Equivalent imperfections for the out-of-plane stability design of steel beams by second-order inelastic analysis

In current structural design specifications, such as EN 1993-1-1 for steel and 1993-1-4 stainless steel, the stability of members is typically assessed through use buckling curves, which consider influence initial geometric imperfections residual stresses. An alternative, more direct, approach to perform either an elastic or inelastic second-order analysis member structure with imperfections. For modelling convenience, so-called ‘equivalent’ are utilised, combined both Equivalent columns beams by analysis, also referred geometrically nonlinear imperfection (GNIA), provided in specifications. columns, equivalent materially (GMNIA), were recently developed, but that susceptible lateral-torsional (LTB), there currently no appropriate provisions. The aim this study therefore develop out-of-plane GMNIA. proposals calibrated against results benchmark finite element (FE) simulations performed on a large number stresses subjected major axis bending. Two amplitudes developed: (1) e0,mod, eigenmode-affine (2) e0,bow, sinusoidal bow latter applied solely lateral direction summation half-sine wave full-sine wave. Relative traditional Eurocode calculations, employing proposed LTB GMNIA provides generally accurate resistance predictions, while remaining safe-sided relative FE results. reliability provisions demonstrated statistical where it shown partial safety factors 1.0 1.1 can be safely adopted.