Experimental investigation of pre‐damaged circular RC columns strengthened with fabric‐reinforced cementitious matrix (FRCM).

This paper aims at investigating the efficiency of strengthening pre‐damaged circular reinforced concrete (RC) columns with Polyparaphenylene Benzobisoxazole fabric‐reinforced cementitious matrix (PBO‐FRCM). The investigated parameters were the degree of pre‐damage (non‐damaged, damaged monotonically up to yielding, or fatigue damaged), the number of PBO‐FRCM layers (0, 2, or 4), and the tie spacing (180 or 90 mm). The experimental results of testing 12 short columns under axial compression showed that PBO‐FRCM systems enhanced the capacity of the non‐damaged columns and successfully restored and further enhanced the capacity of the pre‐damaged columns. Columns strengthened with two and four PBO‐FRCM layers showed a gain in the capacity of up to 40% and 75%, respectively. Furthermore, PBO‐FRCM wrapping enhanced the ductility of both the non‐damaged and the pre‐damaged columns, in which ductility improvement was more noticeable in columns with the larger tie spacing. Finally, the theoretical load‐carrying capacity calculated using ACI 549 provisions showed a good agreement with the experimental capacity of all tested columns. [ABSTRACT FROM AUTHOR]