Investigating the mechanical behavior of 600 MPa rebar grouted sleeve connection with UHSGM

[Abstract] The grouted sleeve connection is a critical technology for splicing rebars in precast concrete structures. However, conventional grouting materials and sleeve configurations often fail to fully utilize the strength potential of high-strength rebars, leading to issues such as bond-slip and compromised connection reliability. This study systematically investigates the mechanical behavior of sleeve connections with the aim of optimizing their design of sleeve connections using 600 MPa high-strength rebars and ultra-high-strength grout material (UHSGM) through integrated experimental and finite element (FE) analyses. First, six grouted sleeve connection specimens with varying anchorage lengths and grout strengths were designed and subjected to monotonic tensile tests. Their load-displacement responses, strain distributions in the rebars and sleeves, and failure modes were recorded. Subsequently, fifteen parametric FE models were developed in ABAQUS to analyze the influence of anchorage length, number of sleeve ribs, and grout strength on connection performance. The results indicate that, with the exception of the specimen featuring an anchorage length of 6d and a grout strength of 85 MPa, which underwent failure due to rebar pull-out, all remaining specimens experienced rebar necking. Increasing the anchorage length to 10d significantly improved anchorage capacity and controlled slip deformation. Higher grout strength effectively enhanced the interfacial bond and promoted enhanced composite action among the components. Furthermore, the FE analysis provided deeper insight into the mechanisms governing failure mode transitions under various parametric conditions. This study offers valuable experimental data and a theoretical basis for designing and applying 600 MPa high-strength rebar grouted sleeve connections.