Cold-formed steel (CFS) structural members are widely used in residential construction due to their favourable properties and advances in manufacturing. To improve thermal performance, slits are often introduced into the webs of these members. However, this alteration can compromise their axial strength. Although this has important structural implications, few studies have quantified the effect of slits on axial capacity, particularly under eccentric loading conditions. The authors previously examined slitted CFS sections under concentric axial compression and through this research address that gap by conducting a comprehensive parametric study on CFS studs with slits, subjected to combined axial compression and minor axis bending through eccentric loading. A total of 1134 finite element analysis (FEA) models were created, varying parameters such as member length, thickness, cross-sectional dimensions, and six different load eccentricities. These models evaluated how slits influence axial capacity when minor-axis bending occurs due to eccentric loads. The FEA results were compared with predictions from the general interaction equation provided in the Australian/New Zealand Standard AS/NZS 4600. On average, the design equations underestimated the strengths by approximately 13% for eccentricities ranging from 10 mm to 25 mm, while they overestimated the strengths by about 20% for 50 mm eccentricities. Based on these findings, a new design interaction equation was developed, incorporating element and web slenderness ratios. A reliability analysis within the AISI-S100 framework confirmed that the proposed design modifications satisfy required safety standards.
Ghosh et al. (Thu,) studied this question.