Few studies are available on members reinforced internally with fiber-reinforced
polymer (FRP) bars and subjected to compressive axial load; therefore, the behavior of FRP
internally reinforced concrete columns has not been well established. In this paper,
experimental results of 23 nearly full-scale square concrete columns reinforced transversally
with glass FRP (GFRP) and carbon FRP (CFRP) ties, and longitudinally with GFRP, CFRP,
and steel bars, and subjected to concentric monotonic axial compression