Stress and Strain Behavior of Slender Concrete Columns Retrofitted with CFRP Composites

This article presents the results of experimental studies about axial stress—strain behavior of retrofitted slender concrete columns with CFRP composites. In this study, 30 unreinforced concrete cylinders 100 mm diameter with variable height of 200, 400, 600, 800, and 1000 mm were prepared and retrofitted. In each group, a plain specimen (unwrapped) and five wrapped specimens with different fiber orientations (0, 0/0, 90/0, 45, and 45/0) were tested under compressive axial force up to failure. At the end, analytical models were proposed for ultimate strength and ultimate strain of the slender specimens. The results have shown that the CFRP composites are most effective in increasing the strength and ductility of slender columns.