The present work aims at investigating the structural behaviour of steel-fibrereinforced concrete (SFRC) beams under high-rate loading conditions mainly associated with impact problems. A simple, yet practical non-linear finite-element analysis (NLFEA) model was used in the study. The model is mainly focused on realistically describing the fully brittle tensile behaviour of plain concrete as well as the contribution of steel fibres to the postcracking response. The constitutive relations were incorporated into ABAQUS software brittle-cracking concrete model in order to adjust the latter to allow for the effects of fibres. Comparisons of the numerical predictions with their experimental counterparts demonstrated that the model employed herein, despite its simplicity, was capable of providing realistic predictions concerning the structural responses up to failure for different SFRC structural configurations. In the present study, the previous work is extended in order to numerically investigate the structural responses of simply-supported SFRC beams under impact loading. Data obtained from drop-weight tests on RC beams (without fibres) indicates that the response under impact loading differs significantly from that established during equivalent static testing. Essentially, there is (i) an increase in the maximum sustained load and (ii) a reduction in the portion of the beam span reacting to the impact load. However, there is considerable scatter making it difficult to ascertain the effect of loading rate on various aspects of RC structural response. To achieve this dynamic NLFEA is employed which is capable of realistically accounting for the characteristics of the problem at hand, a wave propagation problem within a highly non-linear medium. Following validation, a further study was conducted to assess the effect of steel fibers (provided at a dosage of Vf = 1%) on key aspects of structural response such as maximum sustained load, load-deflection curves, deformation profiles and ductility) under different rates and intensities of impact loading. The predictions reveal that steel fibers can potentially increase the maximum sustained load, ductility, toughness exhibited by SFRC members under impact loading compared to their RC counterparts.

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