Behavior of Concrete-Filled Hybrid Large Rupture Strain FRP Tubes Under Cyclic Axial Compression

This paper experimentally investigates the behavior of concrete filled fiber reinforced polymer (FRP) cylinders under cyclic axial compression. The FRP used in this study were either Glass FRP or hybrid Large Rupture Strain (LRS-FRP) and conventional Glass FRP (GFRP). LRS-FRP are manufactured out of polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) obtained from recycled plastics. Hence, they are much cheaper and environment-friendly than conventional GFRP or carbon FRP (CFRP). LRS-FRP has high tensile rupture strain (usually greater than 5%) compared to 1-2% for GFRP and CFRP. This study presents the results of a total of 5 specimens having different confinement ratios to investigate the behavior of concrete filled LRS-FRP or hybrid LRS-FRP and GFRP tubes in terms of ductility, ultimate strain, and strength improvement. The results showed that using LRS-FRP significantly improved the ductility of the confined concrete. However, the improvement in strength was limited. The hybrid confinement improves both the ductility and strength.