Effect of local stiffeners and warping constraints on the buckling of symmetric open thin-walled beams with high warping stiffness

Abstract Local stiffeners affect the behaviour of thin-walled beams (TWBs). An in-house code based on a one-dimensional model proved effective in several instances compressive buckling TWBs but gave counterintuitive results for locally stiffened TWBs. To clarify matter, we investigated with multi-symmetric double I cross-section, widely used practical applications where high bending stiffness is required. Several samples were manufactured and purpose, closing them over small portion axis at different places. The tested end constraints accounting various warping conditions. experimental numerical outputs from commercial FEM key to overcome unexpected by code, paving way further studies.