Elliptical hollow section steel cantilever beams under extremely low cycle fatigue flexural load - A finite element study

A comprehensive non-linear finite element (FE) study carried out on elliptical hollow section (EHS) steel cantilever beams of 1740 mm2 cross-sectional area and 1500 mm long under extremely low cycle fatigue (ELCF) uni-directional flexural load along major and minor axes separately is presented using the general FE package, Abaqus. The aspect ratio (major to minor axis diameter ratio), a/b and shell thickness, t of EHS beam models are varied between 1-2.33 and 4-6 mm respectively. The effect of a/b ratio and section slenderness on cyclic rotation capacity and flexural over-strength of the EHS FE beam models is investigated in this study. It is observed that the effect of a/b on rotation capacity under major axis bending is significant. Also, the cyclic flexural over-strength is not significantly affected by a/b ratio. New slenderness limits for circular hollow sections under bending are proposed. Modified slenderness parameters for EHSs under bending based on equivalent circular hollow section approach are derived. Empirical expressions for predicting cyclic rotation capacity and flexural over-strength of EHS beams are derived based on the FE study.