Effect of impact velocity on the failure modes of a RC beam

•Effect of impact velocity on the failure modes of a RC beam has been studied.•Numerical results agree with test data for load-displacement curve and crack pattern.•An analytical equation to predict the transition of failure modes in a RC beam.•Different DIFs of rebar steels and concrete are the cause for failure mode change. It has been experimentally observed that the failure mode of RC beams can change from bending to shear as impact velocity increases. In this note, the effect of impact velocity on the response and failure of a RC beam is studied numerically using a recently developed dynamic constitutive model for concrete. Furthermore, an analytical equation is proposed to define critical condition for the transition of failure modes in the RC beam subjected to impact loading. It transpires that the numerical results are in good agreement with the experimental observations in terms of load-displacement curve, crack pattern and transition of failure mode. It also transpires that the analytical equation can predict the transition of failure mode in the RC beam and that different strain rate sensitivities (namely, dynamic increase factors or DIFs) of rebar steels (bending and shear reinforcements) and concrete are responsible for the transition of failure modes in RC beams from bending to shear as impact velocity increases.