Modelling different elasto-plastic behaviour in tension and compression

[alda30]

Hi,

I'm trying to model a fibre reinforced concrete beam with different stiffness and stress-strain curve in tension and compression.
How should I implement this model?
Can I simply add the compression with negative values as below: (example numbers)
*plastic
-1200,-1
-100,-0.1
20,0.1
120,1

Thanks in advance for your help and assistance.

Alex

[mkraska]

I don't think that this approach will work, because the stress-strain curve is defined in terms of equivalent stress and equivalent strain, which both can't be negative.

[mkraska]

Theoretically, a non-symmetric stress-strain curve (yield curve) could be obtained by using kinematic hardening with non-zero initial back stress. This, however, would not affect stiffness.

[mkraska]

How about a combination of compression-only and linear elastic material? Essentially, you copy each element and assign the second material to the copies.