Numerical Modelling of Fiber-Reinforced Concrete Shear-Critical Beams

The numerical modelling of shear-critical reinforced concrete beam has been a traditional challenging problem due to the varying mechanisms involving the shearing problem. The inclusion of fibres improves significantly the shear strength of the beams but include in the equation a new unknown. In this study, a group of 16 beams with varying parameters including steel or macro-synthetic fibres, presence or not of transverse reinforcement, different shear-span-to-depth ratios, and different transverse reinforcement ratios are studied. The numerical modelling makes use of the nonlinear finite element analysis following the smeared crack approach and a total strain based crack material model. The numerical modelling has shown that a nonlinear finite element model can predict with great accuracy the behaviour and the strength in those beams with presence of transverse reinforcement. For the case of members without transverse reinforcement, the predictions of the shear strength are acceptable but some doubts remain unclear since these beams are characterized by a failure originated in a major critical crack. A parametric analysis based on the crack bands employed is discussed to give recommendations for a good numerical modelling of FRC shear-critical beams.