Parametric Study of the Use of Strain Softening/Hardening FRC for RC Elements Failing in Bending

Using a design-oriented model recently developed for prediction of the moment-curvature relationship of a cross section of beams made by strain-softening or strain-hardening fiber reinforced concrete (FRC) and that can also include a certain percentage of longitudinal steel bars, a parametric study is carried out to evidence the effect of relevant characteristics of the post-cracking behavior of these materials in the moment-curvature and force-deflection responses of this type of structural elements. The study also analyzes the influence of the reinforcement ratio of longitudinal steel bars, ρ, in order to show that for a certain content of fibers the benefits of fiber reinforcement, mainly at serviceability limit state conditions, decrease with the increase of ρ. Adopting the formulation of the CEB-FIB final draft Model Code, the moment-crack width relationship of FRC beams reinforced with steel bars are obtained and the predictive performance of this approach is assessed by comparing analytical and experimental results.