SMALL DRIFT IN EBF UNDER IDA

[ashf]

Hi,
I have a 3D eccentric braced frame and I analyzed it using IDA,but drifts are very small in stories even at big accelerations such as 3.g!!!
Why?
Is that why analysis doesn't converge successfully?
I use steel02 material (fatigue only for brace),fiber sections and nonlinear elements and also consider post-buckling effect in braces.
To converge analysis I use the code posted by selimgunay.
What should I do?

Thank you.

[Prafullamalla]

Drift depends upon, no of stories and stiffness.for tall stories, drift are higher and allowable drift is also higher. Also, if stiffness is large, drift decreases.
Convergence is independent of the amount of drift. To check the convergence, you check the earthquake data and the last step of analysis. they should be same number if it converges.
Example if earthquake data is 1500 and, the last step of analysis is also 1500, then the analysis is converged

[ashf]

Thank you so much
Only an another question,shouldn't I use elastic element for beams and columns or it doesn't affect on result of IDA curve?

[Prafullamalla]

In beam you can use elastic element based on assumption that beam is rigid. for column its better to use element forceBeamColumn. For, simplicity, you can use element nonlinearBeamColumn for both column and beam
yes, it definately affect the drift and that means it affects IDA curve.

later on you need to consider hysteric material for reinforcing bars which considers pinching effect under cyclic loading, also column and beam joints
This is good example. I prefer this method
http://opensees.berkeley.edu/wiki/index ... ment_Frame

[ashf]

Thanks a lot.