Experimental Study on Seismic Performance and Non-Equal Calculation Method for Prefabricated Reinforced Cage—Cast-In-Situ Concrete Columns

To promote the industrial development of reinforced concrete engineering and enhance the construction quality of prefabricated buildings, an innovative partial prefabricated construction method is proposed in this paper, namely the prefabricated reinforced cage–cast in situ concrete (PRC-CISC) structure with an innovative steel bar connection technology. The connection techniques, including direct thread rolling of steel bars and hot-forged sleeves, are adopted. With the design axial compression ratio and the layout of couplers in the reinforcement cage as the main parameters, quasi-static tests are carried out to investigate the failure mode, seismic behavior, and mechanical mechanism of couplers of PRC-CISC columns. The results indicate that all specimens present typical compression–bending failure with plump hysteretic curves, gradual stiffness degradation, good ductility, and energy dissipation capacity. The new couplers can effectively satisfy the seismic performance requirements of PRC-CISC columns. With the increase in axial compression ratio, the bearing capacity rises while ductility decreases, and the stress of longitudinal bars increases. The layout of couplers exerts a controllable influence on the mechanical and deformation performance of specimens. The steel stress in the core stress region of PRC-CISC columns shows a bilinear distribution with stress concentration at both ends of the sleeves, which is related to the material difference in couplers. Finally, two “non-equal” calculation methods (plastic hinge model and fiber model) are established based on experimental results and finite element analysis, forming a systematic calculation theory for the new material–new technology–new structure system. The research provides important references for the engineering application of such structures.