Compressive performance of SFCB-reinforced and FRP-confined concrete cylinders

This paper presents an experimental and analytical investigation on the compressive performance of concrete cylinders internally reinforced with steel -fiber -reinforced composite bars (SFCBs) and externally confined with fiber -reinforced polymer (FRP) sheets, termed herein as S -F -RC cylinders. Eleven concrete cylinders, with different confinement conditions and with (or without) longitudinal SFCBs, were tested under monotonic compression. Two distinguishable failure mechanisms, global buckling and local buckling, were discovered for SFCBs in S -F -RC cylinders, under weak and strong confinement conditions, respectively. The S -F -RC cylinders exhibited a marked increase in failure strain of the confinement, directly translating to an enhanced compressive failure strain for the longitudinal SFCBs under strong confinement conditions. Existing models for FRP-reinforced concrete cylinders were found to underestimate the load -carrying capacity of S -F -RC cylinders. An existing compressive stress -strain model for SFCB was extended to the case of S -F -RC cylinders. The proposed method offers accurate predictions, effectively mitigating the discrepancies caused by varying confinement and material properties across different SFCBs.