Pull-out bond efficiency and load capacity of the bonded HSC strips reinforced with steel and FRP bars to concrete

This study used the pull-out test to study the efficiency of bonding reinforced concrete (RC) strips to the concrete elements. The effect of width, thickness, bond length (Lb), and reinforcing materials (steel and Glass fiber reinforced polymer (GFRP)) of the bonded reinforced high-strength concrete (RHSC) strips was experimentally investigated. Moreover, a 3D finite element (FE) model constructed using the ABAQUS program was verified by comparing the model and the experimental results. The geometry and materials' nonlinearity were considered in the FE model to precisely predict the behaviour of the experimentally tested specimens. Subsequently, a detailed parametric study was planned and conducted using the verified FE model to study the effect of additional test variables. The experimental and FE results confirmed that increasing the bond length and width of the RHSC strip generally increased the specimen failure load. Moreover, increasing the Lb from 150 to 300 mm was slightly more effective than increasing the strip width from 30 mm to 40 mm. Increasing the Lb for steel from 150 to 300 mm, the pull-out load at failure (Pu,Exp.) increased by 56.1, 68.2, and 67.1 % for the specimens of RHSC strips width of 30, 40, and 50 mm, respectively. For GFRP specimens, increasing Lb from 150 to 300 mm, the P u,Exp. increased by 20.6, 25.6, and 22.0% for the specimens of RHSC strips widths of 30, 40, and 50 mm, respectively. It is recommended to study the effect of loading conditions, epoxy, and materials of both the concrete layer and reinforcing bars on this strengthening system.