Sectional analysis of the flexural creep of cracked fiber reinforced concrete

This paper presents a sectional analysis of cracked fiber reinforced concrete (FRC) under flexural loading. The approach considers three separate loading conditions: monotonic, cyclic, and creep bending loads. Different parts of the approach are experimentally calibrated and validated with tests on polypropylene FRC. In the monotonic regime, numerical optimization is used to find the optimal stress–strain relation of FRC to capture the experimental bending behavior as closely as possible, while satisfying the horizontal force and bending moment equilibrium. To model the cyclic behavior, the constitutive law is extended by introducing a tension-only scalar damage function. The agreement between the predicted and measured response is again very good, and the measured upwards shift of the neutral axis during unloading is predicted as well. Finally, the flexural creep response of a cracked FRC beam is simulated by using uniaxial creep data. The approach predicts the time-dependent crack widening under sustained flexural loading and can be used to check SLS criteria in the design of FRC elements.