Environmental durability of FRP to steel bonded joints in bridges

Over the past four decades, fiber reinforced polymers (FRP) have been increasingly used for strengthening, repair and refurbishment of bridges. Although, the short-term behavior of FRP/steel bonded joints has been extensively studied, the subject of the durability has not been researched to the same degree. The lack of knowledge regarding the long-term performance presents a major obstacle to the growing application of FRPs in bridges. This work aims to investigate the effects of temperature, de-icing salt solutions and moisture on mechanical behavior of Carbon-FRP/steel joints. To realize this aim, forty CFRP/steel double lap shear specimens were aged in simulated de-icing salt solution and deionized water at 20\ub0C and 45\ub0C for up to eighteen months. The test results indicate a clear change of failure mode from cohesive to interfacial or interlaminar failure. Even though all the joints exhibited increasing load-bearing capacity during the first six months, the failure load of specimens aged at higher temperatures started to decline afterwards