Static bearing capacity of partially corrosion-damaged reinforced concrete structures strengthened with PET FRP composites

Abstract

Abstract This study evaluated the static bearing performance of partially corrosion-damaged reinforced concrete (RC) beams and columns strengthened with polyethylene terephthalate (PET) composites. According to the electrochemical corrosion method, the corrosion rate of reinforcements in the key regions of columns and beams were designed as 15%, which conformed to the actual situations of the non-uniformly corroded steel bars in the RC structures. After that, the partially corroded RC columns and beams were strengthened with PET composites. Specimens strengthened with carbon fiber reinforced plastic (CFRP) and without strengthening worked as the control groups. SEM studies showed that the good interface bonding performance between PET and concrete ensured the excellent integrity of PET-strengthened structures. Experimental results showed that the ductility and bearing capacity of columns and beams got greatly decreased due to the corrosion of reinforcements, and PET composites could effectively repair the damagement caused by corroded steel bars. The ductility improvement by PET composites was better than that of CFRP. For axial compression, the ductility index of CP-0 column improved by 334.62% compared to that of CF-0 column. Similar to the corroded RC columns, the ductility index of CP-15 column improved by 127.49% than that of CF-15 column. A calculated model was proposed to predicate the stress–strain relationship of PET composites strengthened partially corroded RC columns accurately. For flexure, PET and CFRP composites strengthened beams had the same ultimate bearing capacity. Meanwhile, PET composites could better ensure the ductility of partially corroded RC beams than that of CFRP. Compared to BF-0 beam, the ductility index of BP-0 beam increased by 93.75%. Compared to BF-15 beam, the ductility index of BP-15 increased by 69.23%. In the compression and flexure tests, the rupture strain of PET composites improved by 114.82%∼164.11% than that of CFRP, which took full advantage of the high deformation property of PET composites. The study therefore concludes that PET composites is a suitable material for external strengthening of partially corroded RC structures.