Fiber Reinforced Concrete for repairing and strengthening RC structures: some recent advancements

Enhancement of seismic behaviour of existing structures, both masonry or reinforced concrete, is a key issue for future technical activities in many Western Countries, since construction of new buildings has decreased in favour of an increased attention to the structural rehabilitation and re-use of existing buildings. The development of innovative repairing, strengthening, and retrofitting techniques is, therefore, a crucial topic to improve the structural safety of existent constructions. Fibre Reinforced Concrete (FRC) may now be particularly efficient in these cases, due to the high toughness provided by fibres that may reduce or avoid the use of conventional reinforcement.This paper presents the results of two experimental research studies carried out at the University of Brescia, concerning the use of FRC as the principal reinforcing material. The first study aims at assessing the structural response, under cyclic horizontal loads, of a full scale (1:1) Unreinforced Masonry (URM) building retrofitted with Steel Fibre Reinforced Mortar (SFRM) as external plaster. The second study concerns the seismic retrofitting of a scaled (1:4) reinforced concrete bridge pier by means of a High Performance Fibre Reinforced Concrete (HPFRC) jacketing. In both cases, repair material is applied in thin layers, due to the high mechanical properties compared to those of the respective substrates, with the addition of a limited amount of traditional reinforcement, placed only on the most stressed sections.