The bond behaviour between fibre reinforced polymers (FRP) and concrete plays a critical role in FRP-strengthened concrete structures. Most existing equations of bond strength and bond-slip laws ignore the heterogeneous nature of concrete, resulting in considerable disparities with experimental data. In this study, the mesoscale finite element modelling approach developed and validated previously is applied in extensive Monte Carlo simulations (MCS) of FRP-concrete bonded joints with various concrete compressive strength and coarse aggregate fractions (AF). Based on the MCS results, AF-dependent empirical equations for the bond strength and the interfacial bond-slip law are proposed and validated against 101 FRP-concrete joint tests under single-shear loading. The consideration of AF leads to closer predictions of bond strength and force-displacement curves to the test data than the widely-accepted Chen and Teng’s bond-strength model and Lu et al.’s bond-slip law.
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