Numerical studies on creep behaviour of SRCFST columns with initial stress of steel tube

The long-term creep behaviour of steel-reinforced concrete-filled steel tubular (SRCFST) column under whole life cycle is a key issue in engineering design. Therefore, a finite element (FE) analysis based on ABAQUS software is conducted to study the creep performance of SRCFST columns considering the initial stress of steel tube. Based on the verified FE model, the whole process load-deformation curves, load distributions of each component and longitudinal strain versus time curves are obtained. The stress distributions of each component are analyzed at the feature points. The effects of main parameters on the creep behaviour are studied, including the sustained load level, initial stress ratio, compressive strength of concrete, steel ratio of steel tube and encased steel section. The studies show that the SRCFST member exhibits an elastoplastic behaviour subjected to the coupling effect of initial stress on steel tube and sustained load. However, the creep ratio undergoes a change from linear to nonlinear by increasing long-term load or initial stress ratio. Finally, a method for calculating the creep in SRCFST columns under combined loads is provided, and the long-term performance can be better predicted.