Enhancing fire resistance of reinforced concrete beams through sacrificial reinforcement

Due to the superior properties of concrete, structural members made of concrete often satisfy fire requirements specified in codes and standards without special installations or the use of external insulation. A closer examination into fire codal provisions shows that they are primarily founded for new constructions or that which does not suffer from aging or in-service trauma; such as cracking, reinforcement corrosion, creep, etc., all of which can adversely affect the structural response of concrete structures, especially under fire conditions. In order to enhance the fire resistance of concrete structures, this paper presents insights into simple and cost-effective solutions by utilizing sacrificial layer(s) of reinforcement. These solutions capitalize on the natural synergy between reinforcement and concrete and have the potential to mitigate fire-induced cracking and the development of fire-induced large deformation, thereby extending the fire resistance of reinforced concrete beams. The validity and applicability of the proposed concepts are highlighted through a highly complex three-dimensional thermo-mechanical nonlinear-based finite element model. This model was utilized in a series of parametric studies to examine critical parameters influencing the fire response of concrete beams reinforced with steel and fiber-reinforced polymer reinforcement. These parameters include sacrificial reinforcement scheme, size, and material type. It was concluded that the use of sacrificial reinforcement could be beneficial for mitigation purposes or as a repair solution for postfire events.