Numerical simulation and design method of the interface of UHPFRC-strengthened RC structures using post-installed rebars

Abstract

The interface using post-installed rebar (PR) connections has been proven to possess robust mechanical properties for strengthening reinforced concrete (RC) structures with ultra-high performance fiber reinforced concrete (UHPFRC). However, current studies have not yet clarified the design method for this type of interface, which significantly hinders its widespread application. To this end, this study is devoted to developing a design method for the interface of UHPFRC-strengthened RC structures using PR connections. Detailed finite element (FE) models were established to capture the interfacial performance, and their accuracy was verified using the experimental data. An extensive parametric study was performed to identify the essential factors for interfacial performance. The FE results revealed that the concrete between the rebars failed before the rebars when the post-installed rebar spacing was three times the diameter of the rebar. Moreover, it was found that the thickness of the UHPFRC layer had a negligible influence on interfacial shear strength. The detailing requirements for the interfacial design using post-installed rebars were given. Combining the experimental and numerical findings, a design method was proposed for the interface of UHPFRC-strengthened RC structures using PR connections. An existing experimental study on RC beams strengthened by UHPFRC was chosen to examine the applicability of the proposed design method. It was found that the well-designed beam exhibited good ductility and energy dissipation capacity. The perfect bond was proved to be acceptable for analysis simplification when the UHPFRC-strengthened RC structures were well-designed by the proposed method.