Time-dependent behaviour of CFRP-strengthened reinforced concrete beams

Nowadays the strengthening of reinforced concrete structures with steel plate bonding techniques are being replaced by Fiber Reinforced Polymer (FRP) laminates. A lot of studies focused on short-term and static behaviour of FRP-strengthened concrete elements but only a few on long-term responses. The aim of this paper is to compare two strengthening methods: the CFRP strip bonding technique and Near Surface Mounted reinforcement (NSM CFRP). It presents results of experiments performed on five bonding concrete beams, under sustained load. The first beam was not strengthened, two of them were strengthened at the beginning of the experiment and the rest were pre-cracked before being strengthened. The results confirmed that time dependent behaviours are different when beams are strengthened by CFRP strips or NSM CFRP. It was shown that CFRP reinforcement has a positive influence on the long term behaviour of strengthened beams.