Numerical analysis of seismic performance of steel-reinforced recycled aggregate concrete-filled square steel tube columns

Steel-reinforced recycled aggregate concrete-filled square steel tube columns (SSTSRRC) represent a novel composite structural form with excellent load-bearing capacity and energy dissipation performance, making them suitable for structures with high seismic requirements. However, numerical studies on the seismic performance of such composite columns remain limited, and the mechanisms influencing key parameters have not been fully elucidated. Therefore, based on previous research, this study establishes a three-dimensional finite element (FE) model using ABAQUS software, with validation against experimental results. The FE simulation accurately captures the hysteretic characteristics of test specimens, with the calculated ultimate load-bearing capacity deviating by less than 5% from experimental values. Parametric analysis reveals that increasing the strength of the square steel tube or steel reinforcement significantly enhances both load-bearing capacity and ductility, whereas the effect of concrete strength is relatively limited and may even reduce structural ductility. Additionally, an increase in the shear span-to-depth ratio leads to a decrease in both ultimate load-bearing capacity and energy dissipation capacity. Based on existing design codes and the moment superposition method, a calculation approach for the horizontal ultimate load-bearing capacity of SSTSRRC columns under combined compression and bending is proposed, achieving an average error of less than 10%.