Shear strengthening of corroded reinforced concrete columns using pet fiber based composties

Polyethylene terephthalate (PET) fiber-reinforced polymer (FRP) composites are characterized by a large rupture strain (LRS) (usually larger than 5%) but a low elastic modulus compared to conventional FRP materials made of carbon, glass, and aramid fibers. Previous studies have proved that the use of PET FRP sheets as jacketing materials for plain concrete or reinforced concrete (RC) columns could efficiently enhance their ductility. This paper presents a combined experimental and analytical study on the shear strengthening of corroded RC columns with stirrups having different levels of corrosion before strengthening. The shear resistance contributions from the substrate column and PET FRP sheets at various volume ratios were carefully examined and their interaction mechanisms were discussed. Design equations following a conventional truss analogy were then proposed to predict the shear strength of PET FRP-wrapped columns considering the effect of stirrup corrosion, and the predictions were verified against the test results.