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Fiber reinforced polymer confined rc circularcolumns subjected to axial load and bending moment

Doruk, Koray
Fiber reinforced polymers (FRPs) have gained increasing popularity in upgrades of reinforced structural elements due to high strength to weight ratio and ease of application. In this study, the effectiveness of the carbon reinforced polymer wrapping (CFRP) on ductility and strength of circular reinforced concrete columns, made of low strength concrete, is presented. Four circular reinforced columns with similar dimensions, longitudinal and confining steel reinforcement were tested under combined axial load and bending moment. Three specimens were strengthened with CFRP and the results were compared with the control specimen. The main parameter of the experimental study was selected as the level of eccentricity. First of all, the strain profiles of FRPs in the circumferential direction were observed and the confining stress distributions were examined. Then, an axial stress-strain model for FRP confined concrete with a transition from softening to hardening response for different confinement ratios is proposed. The proposed model was verified by comparing the model estimations with the test results obtained from this study and results reported by other researches. In addition, a parametric study was presented to obtain a simple equation to estimate curvature ductility of FRP confined circular columns.