Non Linear Push over analysis in Etabs - Solver settings and solution scheme in Non Linear parameter

[sriharsha.g]

Hi, I am doing a Non linear push over analysis in etabs for 6 storey steel building. Every time, I run the analysis, I am getting different curves even though there is no change in the model and I am not able to understand which one is correct. I am using the following solver settings and non linear parameters. Correct me If i am wrong.

Advanced sapfire options: Advanced solver type
Solution Scheme: Event to event only
Maximum total steps: 0
Maximum Null steps: 0
Event Lumping Tolerance: 0.03
Maximum events per step: 300
Stop when max events per step exceeds: No
Min. Event step size: 0.000001
Max Null events per step: 10
Kindly check and help me

 

[JoshPlumSE]

Honestly, I don't think we have enough information to help a great deal. I would personally prefer the iterative Event to Event solution scheme. But, I don't know that I can give much more advice based on what little information we have.

Some general suggestions for investigating weird behavior on a model:
a) Start with a smaller version of the model and see if you can get the behavior you expect. Then add on to it a little at a time. This can be a long process, but it definitely helps you to figure out if there is a portion of your model that is causing the problem.

b) You might even try this on a different computer. I've seen cases (with a different analysis program) where there was a corruption to some program settings that was causing a memory error that led to the program behaving erratically.

c) Make sure a static, linear analysis of your model is working properly before you add in all the non-linearity. Sort of the same concept as item (a) above. If you full model works great in a linear static analysis, then add in one family of a few hinges at a time to see when the bad behavior begins.

 

[sriharsha.g]

Thank you,

I have already ran the static analysis with standard solver in etabs to check for instability but it doesnt have any. I will start with floor by floor as you suggested