Strength modelling of Laminated Veneer Lumber (LVL) beams

Abstract

This paper develops a mechanical model to accurately predict the strength of Laminated Veneer Lumber (LVL) beams, and illustrates its applications to numerically predict the strength distribution of LVL beams manufactured from veneers rotary peeled from early to mid-rotation subtropical hardwood plantation logs. This resource is not traditionally used in the manufacturing of commercialised LVL beams. In the first part of the paper, the model is described, calibrated against experimental results performed on 8-ply LVL beams and then verified against experimental results performed on 13-ply LVL beams. Results show that the model is able to accurately reproduce the experimental results, both on flat and edge bending, with an average prediction-to-experiment ratio of 1.0 and a relatively low coefficient of variation of 0.10. A sound prediction of the non-linear behaviour of the beams before failure was also observed. In the second part of the paper illustrating the applications of the model, the mechanical properties of veneers analysed by the authors in a previous work are used as input values in the numerical model to predict the strength of six commercially available LVL beam sizes, manufactured from early to mid-rotation subtropical Gympie messmate (Eucalyptus cloeziana), spotted gum (Corymbia citriodora) and southern blue gum (Eucalyptus globulus) plantation veneers. The design strength (5th percentile) of the beams, obtained by Monte Carlo simulations, is reported and found to range from 32.3 MPa to 97.2 MPa, depending on the quality of the veneers used and the beam size. The LVL beams have design strengths comparable to, and in some cases up to 2.5 times higher than commercially available softwood LVL beams, making them attractive structural products. The strength variability is also reported in the paper for developing probability-based limit state design criteria in future studies.