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sendSelf and recvSelf are not implemented correctly for the elements and materials you are using.

Which elements and materials are in your model?

TwoNodeLink

There is no difference between "horizontal" and "vertical" periods. Periods are periods.

Define mass and stiffness in the vertical direction and you will get an eigenvalue that corresponds to vibration in the vertical direction.

Try using the latest version of OpenSees (3.5.0)

I don't know all the details, but check Table 5.1 and Figure 5.5 of the Haukaas and ADK PEER report shown on the wiki page.

Which material? There's a few variations/implementations of BoucWen

Can you try with Python 3.11?

1. Which version of Python are you using?
2. How did you install openseespy?

What's the problem?

Please give more details.

This post might help: https://portwooddigital.com/2023/11/15/ ... sh-shells/

You are using truss elements with 3 DOF/node in a 2D model, so the rotational stiffnesses are all zero.

https://portwooddigital.com/2021/09/19/ ... ing-nodes/

The chordRotation recorder gives the basic deformations of the element - axial deformation plus nodal rotations relative to the element chord.

You should check your Concrete02 input parameters for lambda, ft, and Ets

https://portwooddigital.com/2021/08/22/ ... oncrete02/