Lateral instability of elliptical hollow section beams

Lateral instability of elliptical hollow section (EHS) members in bending is studied in this paper. Eight laterally unrestrained EHS beams, with a constant cross-sectional aspect ratio of two, were tested in three-point bending. The test set-up, material properties, section geometry, residual stress measurements and full load-deformation responses of the test specimens are reported herein. To supplement the experimental data, numerical models were also developed and validated against the test results. Parametric studies were then performed, to assess the influence of cross-sectional aspect ratio and member slenderness on lateral stability. Based on the assembled structural performance data, lateral torsional buckling curves for elliptical hollow section beams have been developed and statistically verified. Limiting lengths below which lateral torsional buckling (LTB) need not be considered have also been proposed.