Experimental Evaluation of CFRP-Concrete Bond Behavior under High Loading Rates Using Particle Image Velocimetry Method

Abstract

Numerous studies have been conducted to evaluate bond behavior between fiber-reinforced polymer (FRP) composites and concrete substrate in externally bonded reinforcement (EBR) systems subject to static loads. However, few investigations examined the bond behavior under dynamic loads, and in particular under high loading rates. This study investigates FRP-concrete bond behavior under quasi-static and high loading rates. For this purpose, 12 concrete prisms were strengthened with carbon FRP (CFRP) sheets and subjected to the single-shear test under different loading rates. The particle image velocimetry (PIV) method is used as an image processing technique to obtain the deformation and strain fields. Results indicate that bond capacity rises with increasing loading rate, which is more considerable in the case of low-strength concrete specimens. The increased bond capacity is attributed to the different mechanisms of bond fracturing under quasi-static and high loading rates. This motivates a thorough evaluation of the effects of the relevant mechanisms on bond behavior. Bond analysis by means of the PIV method reveals not only an increasing interfacial shear stress distribution between the CFRP composite and the concrete substrate, but also concentration of strain on the CFRP sheet. Finally, bond-slip graphs are used to show that the high loading rates applied increase the specific fracture energy.