Actions for Verification of RC Structures with FRP Bars

The use of concrete reinforced with nonmetallic bars in composite materials, characterized by higher values of strength and by lower values of Young's modulus compared to steel, implies that the design of structures will be influenced almost exclusively by the serviceability limit state (SLS). This circumstance deserves some reflection on the values of the actions to be considered at the SLS and at the ultimate limit state (ULS). As the actual codes consider the same distribution of actions obtained by statistical methods, for the SLS and, amplified, for the ULS, it is necessary to reexamine from a probabilistic point of view the effective distributions of actions to be adopted for the two different limit states. This, which is obviously true for any kind of structure built with any material, becomes paramount for concrete structures with nonmetallic reinforcement. In this paper some possible statistical distributions of actions for the verification at the ULS and the statistical distribution of the sampled values, to be correctly used for the SLS verifications, are evaluated.