Sensitivity of lateral impact response of RC columns reinforced with GFRP bars and stirrups to concrete strength and reinforcement ratio

This is the first study in the literature which experimentally and numerically investigates the impact behavior of concrete columns reinforced with fiber-reinforced polymer (FRP) reinforcements. The effect of concrete strength (50 MPa vs 100 MPa) and longitudinal FRP ratio on the lateral impact response of the columns was investigated. The experimental results showed that the longitudinal reinforcement ratio strongly affected the failure modes and impact-resistant capacity while the use of high strength concrete (HSC) did not effectively improve the performance of the columns, which on the contrary, might have caused spalling failure due to its brittleness. The peak impact force and displacement of the columns increased linearly with the impact velocity up to their maximum capacity. The longitudinal reinforcement ratio slightly affected the peak impact forces while the concrete strength showed marginal variation. The use of HSC did not effectively reduce the maximum displacement of the columns. The energy absorption of the columns and the impact velocity exhibited an approximately linear relationship regardless of the reinforcement ratio and concrete strength. Different from the static case, the numerical results show three critical sections, i.e. at the impact location and column ends, which need to be carefully designed.