Reinforced Concrete Beams with FRP and Hybrid Steel-FRP Composite Bars: Load-Deflection Response, Failure Mechanisms, and Design Implications.

Corrosion concerns motivate the use of alternatives to conventional steel reinforcement in RC beams. This review evaluates fiber-reinforced polymer (FRP) bars and hybrid steel-FRP composite bars (SFCBs) used for durability-critical applications. We conducted a structured literature search focused on 2010-2025 and included seminal pre-2010 studies for context. Experimental studies and code provisions were screened to synthesize evidence on load-deflection response, cracking, and failure, with brief notes on UHPC systems. FRP-RC offers corrosion resistance but limited ductility and an abrupt post-peak response. Steel is ductile and provides warning before failure. SFCB combines durability with steel-core ductility and yields gradual softening and higher energy absorption. Practice should select reinforcement based on stiffness-ductility-durability trade-offs. Current codes only partially cover hybrids. Key gaps include standardized bond-slip and tension-stiffening models for SFCB and robust data on long-term performance under aggressive exposure.