Stability of stiffened cold-formed steel I-sections using the bubble finite strip method

This paper proposes a semi analytical complex finite strip method using bubble functions to study the local, distortional and global buckling of stiffened as well as unstiffened cold formed steel I-sections under compression and bending loading conditions. The method is programmed and used to investigate the elastic buckling of mono and doubly symmetric I-sections containing longitudinal flange stiffeners. The effect of longitudinal flange stiffeners on the stability of cold-formed I-section members is surveyed. Furthermore, a comparison between stiffened and unstiffened cold-formed I-sections is made for different buckling modes. The accuracy of bubble finite strip method in predicting the buckling stresses of monosymmetric cold-formed I-section beams in comparison with Generalized Beam Theory (GBT method) will be established. Case studies are performed for different geometric properties of the sections and the stiffeners on the buckling strength of cold-formed steel I-sections