Numerical modelling of bond mechanism of ETS FRP bar‒concrete joints with long embedment length

In this study, the bond behaviour between the embedded through-section fibre-reinforced polymer (ETS FRP) bars and concrete is investigated using nonlinear finite element (FE) analysis. The pull-out scheme for the investigation of the interfacial interaction of ETS FRP bars adhesively bonded to concrete is presented. The proposed numerical study also considers the ETS FRP bar‒concrete joints with long bond (embedment) length. First, a trapezoidal bond model describing the bond stress‒slip curves of ETS FRP‒concrete interfaces is adopted. Second, nonlinear FE models incorporating the developed bond model analysing the bond behaviour of the ETS FRP bar‒concrete joints are validated against the pull-out test results. The reliable FE models are then used in a parametric study to investigate the effects of key features, such as the properties of adhesives, FRP bars, and concrete, on the bond performance of the ETS FRP bar‒concrete interfaces. The analyses demonstrate the effectiveness and accuracy of the FE models. Expressions for the maximum bond force and the effective bond (embedment) length are rationally formulated based on the parametric study.