Strain-rate effect on the bond strength of external bonded reinforced carbon fiber-reinforced polymer for concrete structure

This study aimed to investigate the dynamic loading strength of an external bonded fiber-reinforced polymers (FRP) system under seismic loading. Herein, 16 bonded FRP strengthening test samples under four loading speeds ranging as 0.0000167–0.8 m /s was were examined to determine the mechanical characteristics of the FRP bond strength on the concrete substrate. The mechanical tests involved measuring the concrete/FRP shear properties using a double-lap shear test. Sixteen concrete specimens were cast, strengthened using externally bonded carbon fiber-reinforced polymer sheets after FRP cutting and surface preparation, instrumented, and driven to failure in the LMC² laboratory and the BAM laboratory (Germany) at room temperature. Dynamic loading increased the bonded strength mainly because of an increase in the concrete tensile strength, which improved the bond capacity. The experimental data are then analyzed and competed with the equation given by the new European standard that develop the design of external bonded FRP (Eurocode 2 Annex J). The characteristics properties and bonded strength obtained by design equation were compared. Based on the results design equation are modified. Consequently, a relationship was proposed to consider the dynamic concrete strength according to Model Code 90. A model for calculating shear strength was proposed for seismic dynamic loading. • Concrete/FRP interface strength. • Dynamic loading. • Reinforced concrete structures. • Model. • Design bond strength.