Bond strength of deformed reinforcing bars in plain high-strength concrete and high-strength steel fibre-reinforced concrete

Rapid splitting bond failures associated with high strength concrete (HSC) can be prevented with the addition of a confinement mechanism such as transverse reinforcing or fibre reinforcing. Furthermore, the addition of fibers results in a reduction in bar stress since the concrete below the neutral axis is capable of carrying some tension. To date, most studies of bond behaviour in fibre reinforced concrete (FRC) have not accounted for concrete tension below the neutral axis.; In this study 16 full scale (3 meters long) spliced-beam specimens are evaluated under third point loading with bars spliced in the central zone of pure flexure. Of these specimens, 9 were cast with normal high strength concrete (HSC) and 7 were cast using high strength steel fibre reinforced concrete (HS-SFRC). The fibres used are Dramix RC-80/60-BP high tensile steel fibres for high strength concrete at a dosage of 60 kg/m3. Spliced longitudinal reinforcing bars used in this study have normal relative rib areas and are of size 15M, 20M and 25M. Minimum transverse reinforcing stirrups are provided along the splice in 5 of the plain HSC specimens and in 4 of the FRC specimens. (Abstract shortened by UMI.)...