## Modified Ibarra-Medina-Krawinkler Deterioration Model

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mehdikia2519
Posts: 39
Joined: Sun Apr 19, 2009 12:03 am
Location: Iran

### Modified Ibarra-Medina-Krawinkler Deterioration Model

dear frank

Convergence problem is happened during incremental dynamic analysis when the Modified Ibarra-Medina-Krawinkler Deterioration Model (Bilin Material) is used . it is worthy to note this problem cannot be solved by utilizing the smaller time steps .
It would be your kind if you help me with this problem

brag006
Posts: 173
Joined: Wed Feb 15, 2012 1:26 pm
Location: University of Auckland

### Re: Modified Ibarra-Medina-Krawinkler Deterioration Model

try changing analysis parameters. Implement a loop which changes parameters if one fails. There are a few examples which use these loops. Increase the number of iterations

Posts: 15
Joined: Sat May 25, 2013 11:44 am

### Re: Modified Ibarra-Medina-Krawinkler Deterioration Model

remove IDA analysis from your code.
Use eigen command to obtain the period of the structure After Static analysis. Does it work?

mehdikia2519
Posts: 39
Joined: Sun Apr 19, 2009 12:03 am
Location: Iran

### Re: Modified Ibarra-Medina-Krawinkler Deterioration Model

dear hnaderi and barg006
thanks for your attehtion
both suggested teqniques were applied befor , but nothing achived . it is noting , convergence problems remove when other type of model is used .

Posts: 15
Joined: Sat May 25, 2013 11:44 am

### Re: Modified Ibarra-Medina-Krawinkler Deterioration Model

I think problems occur when you want to calculate the damping of structure with eigenvalue command before Dynamic analysis.
this means that your model is destroyed by the gravity loads. Check your model (units, mass, sections, elements, loads, Constraints, ...)
Maybe there is a problem in the definition of Bilin material in your model. (increase the stiffness of rotational springs)
if the model is correct, you should calculate rayleigh damping factors (alpha, beta) manually. Do not use the eigen command.

I've seen this problem in several different cases for dynamic analysis. (Ibarra-Medina-Krawinkler Model, BeamColumnJoint element, Joint2D element and ...)
Totally, i think this type of modeling is not proper for Dynamic analysis (It seems unrealistic), Especially if someone wants to consider damage accumulation in structure and elements.

hshoar
Posts: 26
Joined: Wed Sep 12, 2012 5:45 am
Location: Sience and Research branch of IAU
Contact:

### Re: Modified Ibarra-Medina-Krawinkler Deterioration Model

Hi,

Here is Dr. Mckenna's suggestion in analysis failure! :

fmk: start by changing the elements to be elastic beam columns. if that fails your nodes, elements or boundary conditions are messed up.
if it works change the section to be elastic for the nonlinear beam columns. if that fails check your beam definitions.
if that works change the materials to be elastic. if it fails your section is wrong.
if that works your materials are incorrectly defined. look at the parameters or consider switching material types.

Good Luck!

xiell
Posts: 15
Joined: Thu Nov 14, 2013 6:22 pm
Location: Tsinghua University

### Re: Modified Ibarra-Medina-Krawinkler Deterioration Model

I have also done some research on this model, I think it is not due to the accumulation stuff. This model really works well in all static analysis, only not fit for dynamic analysis.