classes stipulated by NBR 7190 (ABNT, 1997) is based on the characteristic values of compression strength parallel to grain

Summary

Introduction

Improve quality of timber structures design is a aim that must be systematically sought by professionals in this area. Some normative codes in this matter adopt arithmetic relations to describe wood properties in order to make simple and quick the evaluation of structural elements behavior. Brazilian Code NBR 7190 (Associação Brasileira de Normas Técnicas [ABNT], 1997), some relations between longitudinal modulus of elasticity (E) and shear modulus (G) are adopted, but without appropriate experimental basis. This can induce to doubts in structural design and someone can take calculation assumptions that lead to imprecise estimation of stresses, as asserted by Bodig and Jayne (1982), Calil Junior, Lahr, and Dias (2003), Karlsen (1967), Mateus (1961), and Ritter (1990). Know values of longitudinal modulus of elasticity (E) and shear modulus (G) is essential for proper evaluation

Objectives

Methods

Results