Shear and longitudinal modulus of elasticity in Corymbia citriodoraround timber beams

Vértices

Francisco Antonio Rocco Lahr¹  André Luiz Zangiácomo²  André Luis Christoforo³ 

[1] Escola de Engenharia de São Carlos da Universidade de São Paulo (EESC/USP);Universidade Federal de Lavras (UFLA);Universidade Federal de São João del-Rei (UFSJ);

关键词: Stiffness. Bending. Beams theory.Least squares method.;   

DOI  :  10.5935/1809-2667.20130006

来源: DOAJ

【 摘 要 】

This study aimed to evaluate, with the support of the three points static bending test, led nondestructively, the values of the shear (G) and longitudinal (E) modulus of elasticity in Corymbia citriodora structural round timber beams in order to verify the validity of the G=E/20 relationship established by the Brazilian standard ABNT NBR 7190:1997 (Design of Wood Structures). The specimens tested (20) have an average length of 750 cm, diameter of 30 cm, moisture content of 12% and 5% of average taper. There were two bending tests per element, with differences in the distances between supports. In the first trial, we used the L/D ratio between the length (L) and diameter (d) of the pieces equal to twenty-four, while the second was conducted in sequence, with L/d equal to fifteen. The elasticity modulus were obtained according to the successive use of the equation of Timoshenko’s beam theory, which takes into account the influence of the shear efforts to determine displacements. The results between the shear and longitudinal modulus of elasticity were related by the least squares method, the relationship G=E/56 was found, which demonstrates divergent results with the Brazilian standard for the structural round timber investigated.

【 授权许可】

Unknown