Fatigue performance of CFRP patched pre-cracked steel plates after extreme environmental exposure

Carbon fibre reinforced polymers (CFRPs) provide new, lightweight and durable possibilities in structural rehabilitation. However, their industrial applications are limited due to lack of knowledge on the durability and effectiveness of CFRP patches under field like exposures. This paper outlines an experimental investigation into the fatigue life of CFRP sheeting patched pre-cracked steel plates under elevated temperature marine submergence. Tri-layered high modulus CFRP repaired steel systems were submerged in a 5% (by weight) NaCl solution for durations up to 6 months at 20 and 50 °C, while under a static tensile load to simulate service load. After immersion, specimens were fatigue loaded in tension at 15-150 MPa until complete failure for the purpose of the determination of the severity of degradation that aggressive environmental exposure caused to the life of CFRP to steel patches. These tests exhibited fatigue life extensions of between 1.85 and 3.26 when a single side of the crack was patched, and greater than 24 for double-sided patch configurations. The results demonstrate CFRP applications enhance the fatigue life of damaged steels and can in fact be adapted even under extreme exposure scenarios.