Analytical framework for the substitution of steel-concrete composite columns with equivalent steel columns in structural design

The present work presents a mathematical framework to simulate steel-concrete composite columns with equivalent steel columns. A total number of three simulation methods are presented, in order to simulate circular and rectangular concrete-filled hollow sections, as well as concrete-encased I-shaped sections with steel columns of similar shape. The simulation is achieved by the satisfaction of three equations regarding their (a) axial resistance, (b) flexural stiffness about the major axis and (c) flexural stiffness about the minor axis. Solution of the aforementioned provides the dimensions of the equivalent steel sections as functions of the characteristics of the steel-concrete composite sections (a) in a closed form for all hollow sections and (b) in a high-accuracy approximate solution for I-shaped sections. The accuracy of the proposed methods and their general applicability are evaluated. The results yielded are indicative of the effectiveness of the proposed methods.