Effect of steel fibres on concrete at different temperatures in terms of shear failure

The behaviour of concrete reinforced with steel fibres at elevated temperatures was investigated in terms of shear deterioration. Using three different steel fibre contents (0, 40 and 80 kg/m³), 45 push-off specimens were tested at five maximum temperatures (20, 150, 300, 500 and 700°C). The main objective of the research was to investigate the effect of steel fibres on the behaviour of concrete at different maximum temperatures in terms of shear failure. The results revealed enhanced ductility and shear strength at elevated temperatures. In addition, the crack widths and crack slips were measured using linear variable differential transducers. It was found that the use of steel fibres increased the shear strength of the concrete at ambient temperature by 103% and 102% for steel fibre contents of 40 and 80 kg/m³, respectively. Although this enhancement was reduced at the high temperatures (500 and 700°C), the mixes containing fibres still had higher residual shear strengths than the plain concrete mix. The steel fibre content also affected the ductility at both ambient and high temperatures.