Experimental and numerical study of compressive behavior of axially loaded circular ultra-high-performance concrete-filled tube columns

To test the compressive behavior of ultra-high-performance fiber-reinforced concrete UHPFRC columns, numerical and experimental investigations were conducted using various confinement materials under axial compression loading. A total of seven columns were examined in the current experimental work. In this study, the major variables included the utilization of an outer steel tube, an inner steel tube, an outer polyvinyl chloride (PVC) tube, and an external wrap by CFRP, i.e., carbon fiber- reinforced polymer wrap. For UHPFRC-filled tube columns, a 3D finite element (FE) simulation has been developed. The commercial FE program ABAQUS was used. Moreover, validation against the obtained experimental results was carried out. The results showed that the outer steel tube had a better confinement impact on the given core concrete compared with the PVC tube and the CFRP sheet. The axial capacity of the column specimens confined with steel, PVC and CFRP was enhanced about 53 %, 13 %, 27 % compared to control specimens. All proposed confinement schemes improved the columns’ ductility and energy absorption considerably. Furthermore, the simulation results confirmed the reasonableness of the FE model of specimens to a significant extent; thus, they can be reliable to produce more predictions.