Comparative behaviour of hollow columns confined with FRP composites

Confining columns with fibre reinforced polymer (FRP) composites have been investigated in the last few decades to address the problem of upgrading and retrofitting reinforced concrete (RC) columns; however, most studies have concentrated on solid columns. This paper investigates the comparative behaviour of FRP confined hollow RC columns subjected to concentric loading. A total of twelve RC columns made from high strength concrete (HSC) were cast and tested. Six of the columns had a circular cross section (two solid columns, two hollow columns each having a circular hole, and two hollow columns each having a square hole) and the remainder columns had a square cross section (two solid columns, two hollow columns each having a circular hole, and two hollow columns each having a square hole). Six columns in total, three from each configuration were left unconfined as control specimens, while the others were confined with FRP. It was found that FRP confinement increased hollow RC columns’ axial load and ductility capacities; and hollow columns having circular holes had better performance compared to hollow columns having square holes.