Post-Fire Behavior and Repair of Fire-Damaged RC Columns Using Composite Jackets

Reinforced concrete (RC) structures are frequently employed in construction owing to their versatility, strength, and durability. However, these structures can be vulnerable to fire incidents, which can significantly compromise their structural integrity and load carrying capacity. In the aftermath of a fire, damaged RC columns often necessitate rehabilitation to restore their strength and functionality. The present study intends to carry out a numerical investigation of the behavior of reinforced concrete (RC) columns after their exposure to fire. As a first step, the study examined the effects of exposing the columns to fire for different periods (15, 30, 60 and 90 minutes) on the column's residual load-bearing capacity by considering some decisive geometrical parameters such as the column height and its cross-sectional area. The second step consisted of investigating the effectiveness of the strengthening techniques utilized by adding reinforcement and incorporating composite jackets, where each method used three external concrete compressive strength values, 25, 30, and 40 MPa, in order to improve the post-fire behavior of these columns. The results showed that the longer the column is exposed to fire, the lower its bearing capacity. However, it was also found that increasing the column cross-sectional area can reduce the percentage of load-bearing capacity. Moreover, A simple equation with sufficient accuracy has been proposed to predict the bearing capacity of reinforced columns. Finally, it was revealed that the strengthening methods used herein allowed restoring the capacity of the columns exposed to fire, but the strengthening technique using a composite jacket with steel plates showed better results in terms of strength. Where this technique allowed, it restored the capacity of the columns exposed to fire for a period of one hour by up to 182%.