Ultimate capacity of axially loaded thin-walled tapered columns with doubly symmetric sections

The behaviour of thin-walled I-section tapered members is governed by the width–thickness ratio of the plate elements along with the member slenderness and tapering ratios. The effect of this interaction has been studied theoretically in this work. A nonlinear finite element model which allows for geometric non-linearities is constructed for the study. Large number of members having different values of flange and web width–thickness ratios along with different member lengths and tapering ratios were selected to draw complete ultimate strength–slenderness ratio curves and to study the different modes of failure. A series of curves were drawn for design purpose. Finally, an empirical equation to get the ultimate axial capacity of tapered slender I-section members (using the whole section) is presented. The equation alleviates the current complexity in the calculation of the effective width, providing more flexible design procedure.