Parameter analysis and performance on RACFSST columns under eccentric compression

To study the performance degradation rule of recycled aggregate concrete filled square steel tube (RACFSST) columns under eccentric compression loading, 15 specimens with different replacement ratio of recycled coarse aggregate, slenderness ratio and eccentricity were tested under the monotonic static loading. On this basis, the evolutionary process of ductility, energy consumption and stiffness degeneration were analyzed. The results show that the bearing capacity of RACFSST columns is lower than that of square steel tube concrete columns, and that its ultimate bearing capacity decreases with the increase of slenderness ratio and eccentricity. The energy consumption of axial compression specimens goes up after dropping along with the increase of replacement ratio and decreases with the increase of slenderness ratio, while the energy consumption of eccentric loading specimens reduces with the increase of replacement ratio and increases with the rise of slenderness ratio. The energy consumption capacity of specimens increases with the rise of eccentricity, and the ductility indexes of specimens decrease with the increase of replacement ratio. Elastic stiffness drops after going up along with the increase of replacement ratio and decreases along with slenderness ratio and eccentricity rise.