Impact Behavior of FRP-Strengthened Reinforced Concrete Members: A Systematic Review of Experimental and Numerical Advances (2016–2025)

Fiber-reinforced polymer (FRP) strengthening has become a widely adopted technique for retrofitting reinforced concrete (RC) structures, yet current design codes do not address impact loading despite the documented vulnerability of infrastructure to vehicle collisions, crane strikes, and debris impacts. This paper presents a systematic review of experimental, numerical, and analytical developments in the impact behavior of FRP-strengthened RC beams, columns, and slabs published between 2016 and 2025. The experimental evidence establishes that FRP strengthening improves impact resistance by 20 to 60 percent and reduces peak displacement by 25 to 40 percent, with full wrapping configurations consistently outperforming partial schemes and carbon FRP providing superior stiffness enhancement while glass and basalt FRP offer greater energy absorption capacity. Validated finite element simulations using ABAQUS/Explicit and LS-DYNA with concrete damaged plasticity and Hashin damage criteria reproduce experimental trends with sufficient accuracy to support parametric exploration beyond laboratory constraints. A critical mechanistic finding is that FRP strengthening shifts the failure hierarchy from brittle shear collapse toward ductile flexural responses, though debonding at the FRP-concrete interface remains the dominant performance limit. Parametric synthesis identifies two to three FRP layers and axial load ratios of 0.1 to 0.2 as optimal for impact applications. The absence of impact provisions in ACI PRC-440.2-23 and fib Bulletin 90 constitutes the most consequential gap between research knowledge and engineering practice, with repeated impact characterization, dynamic bond-slip quantification, and full-scale validation identified as priority research needs for future code development.