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Thanks vesna, I tried but it still didn't converge. When I modeled the spring as linear the model works well, do you think the problem comes from the steel02 material.

Hi vesna I made a simple spring model using steel02 material subjected to a ground motion. Based on the period of the spring and the response spectrum of the ground motion I estimate the displacement of the spring and calculate the corresponding initial stiffness and yield value ( K001 & Fyield ...

Dear vesna

Thanks for your help. I understand about the syntax of a load pattern, I just don't understand why we have to do that, I erased these lines and the program still runs normally .

And in your previous post, you said that F = K*u + C*v**a

I thought the Maxwell Material is a linear spring and nonlinear dashpot in series hence F = ku = cv**alpha ? Please reply me as soon as possible. Thanks a lot.

Dear vesna Can you tell me where can I see the equations Dr. Dimitrios G. Lignos used for his Maxwell material ? I still have trouble to understand his example http://opensees.berkeley.edu/wiki/index.php/Calibration_of_Maxwell_Material. My second question is in his example, what are these codes for ...

Dear vesna

Can I send you my model through email? Thanks a lot.

Dear vesna I ran my model through a ground motion with dt = 0.02. I put Analyze 2000 steps with dt = 0.02. Then I put Analyze 1000 steps with dt 0.04. I expected to have close result between 2 running but it is not. In your example here http://opensees.berkeley.edu/wiki/index.php/Time_History_Analys...

Dear Vesna I am using the maxwell material to model my damper. I have a question regard to the parameter K, C for the damper. uniaxialMaterial Maxwell $matTag $K $C $a $L $matTag integer tag identifying material $K Elastic stiffness of linear spring (to model elastic stiffness of viscous damper) $C ...

I understand now, thanks a lot vesna

Dear vesna and fmk I am reading the "Calibration of Maxwell Material" example - http://opensees.berkeley.edu/wiki/index.php/File:Maxwell_Calibrator.tcl - and I don't understand about this code, can you explain it to me: recorder Element -file Maxwell_Calibrator/Displacement.out -time -ele ...

I have one more question vesna. I encountered the problem like this when I try to do the eigen analysis ArpackSolver::Error with _saupd info = -9999 Could not build an Arnoldi factorization.IPARAM(5) the size of the current Arnoldi factorization: is 9factorization. The user is advised to check thate...

Thanks vesna.

I also encounter the same problem like this ArpackSolver::Error with _saupd info = -9999 Could not build an Arnoldi factorization.IPARAM(5) the size of the current Arnoldi factorization: is 9factorization. The user is advised to check thatenough workspace and array storage has been allocated. Can an...

I am sorry I don't understand what you mean.

According to the Chopra book, I think the first value of the ground motion is at t=0.02, acceleration at t = 0 is zero ( does not show in the ground motion file).

I mean to get the absolute acceleration:

AAccel(t) = ReAccel(t) + GAccel (t)

However, the result I got is this:

Aaccel(t) = ReAccel(t) + GAccel (t+dt)
I just edited my previous post, hope you can understand my question now.