Slightly snarky answer: the one that your licensing authority will accept.
Plastic softening of structures is one of those subjects on which one can spend a year on an experiment, which will be valid for that config. BTDT, got great answers. But did it really mean we could confidently design for compression? No.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
free flanges would be limited by fcc (that'd be crippling stress, not the federal communiations commission). typically fcc is limited to fcy. to go beyond that, a series of tests (and the anticipation of failure !?)
I'm sorry, but I disagree with rb1957. You can not cripple sections which are flat. You need corner in order to get a "crippling stress."
Wingsmith, I recommend you take a look at the Handbook for Stability (do a search in the NACA Technical Report Server for that title). I've done some research on the topic and have found useful information in the NACA report.