Investigation of the Structural Behavior of Reinforced Concrete Beams at Elevated Temperatures.

Reinforced concrete structures encounter a range of detrimental external factors over their operational lifespan. One of them is the elevated temperature effect due to fires. Conversely, due to the influence of global warming, temperatures are on the rise worldwide, leading to an increase in fire incidents. Owing to the increasing rates of construction and fire incidents, it becomes imperative to investigate the durability of reinforced concrete members when exposed to high temperatures. This experimental study aims to assess the structural behavior of reinforced concrete beams following exposure to elevated temperatures. To accomplish this goal, concrete cube specimens, steel rebars, pull-out specimens, and reinforced concrete beams were exposed to elevated temperatures of up to 800 °C and then allowed to cool in air. Following this, all specimens were subjected to testing in accordance with the relevant codes and standards. Test results were analyzed through comparison. In a comprehensive examination of the results, it is evident that the concrete compressive strength experiences an approximately 55% reduction at 600 °C. Meanwhile, there is no notable decrease in the yield strength of the steel at this temperature. However, at 800 °C, steel yield strength decreases by nearly 30%, while the compressive strength of the concrete decreases by a significant 82%. This indicates a substantial reduction in the load-bearing capacity of the beam specimens due to concrete deterioration and the subsequent decline in the bonding performance between concrete and steel rebars.