Effects of novel multiple hooked-end steel fibres on flexural tensile behaviour of notched concrete beams with various strength grades

3-point bending tests were carried out on notched low, normal and high strength concrete beams containing single or novel multiple hooked-end steel fibres, ranging 0 similar to 110 kg/m(3) in dosage, 35 similar to 60 mm in length, and 0.55 similar to 0.90 mm in diameter. The experimental results suggest that the Limit of Proportionality (LOP), which is related to initial concrete cracking, largely depends on concrete strength rather than fibre properties. Increasing fibre dosage, length, aspect ratio and number of hooked-end are beneficial for enhancing residual flexural tensile strength of steel fibre reinforced concrete (SFRC). New empirical equations, which can explicitly characterise the effects of concrete strength and fibre properties, were proposed to predict the LOP and residual flexural tensile strength of SFRC. By using the proposed equations, the effects of concrete strength and fibre properties on LOP and residual flexural tensile strength were discussed in depth. It was concluded that the LOP is mainly governed by concrete strength, while the residual flexural tensile strength is mainly dictated by fibre properties.