Can push over analysis capture the failure of a simple col.?

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Moochul Shin
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Joined: Mon May 14, 2007 8:05 pm
Location: URBANA, IL

Can push over analysis capture the failure of a simple col.?

Post by Moochul Shin »

Hello!

I built a simple column which consists of five nonlinearBeamcolumn elements.
And then I analyzed the column using push over test to draw shear force at the support and relative displacement at the top.
At the first time, as I increased the maximum displacement, the analysis failed to converge and then gave me a result of force displacement diagram which had certain line to drop suddenly.
At that point I thought that the push over analysis could know when the column collapses. All procedure I did was using the unconfined concrete model.

But I used several confined concrete model, then the analysis seems endless analysis. Why is that?

So my guestion is " Can 'push over' analysis recognize the failure of the system such as a cantilever beam or column.

Thank you very much
silvia
Posts: 3909
Joined: Tue Jan 11, 2005 7:44 am
Location: Degenkolb Engineers
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Post by silvia »

yes it can.
however......
if you use the nonlinearBeamcolumn element, you really only need a single element with about 5 integration points to model a single column. More elements lead to numerical instabilities and failures to converge.
The beamWithHinges, a modification to the forced-based nonlinearBeamColumn element, is supposed to capture a strength-degrading system more accurately, but it seems you are doing okey with the nonlinear bc element.
to find out why a column with unconfined concrete fails more rapidly than one with confined concrete, you might want to look at mander's work on that.
Silvia Mazzoni, PhD
Structural Consultant
Degenkolb Engineers
235 Montgomery Street, Suite 500
San Francisco, CA. 94104
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