Abstract
This paper experimentally investigates the effect of high-temperature fire on the structural behavior of reinforced concrete hollow columns. Sixteen square (120×120mm) columns were fabricated with 600mm length. The experiment's parameters were: the hollow size and the temperature of fire. Twelve specimens were cast with a hollow cross-section by inserting PVC pipes centrally along their length; these columns were categorized into three groups depending on the hollow diameters: 25.4, 50.8, and 76. 2mm. The remaining samples were solid and gathered in one group. Each group contained four samples; three of them were burnt at 300, 500, and 700 oC for one hour, and the fourth one was a reference not exposed to fire. All columns were tested under an axial compressive loading applied progressively up to the column’s collapse. The experiment results indicated that the collapse load of columns, having a same cross-sectional area, decreased with increased the temperature. The decline in columns’ strength ranged from 20.00% to 68.67% for specimens exposed to 300-700oC temperature, respectively. Additionally, for columns exposed to the same temperature, the collapse load descended as the hollow size augmented. A decrease of failure load varied from 21.86% to 65.38% for 25.4 to76.2mm hollow size columns, respectively. Finally, columns' stiffness reduced with increasing the temperature and the hollow size.
