Interfacial Behavior of Carbon FRP-to-Granite Joints with Mechanical Fastening

Abstract

Premature debonding is a major obstacle for the utilization of fiber-reinforced polymer (FRP)-reinforced stone structures due to the brittle characteristics of stone materials. The study of the interfacial behavior between FRP sheets and stone materials with mechanical anchoring is critical when relative slip occurs at the joint interface. In this study, 45 single shear tests were performed to investigate the interfacial properties between FRP sheets and granite under static loading. Several variables were considered, including the differences in the FRP sheet stiffnesses and anchor properties (e.g., the number and spacing of fasteners, bolt torque, and bolt diameter). The failure modes, strain distribution, and load–slip curve of the designed specimens were discussed. The results indicate that compared with the external bonding (EB) method, the hybrid bonded FRP (HB-FRP) strengthening technology significantly improves the FRP usage efficiency, and the ultimate bond load and slip can be enhanced with an increase in the number of anchors and the torque. In addition, the stiffness of the FRP sheet and bolt diameter negatively influence the ultimate slip of the FRP sheet–granite interface, and the slip between the two anchors depends on the ratio of the effective bond length (EBL) and anchor space. These test results offer helpful information for designing HB-FRP reinforced stone structures.