Numerical and experimental investigation of lateral torsional buckling of wood beams: Fid-Bau Portal

Numerical and experimental investigation of lateral torsional buckling of wood beams

Xiao, Q. / Doudak, G. / Mohareb, M.

Highlights•This paper reports on the results of a full-scale experimental and numerical study aimed at investigating the elastic lateral torsional buckling capacity of wooden beams.•A full-scale bending test is conducted on 18 lumber joist elements to determine their elastic lateral torsional buckling resistance.•A 3D finite element model was developed which included orthotropic material representation based on properties of the joist components determined in non- destructive tests.•The model provides a realistic representation of boundary conditions and loading details in the tests.•The FEA model is observed to reliably predict the elastic lateral torsional buckling capacity of beams.•The reliability of the finite element model is assessed through comparisons with full-scale test results.•The validated model was then used to assess the Eurocode provisions regarding lateral torsional buckling of wooden beams.•The study found that for simply supported end conditions the code equation seemed reasonable and slightly conservative.•For cantilevered beams, the Eurocode provisions were overly conservative for the case of bottom edge loading and non-conservative for the case of top edge loading.•Changes have been proposed to the wording of the effective length adjustment factor and the results based on the revised definition provided critical moment predictions that were conservative and more consistent for cantilevers under top and bottom edge loading.

AbstractThe present study reports the results of a full-scale experimental and numerical investigation aimed at predicting the elastic lateral torsional buckling capacity of wooden beams. The experimental component consists of 18 Spruce-Pine-Fir (SPF) No. 1/No. 2 grade lumber joists consisting of five 38mm×184mm×4200mm, six 38mm×235mm×3600mm, and seven 38mm×286mm×4200mm specimens. For each specimen, the shear and longitudinal elastic moduli are first determined experimentally through non-destructive tests. A full-scale bending test is then conducted on each specimen, to determine its elastic lateral torsional buckling resistance. A 3D finite element model is developed to predict the lateral torsional buckling resistance for each specimen based on the experimentally determined shear and longitudinal elastic moduli. The validity of the finite element analysis is assessed through comparisons with full-scale test results. The validated model was used to assess the Eurocode provisions and it was found that for simply supported end conditions the code equation seemed reasonable and slightly conservative. However, for cantilevered beams, the Eurocode provisions seem to be overly conservative for the case of bottom edge loading and non-conservative for the case of top edge loading. Changes have been proposed to the wording of the effective length adjustment and the results based on the revised definition provides critical moment predictions that are conservative and more consistent for cantilevers under top and bottom edge loading.