Flexural performance of square concrete-filled steel tube beams stiffened with V-shaped grooves

The outward steel tube buckling failure of concrete-filled steel tube (CFST) beams is still considered to be a serious concern due to the typical bending loads. This research conducts experimental and numerical investigations on the flexural performance of slender square steel tubes filled with normal concrete. A total of 6 cold-formed square CFST specimens were tested under static bending loads. The cross-sections of 4 specimens were stiffened by single and double V-shaped grooves along the tube cross-sections, and 2 specimens were tested as control specimens (unstiffened square specimens). The results showed that adopting this stiffening concept in the slender square CFST beams led to restriction of the buckling failure of the outward steel tube (at the top flange). Due to the increase in the steel confinement factor of the stiffened square CFST beams, the bending moment capacity, flexural stiffness, and energy absorption capability were improved by 25.4%, 7.2%, and 31.4%, respectively, compared to those of the corresponding unstiffened specimens. Finite element models were also developed to further investigate the performance of the proposed CFST specimens by varying certain chosen parameters. The bending moment capacity and the flexural stiffness results obtained from the experimental and numerical investigations were validated with predicted values from different existing standards. (C) 2020 Elsevier Ltd. All rights reserved.