Behavior of Reinforced Concrete Columns Exposed to Elevated Temperature

The present study includes the behavior of reinforced concrete columns under elevated temperature. Four specimens of columns were cast for this purpose, with a constant length of 540 mm and a constant sectional area of 100×100mm, with a curing time equal to 28 days. Then, the specimens are exposed to elevated temperatures (150, 300, and 600 °C) and to room temperature. After air-cooling, the specimens are examined as hinged-hinged supported columns with a point load applied at the top of the column. The ultimate load capacity, mid-lateral deflection, mid-axial displacement, failure mode, and crack formation are investigated. The results indicate an appreciable effect on the strength of columns caused by exposure to high temperatures, which is greater than 300 °C, where a decrease in the value of ultimate load is observed when subjected to a temperature level of 600 °C, where the ultimate load becomes 35.2% of the original value. Additionally, the specimens exhibit large deformation under extreme temperatures, resulting from a substantial drop in column stiffness; the stiffness of the column heated to 600 °C decreases by about 55.5% relative to that at ambient temperature.