Fiber volume fraction and ductility index in fiber-reinforced concrete round determined panels

Due to the high scatter affecting the post-cracking response of Fiber-Reinforced Concrete Beams (FRC-B) in bending, new Fiber-Reinforced Concrete Round Determined Panels (FRC-RDP) are tested. Accordingly, the introduction of a model to predict the flexural response of FRC-RDP is of practical interest. Similarly to FRC-B, the response of centrally loaded FRC-RDP can be described by the Ductility Index (DI), which defines the deflection-softening or the deflection-hardening behavior. Since DI is proportional to the difference between ultimate and effective cracking loads, the brittle/ductile transition corresponds to DI equal to zero. Moreover, a linear increment of DI with the amount of fibers can be theoretically and experimentally found for both beams and panels. Through this general relationship, the minimum amount of fibers for ductile response can be determined.