Seismic behavior test and plastic hinge theory for HRB500 prefabricated steel reinforcement cage-cast-in-situ concrete columns

Abstract

An innovative method for constructing concrete columns has been proposed, namely utilizing the hot-forged double-lock mother combined mechanical sleeve connection for the HRB500 prefabricated steel reinforcement cage－cast-in-situ concrete (PRC-CISC) columns. The purpose of this method is to promote the industrialization of steel reinforcement projects and enhance the quality of structural construction. Two traditional reinforced concrete (RC) columns and four PRC-CISC columns were designed for quasi-static tests with design axial compression ratio (ACR) and reinforcement connection methods as parameters. Firstly, the results of the study showed that all specimens exhibited typical flexural failures, with well-rounded hysteresis curves, gradual stiffness degradation in the later stages, good ductility, and energy dissipation. Mechanical sleeve connections had a minor impact on the failure mode of PRC-CISC columns. Increasing the ACR improved the carrying capacity but reduced ductility, narrowed the hinge zone, and increased longitudinal bar stress. The effect of sleeve connection on energy dissipation, stiffness, ductility, and carrying capacity of the specimens was limited, and the overall behavior was stable and controllable. Furthermore, the carrying capacity and stress distribution of core area steel bars in traditional RC columns and PRC-CISC columns were further calculated to assess the differences. Finally, a two-stage plastic hinge calculation theory was formulated, which takes into account the influence of axial pressure, and construction recommendations for two types of PRC-CISC columns were provided.