Axial impact behavior of Large-Rupture-Strain (LRS) fiber reinforced polymer (FRP)-confined concrete cylinders

This paper presents an experimental study on the impact performance of concrete columns confined with largerupture-strain (LRS, tensile rupture strain >= 5%) fiber reinforced polymer (FRP) jackets. A total of 32 concrete specimens were prepared and tested using large-capacity drop-weight equipment. The test variables included four impact heights (2, 3, 4 and 5 m), three types of FRP, i.e., aramid FRP (AFRP), polyethylene naphthalate (PEN) FRP and polyethylene terephthalate (PET) FRP and two layers of FRP jackets (1 and 2). The time histories of impact force and FRP rupture strain as well as failure modes were obtained from the test. Compared to the AFRP-confined concrete specimen with similar jacket stiffness, the core concrete of the LRS FRP-confined specimen was less damaged due to the large-rupture-strain characteristic. The impact force increased and the impact duration decreased with increasing impact height. The impact duration of concrete specimens confined with LRS FRP was longer than that of the AFRP-confined concrete column. Results showed that the impactresistance behaviours of LRS FRP-confined concrete column outperformed its companion column confined with AFRP. Besides, increasing the thickness of FRP jacket can enhance the impact resistance capacity. These findings may facilitate the impact resistance strengthening/retrofitting of RC structures with the application of LRS FRP composites.