Modified equation for stability computation of round HSS beam–column subject to biaxial moments

This paper presents the study on equations for stability capacity computation of round hollow structural section (HSS) beam–column subject to axial compression and biaxial moments about two principal axes. By the comparison of numerical results with design interaction formula in major design codes around the world, it is shown that existing design interaction formulas have limitations in stability capacity calculation of HSS beam–column under biaxial moments. Based on theoretical and numerical analysis, an alternative method together with a modified equation is proposed to predict the stability capacity of round HSS beam–columns. The modified equation is verified to be accurate and applicable to various biaxial moment distributions.