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Thanks for helping m, but I still have problem. I used a loop to get the frequencies, but only the first step's frequencies are calculated and for others the following message is there: "BandArpack Solver::Error in dgbtrf_ Warning FrequencyAlgo::Solve Current Step<>_ the eigen S0E failed in sol...

Hi there,
I want to have the natural modes' frequencies in each time step in the nonlinear dynamic analysis. What I have to do? (the first 2 modes are enough)
cheers,

Yes. Of course. As I said it doesn't show nonlinear behavior! Evenif I set the earthquake factor a large number like 500!!!!! It continues to behave elastically untill it collapses.

Dear all, (especially Silvia) I've used elastic sections and performed static analysis first but the behavior is totally elastic. Can you take a look on my script to see whetherthere is something wrong or not. It would be so helpful for me. Here it is: # 3 storey building with 3 bays in x-direction ...

Hi, I have another question. When we say rayleigh damping doesn't consider truss and zerolength elements does it mean the stifness of these elements oare not considered in the total stiffness matrix?!

Hi there, I'm doing my master's project by help of opensees. It is about the effect of Tuned mass damper on the earthquake induced response of 3-D steel structures. I've built both elastic and nonlinear models. There is no problem with elastic model, the results seem to be correct. But the nonlinear...