This　paper　presents　an　experimental　and　numerical　investigation　into　the　minor　-axis　flexural　buckling　behavior　of　Q1100　ultra　high　strength　steel　(UHSS)　welded　I　-section　columns.　A　total　of　8　column　specimens,　spanning　two　different　sections,　were　tested.　Finite　element　(FE)　models　were　developed　to　replicate　the　experimental　observations,　and　these　models　were　subsequently　employed　in　a　parametric　investigation　that　encompassed　a　wider　range　of　specimen　geometries.　Concurrently,　a　comprehensive　evaluation　of　the　buckling　curves　outlined　in　European,　North　American,　Australian,　and　Chinese　codes　was　performed　through　rigorous　reliability　analyses.　Furthermore,　this　study　conducted　a　comparative　analysis　between　the　effective　width　method　(EWM)　and　the　modified　direct　strength　method　(DSM)　for　slender　cross　-sections.　Based　on　the　outcomes　of　the　reliability　analyses,　revised　buckling　curves　are　proposed,　which　are　specifically　aimed　at　enhancing　the　design　provisions　for　addressing　minor　-axis　flexural　buckling　in　Q1100　ultra　high　strength　steel　welded　I　-section　columns.