The Effect of Fire on the Behavior of Perforated Short Steel Compression Members and Evaluation after Retrofitting

Steel is one of the most widely used materials in structures due to its high strength and speed of execution. One of the most important disadvantages of steel is corrosion damage and low fire resistance. When the temperature of the steel exceeds a certain value, its strength decreases to a great extent; therefore, in this paper, the performance of canned steel specimens with corrosion and at different temperatures has been investigated. Thus, the corrosion weakness is considered as a perforation and the columns with different positions of the perforation in 6 states and the application of heat in 5 different states 20, 100, 250, 500, and 700 are examined and the load-displacement diagrams of each column under axial loading are presented. Then, in order to improve the behavior of the damaged specimens by the two mentioned factors, the perforation location has been reinforced and reinforced using a steel sheet and axial loading has been done in two-temperature states of 20 and 700 ° C. The results show that: with increasing temperature, the bearing capacity of unreinforced columns has decreased and this reduction has reached up to about 15% for perforated specimens and up to about 35% for perforated specimens according to the type of perforation. Also, in steel columns reinforced with steel sheets, the bearing capacity has increased by about 5 to 15 percent (depending on the perforation).