Theoretical, experimental and numerical study of lateral buckling in glued laminated timber beams

Abstract

There is an upward trend in the use of glued laminated timber in increasingly slender structures, which requires special attention to instability effects, such as lateral buckling. This article presents the results of lateral buckling loads from an experimental campaign focusing on specimens with a relative slenderness greater than 1.4 (elastic range) and involving a total of 14 beams - 10 with constant depth and 4 with variable depth. These results are then compared with those obtained using the Eurocode, which does not account for the influence of knots and fiber deviation, and a numerical finite element model for validation. All tested beams exhibited an initial misalignment within the tolerances allowed by the Eurocode to analyze its influence. For the testing campaign, a novel loading system was designed, enabling more precise experimental results. From the results, the initial misalignment value was correlated with the loss of lateral buckling load capacity due to the stress exhaustion caused by the transverse displacement of the beam prior to instability. The article proposes a modification to the Eurocode formulation for calculating the critical lateral buckling load, incorporating this effect for slenderness within the elastic range.