Systematic Review on the Behaviour of Carbon and Stainless Steel Reinforcing Bars in Buildings Under High Temperatures

Carbon and stainless steel reinforcing bar behaviour at high temperatures and subsequent cooling is central to fire safety for buildings. This systematic review examines the peer-reviewed literature between 2015 and 2024, concentrating on mechanical performance, microstructural transformation, and responses under various cooling conditions. Since experimental studies on some reinforcing steels in building construction are scarce, based on the selection criteria, they were selected on different standards. Austenitic stainless steels like show better thermal stability, here determined by their ability to preserve mechanical strength and ductility after exposure to fires, compared with carbon steel. Several studies indicate that rapid cooling, especially after exceeding critical transformation temperatures, can induce the formation of martensitic structures in carbon steel. These structures can increase toughness but often lead to reduced ductility and a more brittle mechanical response. These effects are particularly relevant in contexts where structural elements remain in service after a fire. The methodology adheres to PRISMA guidelines, providing transparency and an easily traced choice process. Key gaps in the post-fire performance of reinforcing bar in buildings are established by this review, with future directions in standard fire tests and an examination of effects from cooling under conditions that mimic building settings.