This paper presents the results of the first-ever experimental study on the axial compressive behavior of
steel fiber reinforced high-strength concrete (SFRHSC)-filled FRP tubes. A total of 27 circular unreinforced
and steel fiber reinforced high-strength concrete FRP tubes (SFRHSCFFTs) were tested under axial compression.
The effects of steel fiber parameters, including fiber shape, fiber aspect ratio and fiber volume
fraction were examined. Concrete type was also investigated as a parameter, where two different types of
concrete, including a conventional HSC and slurry infiltrated fiber concrete (SIFCON) were considered.
The results indicate that both SFRHSCFFTs and SIFCON-filled FRP tubes (SIFCONFFTs) exhibit highly ductile
compressive behavior. The results also indicate that the axial stress–strain behavior of CFFTs is influenced
by the presence and amount of internal steel fibers, with particularly significant influences noted
on the FRP hoop rupture strains and post-peak strength losses. It is found that fiber volume fraction significantly
affects the compressive behavior of CFFTs. Concrete type, fiber shape and fiber aspect ratio also
have some, but less significant, influence on the behavior of CFFTs. It is observed that the compressive
strength and ultimate strain of CFFTs increases with an increase in fiber volume fraction or a decrease
in fiber aspect ratio. It is also observed that CFFTs reinforced with hooked end steel fibers exhibit
improved compressive behavior compared to the companion CFFTs reinforced with crimped fibers.