Study of the stability of weightless thin-walled straight columns under centrically applied terminal compressive force by using equivalent forces

Abstract

There are three possible modes of buckling of thin-walled straight steel columns: flexural buckling, torsional buckling, and flexural-torsional buckling. These modes of buckling are considered in the specification for the design of steel structures, such as Eurocode 3, which includes the particular case of torsional-flexural buckling of centrically loaded members with monosymmetric cross-sections. The system of differential equations that governs the stability of centrically loaded weightless members was presented in the mid-twentieth century and has been widely addressed in both steel structures and instability books. In this work, a simpler way to obtain the differential equations of stability for both torsional and flexural-torsional buckling modes by using equivalent forces is presented. The presented idea is especially useful in the academic context of civil engineering. Students and faculty members will appreciate the deduction of the instability equations governing the equilibrium in a few simple steps.