Experimental investigation on distortional performance of cold-formed steel built-up channel columns with web-stiffeners under eccentric compression

The compression tests of 22 cold-formed built-up H-shaped steel columns with V-shaped web stiffeners and openings were carried out to study the distortion buckling performance of the built-up members under eccentric load. The applicability of calculation methods in the current Chinese and American standard was evaluated. The failure mode and ultimate bearing capacity of each specimen were obtained by changing the length of the column, the position and number of openings, the bending direction around the strong axis and the weak axis, and the size of the eccentricity. The test results show that all specimens present distortion buckling or buckling mainly due to distortion, and the distribution of distortional half-waves is affected by holes and stiffeners. The direction and size of the eccentricity around the strong axis and that around the weak axis have a significant effect on the ultimate bearing capacity. The test ultimate capacity was studied using the calculation method in the current Chinese and American standards. The results show that the calculation results of GB 50018—2002, JGJ / T 421—2018, and NAS100-16 are all safe when calculating the eccentric compression bearing capacity around the strong axis. When calculating the eccentric compression bearing capacity around the weak axis, the calculation results of GB 50018—2002 and NAS100-16 are both safe and reasonable. The average ratios of the test results divided by GB 50018—2002 and NAS100-16 codes are 1. 16 and 1. 15, respectively, while that of the test results to the calculated results of JGJ / T 421—2018 is 1. 66, which is relatively conservative. It is recommended that when the two limbs of the built-up member are reliably connected, the eccentric compression bearing capacity around the weak axis should be calculated according to the overall section. © 2022 Science Press. All rights reserved.