Experimental study on axial compressive behavior of steel tube‐reinforced recycled aggregate concrete composite columns with steel bars

Abstract

AbstractIn this paper, five specimens were designed to test under monotonic static loading to study the axial compression performance of steel tube‐reinforced high‐strength recycled aggregate concrete composite columns with steel bars. The design parameters for these specimens include the type of concrete, the sectional shape of the steel tube (circular or square), and the internal structure of the core column, specifically the presence or absence of cross‐shaped tie bars in the square steel tube. The effects of different parameters on the axial load–displacement curve, bearing capacity, and ductility were analyzed. The test results show that the failure of all specimens was caused by the concrete cover spalling of outer reinforced concrete, which occurred after the longitudinal strain of the steel tube exceeded the yield strain. The ultimate bearing capacity of the recycled aggregate concrete (RAC) specimen is higher than that of the natural aggregate concrete (NAC) specimen, but the latter has a more robust deformation performance. Furthermore, under the condition of the same steel tube cross‐sectional area and similar material strength, the bearing capacity and deformation capacity of specimens with circular steel tubes are higher than those of specimens with square steel tubes. A similar conclusion was also obtained for square steel tube specimens with cross‐shaped tie bars. Finally, four international design methods were applied to estimate the axial compression capacity of 40 composite columns, as detailed in this paper and other sources.