post buckling strength
post buckling strength
(OP)
Is the idea behind post buckling strength of columns this: A column that buckles elastically has much higher post-buckling strength than a column that buckles inelastically because the elastic column has greater moment capacity for no other reason than the section hasn't yielded and lost capacity? Once the column begins yielding, then buckles, its moment capacity (and, as a result, its post-buckling strength) is greatly reduced.






RE: post buckling strength
as i think you're implying, once a column starts to buckle in compression, wouldn't it be the equivalent of a plastic hinge and so the allowable load would drop significantly.
just possibly there are some "funky" designs whereby a small part of the section can buckle and the rest of the section can remain stable, and so take additional load ??
RE: post buckling strength
The system as a whole has not buckled becuase of your stiffened areas.
So codes allow you to take an increase in strength to account for the time between local buckling (individual components) and gobally buckling (overall section).
RE: post buckling strength
RE: post buckling strength
Mike McCann
MMC Engineering
RE: post buckling strength
RE: post buckling strength
Where did you find the info you are referring to? I was not aware that columns are counted on for postbuckling strength, especially elastic buckling. Elastic buckling is due to the column being long or slender, so after buckling I couldn't imagine it having any strength after buckling due to instability.
RE: post buckling strength
It definitely doesn't have anything to do with elastic vs inelastic overall member buckling.
Here's the easiest explanation I can think of, contrasting overall member buckling vs local buckling with post-buckling strength.
With overall member buckling such as flexural buckling or LTB, once the member begins to buckle, that's pretty much it. Its load can't be increased much or at all.
Now imagine a web of a vertical W-shape column. If it's under compression and locally buckles, horizontal normal stresses (membrane stresses) develop and restrain the web buckling further. Because of this, more load can be applied to the web. This is where all of the Q business in AISC and beff business in AISI come from.
RE: post buckling strength