Impact resistance of ultra-high strength concrete beams with FRP reinforcement

Composite materials, including Fibre Reinforced Polymer (FRP) bars, have been used for decades in the structural and civil engineering sectors over traditional steel reinforcement. The main reasons for this are that FRP composites possess a number of advantages. They are non-corrosive, non-conductive, and lightweight and possess high longitudinal tensile strength. This paper presents the results of an experimental investigation into the effects of the use of glass FRP (GFRP) bars as internal reinforcement on the behaviour of concrete beams with high strength concrete (HSC) and ultra-high strength concrete (UHSC). Both static and dynamic (impact) behaviours of the beam have been investigated. Twelve GFRP reinforced concrete (RC) beams were designed, cast and tested. Six GFRP RC beams were tested under static loading (three point bending) to examine the failure modes, load carrying capacity, deflection and energy absorption capacities. The other six GFRP RC beams were tested under impact loading using a drop hammer apparatus at various levels of impact energy. It was found that the use of UHSC in conjunction with larger amounts of tensile reinforcement showed higher levels of post-cracking bending stiffness. GFRP RC beams under static loading displayed a flexural response at failure. The GFRP RC beams under impact loading displayed a dynamic punching shear failure response at various levels of impact energy.