The fibre shear supplement of precast beam-half joints using steel fibre self-compacting concrete

Abstract

The end region of the dapped-end beam experienced multiaxial stress actions, which requires high amounts of reinforcement and this resulted to the closely space reinforcement. Therefore, hooked-end steel fibres were mixed into all beam specimens to partly replace the secondary shear and bursting reinforcement to reduce the congestion issue. A series of experiments were performed on shallow recess (SR) and deep recess (DR) half joint beams to examine the partial reduction of reinforcement with 1% replacement of steel fibre. All SR and DR beams were then tested under shear load to study the effectiveness of steel fibres over traditional reinforcement in resisting loads, with two different shear span-to-depth ratios, which are 1.4 and 2.1. The experimental shear strength fibre supplement results for the SR and DR beam specimens were compared with theoretical predictions using the analytical and RILEM methods. The incorporation of 1% of steel fibre in the concrete matrix has the ability to replace 50% of horizontal and vertical reinforcement in SR and DR beams. In general, it is found that both the analytical and RILEM methods give a close approximation for the experimental DR beam specimen values, but slightly overestimated the fibre shear supplement of SR beam specimens by 13.4%. The results support the ability of steel fibres to resist tensile stress through its fibre-bridging action.