The Antifragility of FRC in the Crack Pattern of Reinforced Concrete Ties

To assess the durability of Reinforced Concrete (RC) structures, a model capable of predicting the crack pattern of RC ties is herein introduced. Based on the classical tension-stiffening equations, such model provides the transfer length, which in turn depends on the bond-slip mechanism between steel and concrete. The aim is to compute the length of a tie which shows a single crack in the serviceability stage. In this particular situation, if the geometry does not change, transfer length only depends on the strength of plain or fiber-reinforced concrete (FRC). Nevertheless, the experimental investigation, performed on RC and R/FRC ties with the same geometrical and mechanical properties, reveals two different crack patterns. Specifically, RC ties show multiple cracking, whereas only one crack tends to appear in presence of FRC. This dichotomy can be ascribed to the so-called antifragility, which can be considered as the capacity of FRC to gain strength from its intrinsic disorder.