Review of Flexural Design Parameters of Concrete Cross-Sections Strengthened with FRP Laminates

The deterioration of concrete structures, often accelerated by corrosion, poses significant challenges to structural integrity and maintenance costs. Fibre Reinforced Polymer (FRP) composites offer a promising solution for strengthening and rehabilitating Reinforced Concrete (RC) structures due to their high strength-to-weight ratio, corrosion resistance, and cost-effectiveness. This paper provides a comprehensive review of flexural design parameters for concrete cross-sections strengthened with FRP laminates, with a focus on the guidelines established in ACI 440.2R-17. It outlines the primary factors influencing the design, including the impact of FRP thickness, steel reinforcement ratio, concrete compressive strength, span-todepth ratio, and the arrangement of FRP. Key findings include the significant enhancement of flexural strength with increased FRP thickness, with a maximum observed improvement of up to 35%. The study also highlights that the optimal FRP reinforcement ratio varies depending on the steel reinforcement ratio and concrete compressive strength. The failure mode transitions from concrete crushing to FRP debonding or rupture depending on these parameters. An analytical procedure, incorporating a detailed flowchart and code developed in Visual Basic Applications for Excel, facilitates the analysis of these parameters. The paper also underscores practical recommendations for FRP application, emphasizing that side-bonded FRP sheets may be less effective than bottom-bonded sheets and should be used cautiously. Overall, this review aims to provide a thorough understanding of the design considerations for FRP-strengthened concrete beams, enabling engineers to optimise their use of FRP composites in structural retrofitting.