Experimental and numerical study on corroded cold-formed thick-walled SHS stub columns

This study experimentally and numerically investigates the axial compressive performance degradation of corroded cold-formed thick-walled square stub columns. Five specimens with different corrosion ages were produced using accelerated corrosion, and 3D laser scanning was used to obtain the actual corrosion morphology and characteristic parameters. Axial compression tests were then conducted to evaluate failure modes and load–displacement responses. The results show pronounced spatial non-uniformity of corrosion, and buckling typically occurs in height segments with more severe corrosion loss. The ultimate load decreases with increasing corrosion severity, with a 12.8% reduction at a 5.99% mass loss rate. To accurately simulate the axial compression response of corroded stub columns, an FE modelling approach coupling the cold-forming process with the measured corrosion morphology is proposed and validated against the tests. A parametric study involving 35 FE models was further conducted to investigate the degradation trends in axial compressive resistance with increasing corrosion severity for sections with different width-to-thickness ratios. Finally, the applicability of EN 1993, AISI S100, and GB/T 50018–2025 was assessed using the experimental and parametric finite-element results. Among the three design provisions, AISI S100 provided the closest agreement with the experimental and finite-element results and was therefore selected as the basis for developing a modified resistance method. The proposed method showed good agreement with the parametric finite-element results.