Tension stiffening of RC Ties Strengthened with externally bonded FRP Sheets

Externally bonded laminates of fiber reinforced polymers (FRPs) are becoming more and more common for rehabilitation and strengthening of RC structures, to solve problems either in serviceability or at ultimate conditions. This paper focuses on the behavior in the serviceability state: in particular, verifications in terms of cracks widths and crack spacing, used to warrant the functionality of FRP-RC structures, are considered. Test results on RC ties externally reinforced with FRP laminate are reported and the applicability of the Eurocode2 formulation used for RC elements is discussed. Provisions given by the International Federation for Structural Concrete are also analyzed.