Using non-destructive testing to predict the mechanical properties of glued laminated poplar

This paper describes the use of non-destructive methods to assess the mechanical properties of structural glued laminated timber (GLT) made from poplar. The longitudinal vibration method (LVM) and the transformed section method (TSM) were considered. Full-scale tests were also performed to determine the most relevant mechanical properties of 18 beams, namely modulus of elasticity and bending strength. In addition, the bonding performance of each beam was checked by delamination and shear strength tests. Detailed analysis of the results was performed and combined with Levene and Tukey tests. The accuracy of the two non-destructive test methods was evaluated by linear regression analysis. The TSM showed stronger correlations with modulus of elasticity and shear strength. Slightly lower values were obtained using the LVM. A strength class of GL24c can be assigned for GLT made from poplar, with lower properties at the inner lamellas.