Abstract：The dynamic tests of 81 recycled aggregate concrete (RAC) short columns confined by transverse hoops were carried out at an MTS 815 testing machine. The failure modes of confined recycled aggregate concrete (CRAC) under various strain rates were thoroughly analyzed. Based on the obtained measured stress-strain curves, the influences of the strain rate effect, the confinement effect, and the replacement percentage of recycled coarse aggregate (RCA) on the mechanical and deformation performance of CRAC were investigated. According to the influence law of the strain rate on the mechanical and deformation performance of CRAC, the dynamic increase factor (DIF) model of the performance index for CRAC was initially proposed. The influences of those factors, such as the type of the transverse hoop reinforcement, the spacing of the hoop set, the yield strength of the hoop reinforcement, and the volume ratio of the stirrups on the mechanical behavior of the CRAC short column were deeply analyzed. The confining increase factor (CIF) model of the performance index for CRAC was also preliminarily developed. The analysis results indicate that the confinement effect of the hoop reinforcement has an important influence on the mechanical and deformation performance of CRAC, and the ductility of RAC is improved significantly. By analyzing the influence of the replacement percentage of RCA, the replacement ratio influence factor (RIF) model was suggested. Based on the dynamic tests of the CRAC test units, the analytical model of the stress-strain relation for CRAC was proposed by applying the factors of DIF, CIF, and RIF to the characteristic parameters. The corresponding complete stress-strain curve equations of CRAC are developed and determined. The analytical curves and the experimental curves agree well, which indicates that the proposed analytical model is reasonably good. The results provide a significant research foundation for the dynamic nonlinear analysis and seismic optimum design of RAC structures.
