Fatigue and Monotonic Behaviors of Corrosion-Damaged Reinforced Concrete Beams Strengthened with FRCM Composites

This paper provides a comprehensive account of using fabric-reinforced cementitious matrix (FRCM) composites to strengthen corrosion-damaged reinforced concrete (RC) structures subjected to monotonic loading and fatigue. Twelve beams were constructed and tested to failure under four-point loading configuration. Prior to testing, 10 beams were subjected to accelerated corrosion for 140 days, leading to an average mass loss in the steel reinforcement of 19%. Eight corrosion-damaged beams were strengthened and tested while the other two beams remained unstrengthened. Two other virgin beams that were not subjected to corrosion were used as benchmarks. The test parameters included the fabric material (polyparaphenylene benzobisoxazole and carbon), the number of FRCM plies, the strengthening configuration, and the type of loading (monotonic and fatigue). Test results showed that the corrosion of steel bars dramatically decreased the fatigue life of the beams. After strengthening, the corrosion-damaged beams fully restored the load-carrying capacity of the virgin beam. The FRCM-strengthened beams endured more load cycles than those endured by their unstrengthened benchmarks but could not restore the original fatigue life of the virgin beam. The effect of FRCM configuration was more pronounced in the beams subjected to fatigue than those tested monotonically. PBO-FRCM composites were more effective than the carbon counterparts in enhancing the fatigue performance of the corrosion-damaged beams.