Experimental Investigation about the Behavior of Retrofitted Plain Concrete Columns using a Novel Hybrid Steel-FRP Confinement

In current study, a novel retrofitting scheme, hybrid confinement using steel reinforcement profiles and FRP wraps was presented for strengthening of columns and plain concrete piers and verified using the results of an experimental work results. Twenty cylindrical concrete specimens were produced in laboratory conditions and energy dissipation, axial deformation, initial stiffness and load-deflection curve was calculated for each specimen. Two of specimen was used as benchmark, however the other were retrofitted using CFRP wraps, GFRP wraps, near surface mounted steel rods, FRP confinement and proposed retrofitting scheme. Based on the results, axial compressive strength, energy dissipated and ductility was enhanced. The axial force-axial displacement behavior of hybrid confined specimens had two parts. In the first part a parabola curve was observed whereas in the second part the behavior was linear. The failure of specimens was brittle and had explosive nature towards CFRP or GFRP rupture. However the results proved that we will be able to use the proposed novel confinement scheme for shear and flexural strengthening of columns and plain concrete piers of road and railroad bridges.