Tensile performance of UHPC-filled grouted corrugated duct connection for large-diameter rebars in prefabricated canopies

Grouted corrugated duct connection (GCDC) is an effective connection method for prefabricated structures. To facilitate the use of large-diameter rebars with short anchorage length in prefabricated canopies on the railway platform, a novel Ultra High-Performance Concrete (UHPC)filled grouted corrugated duct connection (UGCDC) was proposed. Tensile experiments were conducted on specimens using the anchorage length, the grouting material type, and the rebar diameter as research parameters to evaluate the tensile performance of UGCDC. The influence of parameters on bearing capacities, failure modes, rebar strains, and corrugated duct strains was compared and analyzed to reveal the force transmission mechanism of the UGCDC. Combining experimental results and theoretical analysis, a simplified equation for predicting tensile bearing capacity of UGCDC was developed, and a normalized bond-slip constitutive relation model of UGCDC was proposed. The results indicate that UHPC can reduce the anchorage length of rebar due to its superior mechanical properties, and the large-diameter (25 mm) rebar requires a critical anchorage length with 10d. The proposed model can predict the bond-slip constitutive relation of UGCDC accurately. Finally, a finite element model considering the bond-slip effect was established by using the normalized bond-slip model, which can accurately predict the forcedisplacement curve and failure mode of UGCDC. Finally, a parameter analysis was conducted to analyze the impact of rebar position and adjacent of surrounding rebars on the tensile performance of UGCDC.