Nonlinear Analytical Solution for End Debonding Simulation of CFRP-to-Steel Joints with an End Anchorage

Carbon fiber-reinforced polymers (CFRPs) have been widely used as reinforcement material for degraded structures in the past few decades. However, the CFRP composite is prone to premature debonding from steel substrates. To delay or even prevent its premature debonding from flexurally strengthened beams, additional anchorages are usually added at the end of the CFRP-To-steel joint. Therefore, the loads transmitted to the CFRP composite can be increased, but the debonding process changes when compared with the case where no additional anchorages are used. Based on the single-lap shear test, a new analytical solution is developed to facilitate the understanding of the debonding process of CFRP-To-steel joints with (or without) a transversely compressed end anchorage, exhibiting linear or nonlinear behavior, which demonstrates its wide-ranging application. Because it is simple to integrate and derive, a well-known exponential bond-slip relationship is used in the proposed analytical solution. To validate it, a series of generated cases is studied, and the results are compared with those obtained from the FEM and from the finite difference method. The load-slip curves, CFRP strains, and bond stresses developed throughout the bonded length obtained in all the methods are compared. To consider the influence of the compression stresses on the hybrid bonded FRP-To-steel joints, a new bond-slip relationship is proposed, which considers the influence of Mode I (due to external compression) on Mode II through the Mohr-Coulomb failure criterion.