Numerical simulation of bonding performance between GFRP and lightweight aggregate concrete

Abstract This study investigates the bonding performance between Glass Fiber-Reinforced polymer (GFRP) bars and Lightweight Aggregate Concrete (LWAC). We established 81 central pull-out numerical simulation scenarios to analyze the influence of four factors—lightweight aggregate concrete strength grade, GFRP bar diameters, GFRP bar rib height, and GFRP bar bonding length—on the bonding performance between LWAC and GFRP bars. The results indicated that considering the surface characteristics of GFRP and the intrinsic model of LWAC, the bonding damage pattern between GFRP and LWAC can be accurately reflected. The damage patterns observed in the simulations were generally consistent with experimental findings. The ultimate bond strength between GFRP and concrete increased with the increase in LWAC strength. However, beyond a concrete strength of 50 MPa, the enhancement in ultimate bond strength becomes marginal. Within a certain range, the ultimate bond strength decreases with increasing GFRP diameter and bond length, while it increases with increasing GFRP rib height. The predictions from our GFRP and LWAC bonding strength model closely matched the experimental values, with prediction errors within 15%. The numerical simulation method and the ultimate bond strength prediction model established in this paper provide scientific reference and theoretical support for the evaluation of the bonding performance between lightweight aggregate concrete and GFRP bars.