Effect of chord configuration and spacing on cyclic flexural response of built-up columns

Abstract

As per the current codes of practice, the design of battens of a built-up steel column depends on the level of axial load. These columns may not reach their plastic moment capacities under the lateral loading due to the premature instability of main chords in the expected plastic hinge regions. In this study, the cyclic performance of built-up battened columns is analytically evaluated under the gradually-increasing lateral displacements and the constant axial loads using a finite element software ABAQUS. The main parameters varied are the chord spacing, the column slenderness ratio, the level of axial load, and the chord configuration. Ninety-eight FE models of battened columns are analysed in this study in which the hot-rolled steel channel or I-Sections are used as the main chords. The analytical results showed that the built-up columns made up from I-sections have better lateral strength and ductility as compared to the Channel sections for nearly same values of axial load and slenderness ratio. Based on the analytical results, the limiting values of chord spacing, slenderness ratio and level of axial loads are proposed in order to delay the effect of instability on their lateral load resistance. Further, the interaction between axial load-moment capacity of built-up columns is discussed for various types of chord configurations.