Comparative study of different strengthening methods on the RC columns exposed to high temperatures

Fire incidents wreak havoc on the stability of structures. When structural members are exposed to high temperatures, the integrity and lifespan of the whole structure come under investigation. If the damage is repairable, strengthening techniques are suggested. Thus, this investigation focuses on the efficiency of three different confinement-strengthening schemes: High Strength Fiber Reinforced Concrete (HSFRC), Ferrocement, and Glass Fiber Reinforced Polymer (GFRP) jacketing. The critical parameters examined here were the specimens’ shape (circular and square cross-section), various heating regimes, and the schemes used for strengthening. Under the experimental program, the strengthened specimens were subjected to monotonic loading up to ultimate axial strength. The specimens damaged by heat demonstrated a significantly greater reduction in stiffness when contrasted with the decrease noted in the ultimate load. Nevertheless, the strength of samples reinforced with GFRP jackets was notably greater than that of the heat-damaged unstrengthened specimen and the specimen without exposure to heat. Meanwhile the square samples strengthened with GFRP and heated to 900 °C could not regain their original strength. Also, strengthening the samples with FC and HSFRC jacketing showed better results in rejuvenating the stiffness of the heat-damaged samples. Overall, among all the tested strengthening schemes, GFRP jacketing proved to be an efficient technique for strengthening damaged columns.