I'm having some work done in the UK (Eurocode) which involves a steel column to support a beam at 1st floor (US: 2nd floor?) level. The column bears a very-close-to-vertical total load of 47.3kN (including any relevant safety factors I guess, as that's the final figure in his calcs).
The engineer has specified a 152x152 23kg UC to be used for the column, with suitable end+base plates and fixings.
My issue is that the engineer has offered a low rate as its for a "charity job" (house belongs to an elderly frail relative). I've gone back to him with a set of 3 queries and got replies that are professional but curt and I don't want to go back again to ask if anything else is possible, unless I'm already privately very sure it is and can back it with calcs, as I don't want to lose his goodwill.
The only time he's said yes to any change, was when I also attached calcs to justify why I thought it should be OK. Unhelpful and not my job, I know!
In this case, I really need a slimmer column, to run flush with the 100mm partition wall. Unfortunately I don't understand column slenderness calculations well enough to check if there's scope to replace the 3m 152x152 23kg UC by, say, a 100x100x10 25kg RHS, or even a 100x180x5 21kg RHS. My tentative figures suggest that because of the RHS vs UC profile, both of these would be stiffer in any direction, than the UC and they'd fit nicely flush to the wall, so maybe they'd work.
I don't need an absolute calculation ("Does this profile work for that length and load"), but only a relative one ("Would this profile be at least as satisfactory as the one he's already said is good enough")?
What calculations are needed, to confirm if a more slender (in one dimension at least!) RHS profile would be at least as satisfactory/rigid in performance as a column, compared to the currently-proposed UC?