Steel basement columns have rusted and split open
A lot of variables... one of the most important is what load they are supporting and how badly are they rusted aside from the split. Unless you are in a position to accurately gauge their "importance" to the structure you really should consult a qualified contractor.  From the look of the photo there appears to be some buckling where the seam has split which seems very unusual to me and cause for concern.  The good news is that if everything else is OK, it's a pretty simple and inexpensive repair.