| Circumferential wrapping of Fibre Reinforced Polymer (FRP) is one of the most common applications for the repair and rehabilitation of concrete columns. Common types of fibres used for wrapping are Carbon FRP (CFRP), Glass FRP (GFRP), and Aramid FRP (AFRP). Recently, Steel FRP (SFRP) has been introduced as a new class of composites for strengthening applications. Based on the author's knowledge, there is no experimental data available in the literature on the behaviour of large-scale columns strengthened with SFRP sheets. Thus, the main aim of this research is to investigate the effectiveness of the newly developed SFRP sheets over the conventionally used CFRP sheets. The study presented herein investigates experimentally and analytically the axial performance of CFRP and SFRP wrapped specimens.;The experimental investigation involves testing of 36 specimens to failure under monotonic axial concentric compression load. The tests were performed to examine the effectiveness of the CFRP and the SFRP sheets, the provision of adding longitudinal sheets, effects of freeze-thaw environmental exposure, slenderness effects and size effects. Detailed discussion of the stress-strain behaviour, ultimate axial strength, ultimate axial strain, ultimate hoop strain, dilation response, ductility, and the strain efficiency of the CFRP and the SFRP wrapped specimens are presented. This research also presents the first ever in-sight of the strain variation of circular specimens wrapped with SFRP sheets using Digital Image Correlation Technique (DICT). The DICT is a photogrammetric technique that allows capturing the strains from the surface of CFRP and SFRP confined concrete. The analytical investigation involves determining the accuracy of three major design code/guidelines models and five confinement models available in the literature to predict the ultimate axial strength and strain of the CFRP and the SFRP wrapped specimens. In addition, a cost effectiveness study of the CFRP and the SFRP wrapped concrete columns is also included.;Overall, it is demonstrated that wrapping the circular specimens with SFRP sheets was very effective in enhancing the performance of the concrete. Although the SFRP sheets suffered minor deterioration as a result of the freeze-thaw exposure, the strength and ductility performance of the SFRP wrapped specimens were always found to be superior to the specimens wrapped with CFRP sheets. In addition, the analytical investigation showed that all the confinement models available in the codes/guidelines and the literature have to be modified to accurately predict the stress-strain behaviour of SFRP confined concrete. Furthermore, the cost effectiveness investigation study revealed that the SFRP sheets are more effective than the CFRP sheets in terms of strength enhancement. |
