Closed-form solutions for FPR-to-concrete bonded joints with loaded-end anchorage: Insight into the interfacial shear transferring mechanism

Incorporation of end anchorage has not only proven to be an effective method for enhancing the low utilization rate of the expensive fiber-reinforced polymer (FRP) material in the application of flexural strengthening of reinforced concrete (RC) beams but also improving the poor ductility and low load-bearing capacity of the FRP-to-concrete interface. The shear transfer mechanism at the interface with free-end anchorage has been understood, but for the interface with loaded-end anchorage, the shear transfer mechanism remains unclear. In this paper, a new analytical model is present to elucidate the shear transfer mechanism of the FRP-to-concrete bonded joint with loaded-end anchorage, including the U-jacket, FRP anchor, and mechanical fastener. The analytical solutions are presented and compared with the finite element analysis (FEA) results, and the good agreement between them verifies the accuracy of the proposed model. A comparison of the load-slip curves is conducted for the FRP-to-concrete bonded joint under various conditions, including scenarios without any anchorage, with free-end anchorage, and with loaded-end anchorage. Finally, design strategies are put forth for multiple anchorages to improve the load-bearing capacity and ductility of the FRP-to-concrete interface.