Experimental study on mechanical behavior of RPC circular columns confined by high-strength stirrups under axial compression

Abstract

The axial compression mechanical behavior of Reactive Power Concrete (RPC) circular columns which confined by the spiral hoop of yield strength 600MPa are tested, and the tie spacing and volume tie ratio were used to evaluate the RPC columns failure modes, load-displacement relationship and yield characteristics of high-strength stirrups. The results show that the peak stress of the 250mm diameter circular column with no reinforcement can be up to 144.4MPa but with brittle failure mode, and the large volume tie ratio can increase the peak stress to 180MPa and failure by ductility; also, the high-strength spiral stirrups do not yield at the peak axial load, and the effective confined stress should be calculated according to the measured stirrups strain , and the remaining strength can be ensured the good ductility of the RPC specimens before reaching the ultimate failure mode; the peak strength and strain of RPC are proportional to linearly increase with effective confinement stress, but the proportion coefficient is smaller than that of ordinary concrete. The decline section of RPC stress-strain curve becomes smooth with the increase of effective binding stress, and the ductility coefficient of displacement gradually satisfies the ductility design requirements. The measured RPC stress-strain curve agrees well with the confined concrete Mander model and can be used conservatively. According to the test results, the calculation formula and the construction measurements of the axial compression capacity of the RPC with the spiral stirrup confined are put forward, which is convenient for the popularization and application of the confined RPC columns in the practical engineering.