Performance evaluation of high strength concrete and steel fibre high strength concrete columns reinforced with GFRP bars and helices

- Behaviour of GFRP bar reinforced HSC (GFRP-HSC) columns is investigated.
- Behaviour of GFRP bar reinforced steel fibre HSC (GFRP-SFHSC) columns is reported.
- Axial load-bending moment (P-M) interactions of GFRP-HSC columns are presented.
- Axial load-bending moment interactions of GFRP-SFHSC columns are also presented.
- Procedure of establishing analytical P-M interaction diagrams is proposed.

This study presents the results of an experimental investigation on high strength concrete (HSC) and steel fibre high strength concrete (SFHSC) circular column specimens reinforced longitudinally and transversely with Glass Fibre-Reinforced Polymer (GFRP) bars and helices, respectively. The Influence of the type of the reinforcement (steel and GFRP), the pitch of the transverse reinforcement, the addition of the steel fibres and the loading condition (concentric, eccentric and four-point loading) on the performance of the specimens was investigated. The study showed that the GFRP bar reinforced HSC (GFRP-HSC) specimen is as efficient as the steel bar reinforced HSC (steel-HSC) specimen in sustaining concentric axial load. However, the maximum load sustained by the GFRP-HSC specimens under eccentric axial load was 10-12% lower than the maximum load sustained by the steel-HSC specimens. GFRP bar reinforced SFHSC (GFRP-SFHSC) specimens sustained 3-13% higher axial load and 14-27% greater ductility than GFRP-HSC specimens under different loading conditions. Furthermore, reducing the pitch of the GFRP helices in GFRP-SFHSC specimens resulted in a significant improvement in the ductility and the post-peak axial load-axial deformation behaviour of the specimens.