Flexural performance of reinforced concrete beams exposed to uncontrolled fire with and without plaster protection

Fire analysis of reinforced concrete (RC) structures is vital for understanding their behavior under extreme conditions. In real-world scenarios, uncontrolled fires can damage buildings and infrastructure substantially, undermining their structural integrity. Assessing the performance of RC beams under fire exposure is crucial for ensuring the safety and reliability of structures. This study examines the structural performance and residual moment capacity of plastered and unplaster-reinforced concrete (RC) beams subjected to varying durations of fire exposure. Two types of reinforcement configurations in plastered and unplaster beams were evaluated: one with two 10 mm diameter reinforcement bars at the top and bottom and another with two 10 mm diameter bars at the top and three at the bottom. Unplaster and plastered beams were made from concrete with a compressive strength of 20 MPa at ambient temperature. They were exposed to fire for durations of 0, 3, and 6 h, simulating real fire conditions with a peak temperature of 800 °C. Beams exposed to fire showed reductions in moment capacity of about 20-36%, depending on the reinforcement. The findings highlight the importance of considering plaster as a protective layer in RC beam design to enhance fire resistance and post-fire structural performance. The findings emphasize the necessity of incorporating fire-resistant measures, such as plaster coatings, to mitigate structural degradation, thereby enhancing post-fire safety and performance of RC beams.