Closure to “Axial Load Design for Concrete Filled Steel Tubes”

Abstract

The ultimate load of axially loaded concrete filled steel tube columns was investigated and design equations are proposed which are based on summing the tangent modulus buckling loads of the concrete core and the steel tube. The tangent modulus loads are calculated using the AISC code method for the steel tube and a parabolic stress-strain relationship for the concrete. The proposed design equations are shown to give reasonable agreement when compared with test results and it is shown that other design formulae do not give better agreement. A method for calculating the limits of slenderness ratio which determine whether an increase in concrete strength due to triaxial confinement is likely is also given.