problem with IDA results

[shjelvan]

Hello
i want to calculate R,Cd and omega_0 parameters of a Steel Moment Frame according to FEMA-P695
i used IK-model with concentrate plasticity(plastic hinges) for beams elements according to Pushover_concentrated example and i used dispBeamColumn with fiber section and steel02 material for columns elements.

i also have linear model in CSI SAP and i checked the period and forces in linear region with my opensees model and they were the same.

even the pushover curve seems to be logical and i got omega_0=3 for my frame after static nonlinear analysis.
http://imgh.us/Pushover_Curve.png
But my problem is with IDA where the relationship between max interstory drift and record factor is linear in every record even when the factor is very high! i check the plastic hinges and columns elements and it seems that every thing is OK but i cant find reason why this happen.
http://imgh.us/IDA_1.png
any idea that where the problem is !?
sorry that i cant explain the problem so good and the code is huge and i cant put all of it here but if anyone need it i will mail it for him.

[fmk]

what is the b in the steel02

[shjelvan]

i try both ,the same problem
#Unit n/cm2
1)uniaxialMaterial Steel02 $secID 28800 20000000 0.02 15.0 0.925 0.15;
2)uniaxialMaterial Steel02 $secID 28800 20000000 0.0001 15.0 0.925 0.15;
seriously i dont know this is a proper material (with these parameters) for modeling columns in a moment frame or not.

[fmk]

steel02 is a more reliable material than the IK models and the results will be very similar if the IK models are calibrated correctly and there is not too many cycles for degredation. in fact you might try replacing the IK model with a Hysteretic model and have a look at the IDAs (just in case the issue is with the IK model)

[shjelvan]

thank you for help but just last question.
i used Ik model because i can easily calculate every parameter even parameters of degredation according to Lignos and Krawinkler (2011).But I have no experimental data for calibration of steel02 or hysteretic material and i have no idea how to calculate their parameters specially degredation .for example i see some hystersis for steel02 but i dont know which one is proper for columns with p-m interaction or suitable values for damage in hystertic material. is there any references that can help ?

[fmk]

i mean to just just use the monotonic curve (fig 1) and run without degredation and look at the response .. the hysteretic parameters should be obvious so try that first.