AXIAL COMPRESSION TESTS ON LARGE-SCALE FRP-CONFINED RC COLUMNS

To enable the safe and reliable design of confining FRP jackets for the strengthening of RC columns, the stress strain behaviour of FRP-confmed concrete needs to be properly understood and modelled. While numerous studies have been conducted on FRP-confined concrete using small-scale FRP-confmed plain concrete specimens, uncertainties and concerns exist with regard to the direct extrapolation of conclusions reached in these studies to the behaviour of FRP-confined concrete in large-scale reinforced concrete (RC) columns on which there has been very limited work. Against this background, this paper presents the test results of part of an ongoing experimental programme on large-scale FRP-confined RC columns. The entire experimental programme comprising 16 axial compression tests on large-scale RC columns is first descried. Details of the four tests already completed are then reported and the results discussed. These results confirm the expected benefits of FRP confinement of RC columns in enhancing both their strength and ductility. As with small-scale plain concrete specimens, the hoop rupture strain of an FRP jacket in a large-scale RC column is much lower than the material ultimate tensile strain from flat coupon tests; this reduction appears to be more severe in large RC columns than in small plain concrete specimens. The completed tests have also shown that the instrumentation scheme needs to be refined in future tests to better capture the development of strains in the FRP jacket.