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Re: Pushover

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> In fact, bi-linear model will pop members free suddenly when tangent modulus
>  changes at the kink from a finite value to zero.  
Speaking only for what I know about ANSYS, using a zero tangent modulus 
is usually asking for trouble with numerical instability. A good first 
start is to take the tangent modulus as about 10% of the elastic modulus 
to avoid exactly what you're talking about. If you get nervous about not 
having convergence to 4 significant figures you can do convergence 
studies from there. My own opinion is that anyone who thinks he can 
analyze real structures to an accuracy of 4 significant figures is 
dreaming.

>Huh? 
What didn't you understand? Should I be writing louder? 

> Isn't it a shortcoming of bilinear material assumption? Tangent modulus
>  has just two values unlike real world situation.  
It's the same assumption as the usual elastic/perfectly plastic limit 
analysis approach that has always been assumed for steel. You can use any 
material model you like but the effect is usually to complicate matters 
needlessly.


Christopher Wright P.E.    |"They couldn't hit an elephant at
chrisw(--nospam--at)skypoint.com        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw



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