Short-term bond behavior and debonding capacity of prestressed CFRP composites to steel substrate

In this study, the short-term bonding behaviors of prestressed CFRP plates to steel substrates and their debonding capacities have been investigated. For this purpose, single lap-shear and prestress release tests were performed on adhesively bonded CFRP-to-steel joints. The feasibility of accelerated curing (AC) of the adhesive by heating was also investigated based on the conducted tests. Moreover, bond tests with partial prestress release and subsequent lap-shear loading were conducted to examine the feasibility of prestressed strengthening of steel members using AC. A three-dimensional (3D) digital image correlation (DIC) technique was utilized to monitor the bond behavior of CFRP-to-steel joints. Experimental results demonstrated that a mixed-mode I/II (tensile/shear) fracture governs the debonding failure of CFRP-to-steel joints during the prestress release. However, given that the steel substrate cannot undergo tensile failure, a relatively high prestressing force can be transferred to the steel substrate prior to debonding. The experimental results also revealed that the AC of the epoxy adhesive can be an advantageous alternative to the conventional room temperature curing (RTC) for strengthening steel members with prestressed bonded CFRP plates.