Farid Abed

Fiber-reinforced polymers (FRP) bars have gained widespread recognition as a viable alternative to steel reinforcement in concrete structures over the past decades due to their advantages in corrosion resistance, durability, and lightweight properties. However, existing research and current design codes do not adequately address the dynamic compressive response of FRP bars under high-impact loading conditions. This gap in knowledge presents a significant challenge in accurately predicting the response of FRP-reinforced structures under extreme loading events. Therefore, it is essential to investigate the response of FRP bars under dynamic loading conditions across a range of strain rates to improve design codes and ensure the reliability and safety of structures subjected to such conditions. This study presents an experimental program conducted on basalt FRP (BFRP) bars subjected to dynamic testing using the Split Hopkinson Pressure Bar (SHPB) apparatus. The 12-mm BFRP bars are subjected to impact loading at high strain rates ranging from 345 to 1300 s ^-1 . These varying strain rates are achieved by adjusting the pressure of the impact bar. A high-speed camera is employed to capture the failure mechanisms and provide visualization of the deformations during loading. The study focuses on evaluating the stress-strain relationship and failure modes of the tested BFRP bars under various loading rates. The results revealed that at higher strain rates of ∼1300 s ^-1 , BFRP bars lost 40% of its compressive strength when compared to its quasi-static strength (tested at 3.5 x 10 ^-4 s ^-1 ). At lower strain rates (∼345 s ^-1 ), 20% of the quasi-static strength is lost. At intermediate strain rates (∼590-740 s ^-1 ), one sample showed a strength reduction of 26%, while another sample showed a strength gain of 10%. This proves that BFRP bars are highly strain-rate dependent. Additionally, the results show relatively significant variation in the behavior of the samples at similar strain rates, indicating microstructural differences between them.