Axial Impact Resistance of FRP-Confined Concrete

Abstract

This study investigates the impact resistance of fiber-reinforced polymer (FRP) confined concrete. Concrete cylinders were wrapped with carbon FRP (CFRP) or glass FRP (GFRP) with a varied number of layers and wrapping schemes. The impact tests were conducted by using drop-weight apparatus at different impact velocities. Dynamic behavior of the specimens has been investigated. The experimental results have shown that the failure modes are very different than those from static tests. Identical specimens experienced different damage as the impact velocities changed. The dynamic rupture strain of FRP was found to be substantially lower compared with that under static loads. As a result, the FRP efficiency factors were 0.17 and 0.56 for CFRP and GFRP, respectively. Interestingly, although GFRP has lower tensile strength and elastic modulus, it showed much better performance against impact compared with CFRP in terms of both the strength and ductility. The higher rupture strain of GFRP compared with CFRP results in higher confinement efficiency of GFRP under impact loads. A confinement model is proposed to predict the confined concrete strength under impact.