Effects of Vertical Deficiency Location on the Structural Behavior of Steel SHS Short Columns

Structures that face damage require strengthening to reach the initial performance. Strengthening steel Square Hollow Section (SHS) short columns with initial deficiencies were not taken into account appropriately. In this paper, vertical deficiencies with the same dimensions were created at three locations (top, middle, and bottom) on the middle element and the middle of the corner element. Then, the effect of the location of such deficiencies on axial behavior of Carbon Fiber Reinforced Polymer (CFRP) strengthened steel tubular columns was investigated. To this end, a total of nine steel columns were experimentally tested and the same specimens were modeled using ABAQUS V.6.14. In the experimental work, a straight pressure test was performed. In the numerical simulation, three dimensional (3D) simulation method, static gradual loading, and non-linear static analysis were used. The specimens were: no deficiency (Control), four non-strengthened columns with deficiencies at different locations, and four CFRP strengthened specimens having deficiencies. The results showed that vertical deficiencies caused a significant decrease in load-bearing capacity and initial performance. As a result of axial loading, the area of vertical deficiencies experienced local buckling increase and lateral rupture. Local bucking at damaged locations caused the stress concentration, then the axial deformation increased. Vertical deficiencies at the bottom of the middle element caused the most critical conditions. Vertical deficiencies on the corner element led to greater destruction and bearing capacity decline compared to the middle element. Carbon Fiber played a key role in ductility and strength increase around the deficiency by covering it. Using CFRP layers the stress concentration overcame and the local buckling delayed due to high confining strength.