Behavior of reinforcement concrete columns exposed to fire at an early age

Fires harm the behavior of concrete members, especially columns, as fire is considered one of the most important causes of deterioration in the properties and behavior of concrete. This research was conducted for eighteen concrete columns according to several variables such as the age of the columns, compressive strength, and the period of exposure to fire. The specimens were distributed into four groups based on concrete mix type and age at exposure to fire. Each group contains four columns, the first being a reference, and the other three columns are exposed to fire periods of one hour, one and a half hours, and two hours. The columns at the age of 28 days showed better strength compared to the columns of 15 days and columns of 7 days age for the same type of concrete mix. When studying fragmentation and separation, columns with lower compressive strength showed better behavior than columns with high strength. The residual strength of the four groups when the specimens were exposed to fire for two hours ranged from 24% to 38%. The effect of varying periods of fire on the compressive strength of concrete cubes at different ages was studied.