CAESAR II is a beam element program that does not adress localized shell effects, nor does a beam element analysis model evaluate prying action on flanges.

Having said that I would say your former approach was grossly simplified and failed to look at other important items. But it was a lot quicker than doing a more thorough job, sometimes you don't need to look into everything, sometimes you do... the importance of sound engineering, and experience based judgement can not be overstated enough...