Elastic buckling of two-segment columns: analytical and computational study

Columns in compression with multi-segment, non-uniform or variable cross-sections are widely used in building engineering. The buckling problem presents a stability issue that resembles a limit state, whereby a compressed column deviates from elastic shortening within the original geometry and undergoes large deformations involving a change in member shape for a very small increase in load. However, these composed columns of two or more segments with different cross-sections require extensions of the classical Euler theory and careful numerical simulation. In this work, an analytical approach and a finite element method using Ansys® are used to calculate the elastic critical buckling load in columns with two-segment cross-section types. The analytical methodology is implemented using a differential equation solved with a variational iteration method and validated with an applied finite element method. Results are presented for different column types, considering rectangular and circular solid cross-sections, based on parametric studies across a range of dimensions and are intended to predict global elastic buckling of the column.