Post‑fire evaluation of SHS retrofitted steel columns

摘要

In this paper, the performance of square hollow section (SHS) steel columns with defect at different temperatures is investigated. Accordingly, the columns are constructed with different locations of the defect in 6 modes. The specimens are also exposed to five temperatures of 20 degrees C (ambient temperature), 100 degrees C, 250 degrees C, 500 degrees C, and 700 degrees C. Afterward, the columns are subjected to axial loading, and force-displacement curves of each column are presented. Then, to improve the behavior of the damaged columns by the two mentioned factors, the specimens of defective columns at two temperatures of 20 degrees C and 700 degrees C, are retrofitted using steel plates. The results of the specimens show that with increasing temperature, the bearing capacity of the columns decreases, which is about 15% for defectless columns at 700 degrees C and up to 35% depending on the type of defect for defective specimens. Also, comparison of different defects indicates that the maximum decrease in bearing capacity of column specimens with horizontal defect and vertical defects is related to the defect located at the middle of the column at 20 degrees C and at the bottom of the column at 700 degrees C, respectively. Finally, by retrofitting the defects of the columns with steel plates, the bearing capacity of the columns at 700 degrees C increases about 13%.