The Constitutive Relationship of Concrete Core in Circular Concrete-Filled Steel Tubular Columns

Considering the confining mechanism in circular concrete-filled steel tubular (CFST) columns, a volume-based method for dividing the effectively and ineffectively confined area of concrete core and calculating the value of effectively confined coefficient is presented. The constitutive relationship of concrete core is developed by means of modifying the expressions of effective lateral pressure and the descending stage in Mander’s confined concrete model. Numerical simulation of several circular CFST columns under axial load is carried out in ABAQUS. The comparisons between calculated results and experimental results demonstrate that the suggested concrete constitutive relationship is appropriate for the nonlinear analysis of circular CFST columns.