Strengthening of Reinforced Concrete Beams Using FRP Composites: A Review

Reinforced concrete (RC) structures are prone to gradual deterioration over time, influenced by factors such as increased service loads, exposure to highly aggressive environmental conditions, and the natural aging of materials. Among the various retrofitting techniques available, the use of Fiber-Reinforced Polymers (FRP) externally bonded composite materials has proven to be one of the most effective solutions for restoring or even enhancing the structural performance of such elements. This paper presents a thorough review of over sixty experimental, analytical, and numerical studies focused on the application of FRP composites in strengthening RC beams. It critically examines advancements in FRP technology, material characteristics, and key parameters such as fiber type, orientation, bonding configuration, and failure mechanisms. Additionally, significant attention is given to finite element modelling (FEM) approaches and model-selection strategies employed to simulate the structural behaviour of FRP-strengthened beams. Key challenges, including nonlinear material modelling, bond behaviour at interfaces, and premature debonding issues, are addressed. The paper also highlights essential research directions needed to develop reliable performance-based design and analysis frameworks