Structural performance evaluation of deficient steel members strengthened using CFRP under combined tensile, torsional and lateral loading

Abstract

In recent years, strengthening of members of steel structures with square hollow sections (SHSs) using carbon fiber reinforced polymers (CFRPs) has attracted the attention of many researchers. Most previous research in this area has been done on the behavior of CFRP strengthened steel sections without deficiency. During the lifetime of structures, some members may be placed under combined loads. To the author's knowledge, no research on the behavior of CFRP strengthened deficient SHS steel sections subjected to combined tensile, torsional, and lateral load has been presented. The deficiency in steel sections may be created due to errors caused by construction, fatigue cracking, drilling after construction, corrosion, earthquake damage, and so on. This study explores the effect of the use of adhesively bonded CFRP flexible sheets on the structural behaviors of deficient SHS steel sections under combined tensile, torsional, and lateral load, using numerical investigation. To study the effects of the CFRP strengthening method on recovering the strength lost in deficient SHS steel sections, 17 specimens, 12 of which were strengthened using CFRP sheets, were analyzed. To analyze the SHS steel sections, three dimensional (3D) modeling and nonlinear static analysis methods using ANSYS software were applied. The results showed the deficiency led to reductions in ultimate capacity of the SHS steel sections under combined tensile, torsional, and lateral load. Also, the impact of transverse deficiency was higher than the longitudinal one in these sections. Using CFRP for strengthening the deficient SHS steel sections showed that CFRP has an impact on raising the ultimate capacity and can significantly recover the strength lost due to deficiency.