Research on eccentric-compressive behaviour of steel-fiber-reinforced recycled concrete-filled square steel tube short columns

This study, a total of 25 specimens, aims to assess the influence of the mass replacement percentage of recycled coarse aggregates (0%, 50%, 75%, and 100%), steel tube thickness (3 mm, 4 mm, and 5 mm), load eccentricity (0.10, 0.25, and 0.40), and volume fraction of steel fiber (0%, 0.6%, 1.2%, and 1.8%) on the eccentric-compressive behaviour of steel-fiber-reinforced recycled concrete-filled square steel tube short columns. The post-peak mechanical behaviour, deformation ability, and energy consumption degrade with increasing mass replacement of recycled coarse aggregate; the load eccentricity is detrimental to the ultimate compressive strength and aggravates the lateral deflection; thicker steel tubes and the incorporation of steel fiber improve the ultimate compressive strength, deformation ability, and energy consumption. Moreover, an incremental iteration model is proposed to calculate the ultimate compressive strength of steel-fiber-reinforced recycled concrete-filled square steel tube short columns under eccentric-compressive load. Compared to current codes, the predicted values using the proposed model are close to experimental values and are inclined toward the safe side.