Experimental investigation of the behavior of reinforced concrete structural elements exposed to fire

Fire is one of the most serious and dangerous situations that a reinforced concrete (BS) building can encounter during its service life. Reinforced concrete members lose significant strength and stiffness when exposed to fire, and the majority of the strength loss is irreversible. This is due to the temperature rise of concrete and steel reinforcement, as well as the deterioration of material properties. Within the scope of this study, five (5) reinforced concrete columns with the same cross-section and reinforcement configuration were produced, one of which serves as a reference element. The reference element was only subjected to four-point static loading and was not exposed to fire. The other four test elements were only exposed to fire from their lower surfaces for 90 minutes. The test elements were subjected to four-point static loading tests after being allowed to cool at room temperature. The yield strength and stiffness of fire-exposed elements decreased by 12% to 20%. The fracture mode observed in the specimens was typically bending cracks that began in the tensile zone and progressed to the compression zone. Furthermore, because of the loss of strength in concrete and reinforcement steel, the elasticity modules of the fire-exposed elements decreased by 60% when compared to the reference element.