Experimental study on the axial compressive performance of prefabricated steel reinforcement cage‐cast‐in‐situ concrete column with an innovative sleeve

Abstract Based on the ribbed rebar with direct rolling thread and hot‐forged double‐lock nut mechanical sleeve connection technology, a construction method for prefabricated reinforcement cage‐cast‐in‐situ concrete (PRC‐CISC) column using this connection is proposed. This method contributes to improving the construction efficiency and engineering quality of reinforced concrete columns. Four PRC‐CISC columns and four control specimens were designed with rebar strength, rebar ratio, and rebar connection method as analysis parameters. A comparative study was conducted on their failure modes, axial compression performance, and rebar connector (coupler) working mechanisms. The results show that compared to the control specimens, the crack morphology of PRC‐CISC columns has no significant difference. However, the apparent yielding position of the reinforcement cage may occur on the cross‐sections where the rebar is located on both sides of the sleeve. The partial carrying capacity of the specimens may increase or decrease (≤4.08%), and the maximum deviation of the displacement ductility coefficient is 0.14, indicating that its strength and deformation differences are relatively small. Furthermore, the study reveals the random migration behavior of the control section of PRC‐CISC columns. When the specimens fail, the strain of the sleeve is significantly smaller than the rebar strain in the control specimens, while the concrete strain shows no significant difference. This is because the increase in the effective area of the sleeve shares the vertical load it bears. Finally, based on the test results, sleeve constitutive relationship, and random migration behavior of the control section, the compressive load capacity range of the positive section of PRC‐CISC columns is proposed. This method can effectively estimate their actual carrying capacity and is consistent with the force characteristics.