Numerical modelling of UHPFRC beams under impact load

The development of ultra-high performance fibre reinforced concrete (UHPFRC) has recentlyreceived extensive attention from researchers. Various applications of UHPFRC have also been explored. This research is concerned with the resistance of UHPFRC under impact and rocket propelled grenade attacks. One interesting problem for UHPFRC is that its values of flexural tensile strength in the literature can be up to 35MPa, obtained with the use of σ=My/I which assumes a linearly varying stress through the depth of the section.This equation is not applicable for UHPFRC which has a pseudo-hardening region after cracking. Therefore,the tensile stress-strain behaviour must be obtained from axial tensile tests and not flexural tests. A drop hammer test rig has been designed and fabricated to investigate the impact resistance of UHPFRC beams. The aim of the project was to quantify the improved resistance of UHPFRC under impact when compared to ordinary concrete and to investigate the possibility of accurately modelling its behaviour under both static and impact/dynamic loadings in the first instance and ultimately modelling the damage from rocket propelled grenades. A preliminary study of the project is reported in this paper.