Experimental Study on Bond Behavior between CFRP Plates and Steel Substrates Using Digital Image Correlation

Abstract

© 2016 American Society of Civil Engineers. The bond between carbon-fiber-reinforced polymer (CFRP) and steel is crucial for strengthening of steel structures using CFRP materials. However, existing studies on this issue are still limited. To better understand the bond behavior of CFRP-to-steel bonded interfaces, this paper reports an experimental study on the behavior of CFRP plate-to-steel bonded joints with a nonlinear adhesive by the single-shear testing method. The three-dimensional digital image correlation (3D-DIC) technique was used to measure the displacements and strains of the specimens. The effects of the bond length and adhesive thickness on the bond behavior are evaluated. The results show that failure occurred within the adhesive layer (i.e., cohesive failure) for all tested specimens. The ultimate load increased with increasing bond length until the effective bond length was reached. The ultimate load also increased as the adhesive thickness was increased from 0.5 to 2.0 mm. The bond-slip relationship exhibited an approximate trapezoidal shape for such bonded joints. The key parameters of the trapezoidal bond-slip relationship were obtained for specimens with different adhesive thicknesses. This study indicates that the 3D-DIC technique is suitable for application in studies of the interfacial behavior between CFRP plate and steel.