Novel local buckling formulae for cold-formed C-section columns considering end condition effect

Abstract

It is well accepted that, for a long column, the effect of end conditions on the local buckling load can be ignored due to its less impact. However, such an assumption may be inappropriate for a stub column. According to the available literature, the research dealt with such a problem was found to be quite rare. In this scenario, this paper aims to derive novel local buckling formulae for cold-formed C-section column, which takes both the effects of cross-section plate element interactions and end conditions into account. Initially, an equivalent simplified web local buckling model was proposed, in which the cross-section plate element interaction of the flanges and the lips on the web were modeled by rotational springs and the loaded edges were assumed to be uniformly compressed and to be simply supported or fixed. Subsequently, based on the energy method and the theory of Bleich, explicit expressions for the local buckling load of the column were derived. Further, simplifications to the rigorous formulae were made to allow them to be easily used by the engineers. Finally, in order to verify the accuracy of the derived formulae, the results obtained from the derived formulae were compared with the numerical results obtained from the computer software CUFSM. The comparison results show that the formulae proposed in this paper can be used successfully in estimating the local buckling loads for pin-ended or fix-ended C-section columns with a practical length.