hysteretic material cyclic behavior

ca493 · Post by **ca493** » Wed Sep 17, 2008 10:40 am

Hello,

My hysteretic material behaves fine when I subject it to a static load. Its tension and compression trilinear parameters match what I entered when defining the material, of course. However, when I subject it to a cyclic load (ie EQ) it acts unusual.

Every time it crosses the force = 0 axis, it looks like it changes stiffness and doesnt match at all the backbone curve that I specified. I gave its pinching paramaters 1 and 1. It damages parameters 0 and 0. And its unloading stiffness a default 0.

Here is a link to a picture of the plot if my description was unclear:
http://picasaweb.google.com/cariyara/Un ... 4024120210

any suggestions?

silvia · Post by **silvia** » Wed Sep 17, 2008 11:55 am

that's the material behavior. the reloading stiffness is dependent on the maximum defor in that direction.
you can do a cyclic static analysis to see the behavior.

ca493 · Post by **ca493** » Wed Sep 17, 2008 7:04 pm

Thank you for your help!

Is there a way to change it such that the reloading stiffness is equal to its elastic stiffness?

silvia · Post by **silvia** » Thu Sep 18, 2008 5:31 am

no, look at other materials...

pejman_opensees · Post by **pejman_opensees** » Thu Sep 18, 2008 10:00 am

I have the same problem. There should ne a way outta this. At least more documentation regarding hysteretic material is needed I suppose.

silvia · Post by **silvia** » Thu Sep 18, 2008 1:56 pm

not really. i have even put in a bunch of curves describing the effects of the parameters.
hysteretic material is pretty simple and straightforward.
it is not based on any model, it gives you hysteretic response.
you can create your own material based on hysteretic. have you looked at the pinching material?
the hardening material might be what you want/need.