Reliability of Externally Bonded FRP-to-Concrete Joints with Epoxy Interlocking Enhancement

It has been proved that external bonding of fiber-reinforced polymer (FRP) composite materials with epoxy interlocking (EB-FRP-EI) enhancement could significantly improve the strength of FRP-to-concrete joints from experimental studies. However, there still exists a barrier to comprehensively implementing the EB-FRP-EI method in practical applications, owing to the lack of full reliability-based design guidelines with consideration of the uncertainty raised from materials, model errors, and loading. In this study, a numerical function of bond strength for EB-FRP-EI was derived by taking both the adhesion effect and mechanism doweling enhancement into account. The reliability analysis of the EB-FRP-EI method was conducted by utilizing the first-order reliability method (FORM). Corresponding to the required reliability index, two-parameter (groove depth and number) reliability-based design was performed for 35 (7 x 5) FRP-to-concrete joints in total. The effects of design and modeling parameters, including depth of grooves, number of grooves, thickness of FRP, width of FRP, and strength of concrete, on reliability performance of the bond strength of FRP-to-concrete joints with epoxy interlocking enhancement are presented and discussed. As a result, this study provides suggestions for the proper design of FRP-to-concrete joints with epoxy enhancement based on these parameters.