Strengthening of structures with Steel Reinforced Polymers: A state-of-the-art review

Steel Reinforced Polymer (SRP) is an innovative system for the external strengthening of structures, which comprises unidirectional textiles of High Tensile Strength Steel applied with polymeric resin. The first applications of SRP in civil engineering date back to 2004, and, since then, a number of studies have been carried out on both mechanical characterization and structural applications. Nevertheless, the existing knowledge has mostly remained a fragmented skillset of the scientific community and specific guidelines for qualification and design have not been developed yet. This paper reviews the experimental works on SRP to establish its advantages and drawbacks and promote a proper knowledge transfer from academia to engineering design practice. With respect to the already well-established Fibre Reinforced Polymers (FRPs) with carbon or glass textiles, SRP exhibits comparable, or even better, tensile and bond behaviour, and, when applied for bending reinforcement or for confinement, provides equivalent or higher improvement of structural performance in terms of load bearing and displacement capacity. Even if long-term durability, shear strengthening of reinforced concrete beams and applications to masonry would still deserve more investigations, the research performed so far has already demonstrated that SRP is an effective and cost efficient solution for the rehabilitation of structures and that it can be reliably designed with the same relationships developed for FRPs.