Constitutive behaviour of confined hybrid fibre reinforced HPC under uniaxial compression

An attempt has been made to investigate the effect of hybrid fibres on the compressive constitutive behaviour of high-performance concrete (HPC). A total of 96 cylindrical specimens of size 150 mm × 300 mm were cast and tested under monotonic axial compression until failure. The main variables considered were the volume fraction of crimped steel fibres, the volume fraction of polypropylene fibres and the volumetric ratio of confinement. The results indicate that the strength and strain at peak load of HPC can be significantly improved by the addition of hybrid fibres as well as by increasing the volumetric ratio of confinement. Hybrid fibres can replace the confinement to some extent, by which the congestion of reinforcement can be avoided. A simple analytical model is proposed to predict the stress–strain behaviour of hybrid fibre reinforced HPC and the model was found to compare satisfactorily with experimental curves.