help-can't obtain strength degradation

Jfoyian · Post by **Jfoyian** » Sun May 03, 2009 10:07 pm

Hello,
I want to do pushover analysis (displacement based) on a displacement based beam column element, but I cant get any strenght degradation. I'm not using linear transformation (using corotational or Pdelta), and I'm pushing the column to high enough displacements but no matter what I do, the force keeps increasing. I also tried using nonlinear beam column element but it gives similar response, i.e, no strenght loss. I wonder what I'm doing wrong and what I should be doing instead.

silvia · Post by **silvia** » Mon May 04, 2009 6:33 am

it's a well-design section.
are you using stee02? that always has a positive slope, so it's hard to lose strength.
try hysteretic for steel.

Jfoyian · Post by **Jfoyian** » Tue May 05, 2009 9:51 am

yes I was using steel02. Hysteretic material for steel works, but I though the degradation in concrete itself would also cause the force to drop down after some time. I'm still confused why concrete doesnt affect the backbone in that sense.

silvia · Post by **silvia** » Tue May 05, 2009 10:04 am

because you have enough steel to control the response.