Hencky Bar-Chain model for buckling analysis of non-symmetric portal frames

This paper presents the development of the Hencky bar-chain model (HBM) for the buckling analysis of non-symmetric portal frames under vertical compressive axial loads on the columns. Generic stiffness and geometric matrices are derived for the frame buckling analysis. Based on these matrices, a simple computer code is developed to determine the buckling loads. Illustrative frame buckling problems are solved to demonstrate the ease and simplicity of the HBM for analysis of different and complex design conditions imposed on the frames. The advantages of consistent formulation, localized model modifications, and convenience in obtaining the buckling modes are further noted for the HBM.