Flexural buckling of thin-walled lipped channel columns with slotted webs: Numerical and analytical studies

Abstract In this paper elastic major-axis flexural buckling of thin-walled lipped channel column members with slotted webs is discussed. Though slotted webs are applied in order to enhance the thermal properties (this is why these members are also known as thermal studs), the slots have non-negligible effect on the mechanical behaviour. The primary aim of the presented research is to understand the behaviour, by identifying the major factors that influence buckling. As a tool, the recently developed constrained finite element method has been used, which makes it possible to separate the behaviour/buckling modes, as well as provides full control on the details of the calculations. It is found that, though other factors have some influence on the buckling results, the most important factor is the in-plane shear deformations of the slotted web, which may either be disregarded, or considered partially or fully in the calculations. An analytical model is also proposed for the calculation of critical force of slotted-web members, able to consider the effect of shear deformations, the degrading effect of the slots on the axial and bending rigidity, as well as the effect of longitudinal second-order strain terms. Numerical studies have been conducted covering a wide range of column lengths and slot geometries. The results of the numerical studies confirm the applicability of the constrained finite element method, and show that the analytical model estimates the critical loads with reasonable accuracy.