Test, numerical investigation and design of perforated advanced high-strength steel I-shaped built-up compression members

This study investigates the effects of perforations on the buckling behavior and load-bearing capacity of advanced high-strength steel I-shaped built-up compression members. The built-up section was fabricated by connecting two identical lipped channel sections made of complex phrase steel HC700CP980 using pull rivets. The perforations were classified into two groups: holes in web and holes in both web and flanges. A comprehensive parametric study, combining both experimental results and finite element analysis, demonstrated the decrease in load-bearing capacity caused by the presence of perforations, particularly noticeable in specimens featuring holes in both web and flanges. The extend of the reduction is closely linked to the quantity and dimensions of the holes, with a higher hole-element width ratio resulting in a more substantial loss of load-bearing capacity. Additionally, the obtained test and FE results were used to evaluate the accuracy of direct strength method (DSM) for the examined advanced high-strength steel I-shaped built-up compression members. The evaluation findings highlight the limitations of the DSM in the design predictions for built-up columns featuring multiple web holes and holes on both web and flanges. Therefore, a modified calculation method was proposed, which integrated strength reduction factors to consider the influence of the position of holes relative to the flexural buckling axis of built-up sections. The modified method has shown notably improved design accuracy and consistency for the perforated advanced high-strength steel I-shaped built-up sections.