A generalised analytical solution for the debonding prediction of FRP-to-substrate joints with different anchorage systems

Abstract

A generalised analytical model (GAM) is proposed for the debonding simulation of several bonded joints with dissimilar materials, particularly between fibre-reinforced polymer (FRP) and a structural material (e.g., concrete, steel, timber, or clay brick) with or without additional anchorages such as transversely compressed mechanical anchorage, FRP U-jackets, and FRP spike anchors, among others. These anchorages are simulated using axial springs that can exhibit linear or nonlinear behaviour and can be placed anywhere on the bonded joint, i.e., they can be used as an end or loaded anchorage, or placed somewhere between the FRP-loaded and unloaded ends. However, to define the springs, the corresponding load-displacement curves for each anchorage must be known beforehand. Nevertheless, if the local bond behaviour of the anchorage is known, a simple numerical strategy is proposed to estimate the load-displacement of the anchorage. This work considers a series of generated cases covering a wide range of situations. The results obtained from the GAM are compared with those obtained from a commercial finite element package, allowing validation. Several studies found in the literature were also analytically reproduced using the GAM. The analytical results were sufficiently close to the numerical and experimental data, regardless of the anchorage type (with linear or nonlinear load-displacement behaviour), or the location of installation along the bonded length. The mainstream results obtained from the Integral Absolute Error (IAE) were lower than 5 %. All results attested to the good accuracy, potential and versatility of the GAM to be considered and used in the future design of adhesively bonded structures.