Investigating and copmaring the most effective methods to improve post-fire performance of steel short columns with vertical and horizontal defects

In this paper, the performance of box steel columns with corrosion is investigated. Thus the steel columns are made with different defect locations (6 modes) and are subjected to temperatures of 20 °C and 700 °C. Then, two retrofitted methods (CFRP composites and steel plates) are used in the defect area in order to improve the performance of columns. Afterwards, bearing capacity of all column specimens (38 specimens) has been obtained. The results indicate a decrease in the bearing capacity of the columns and weakness in their performance due to the two factors of defect and heat so that the greatest decrease in the column compression strength is about 32% and 35% due to defect and high temperature, respectively. Also, the comparison of retrofitting methods indicates that the use of composite is more effective in improving the performance of steel columns. Finally, For further investigation, 5 specimens are modeled in ABAQUS finite element software and the results are compared with similar experimental results.