Experimental investigation of CFRP confined hollow core Reactive Powder Concrete columns

This paper presents an experimental investigation on the behaviour of hollow core Reactive Powder Concrete (HCRPC) columns confined with a circular Carbon-Fibre-Reinforced polymer (CFRP) tube. Sixteen circular hollow core specimens (206 mm in diameter, 800 mm in height and a 90 mm circular hole) were made with Reactive Powder Concrete (RPC) of 105 MPa compressive strength. These specimens were divided into four groups. The first group was the control group that consisted of four unconfined HCRPC specimens reinforced with conventional longitudinal steel bars and steel helices. The specimens of the second group had the same configuration as the first group except that these specimens were externally confined with CFRP tube. The specimens of the third group were externally confined with a CFRP tube and internally confined with a Polyvinyl chloride (PVC) tube. Finally, the specimens of the fourth group had no steel reinforcement and were only made with an external CFRP tube and an internal steel tube. These specimens were subjected to different loading conditions: concentric, eccentric (25 mm and 50 mm) and four-point bending. It was found that the CFRP tube confinement slightly increased the strength of the HCRPC columns, whereas the ductility was significantly enhanced. In addition, by introducing the PVC tube as internal confinement to the hollow columns the ductility was also improved.