Effect of using CFRP on the Bearing Capacity of Defected Four-Angle Ateel Composite Columns

<div>The main goal of the current research is to study the strengthening of defected four angle steel composite columns using carbon fiber reinforced polymer (CFRP). Therefore, using numerical studies carried by Abaqus, 19 composite steel column models including 1 sample without defects, 9 samples with vertical defects and 9 samples with horizontal defects, with and without the use of CFRP confinement were investigated. After investigating the effect of defect dimensions and the presence of CFRP on the bearing capacity of the studied columns, 5 samples of numerical models were selected and built for experimental investigation. The results obtained from this study showed that the presence of defects in the four-angle steel composite column has reduced the bearing capacity of the column. So that, on average, the bearing capacity of samples with horizontal defects of 15, 30 and 45mm width has been reduced by 0.62%, 1.43% and 8.5%, respectively, compared to the witness model. This decreasing trend regarding the columns with vertical defects by the height of 75, 150. 225mm is equal to 0.63%, 2.19% and 2.42% respectively. Other results showed that the use of CFRP increases the bearing capacity of the columns. So that the maximum load capacity increase of columns with horizontal and vertical defects due to the use of CFRP is 77.5% and 68.2% respectively. Also, the comparison of numerical and experimental results showed a good agreement. The maximum difference between numerical and experimental results of bearing capacity of the columns is only 0.91%.</div>