asdeasoft.net

Dear STKO team
I'm working in SSI of a two storey building. I'm just studying the modal analysis, but when I run the model the structure doesn't stay attached at the soil.
what will be the problem?

Dear user,

There were 2 mistakes:

1. You have many overlapping constraints. In this case, the Transformation handler may not work. So you need the Penalty. In your case, 1.0e14 is a good penalty number.
   However, in order to use the Penalty and not the default (transformation) for the Eigen, you need a "fake" analysis command just before the Eigen, where you set up the settings that you want. This "fake" analysis, should have NO STEPS (not a real analysis, just used to set up the "ingredients" for the Eigen command), and should not use the "wipeAnalysis", otherwise all those ingredients will be lost.
2. Your beam-to-solid interaction was wrong. It was connecting only 1 column to 1 foundation, and erroneously to a node from the soil. This interaction should use all the column-bottom-nodes as masters (retained nodes), and the top faces of the foundations as slaves (constrained nodes).

Additionally, I don't think you need EDOF in X and Y for the foundation sides. EDOF means periodicity. And you use periodicity conditions for the soil faces because it extends "indefinitely". But this is not true for the foundations. You already model the full size of the foundation.

Here is the working file. Moreover, consider making the mesh finer. In your original file you used 1 subdivision per geometric entity. This is sometimes fine for beams/trusses (only when elastic, same section, etc...) but not for shells or solid elements.

thanks for your advice, I really appreciate it.
I solve my problem. This forum is the best!!!!

Glad we could help and that you enjoy the forum! Goodl uck with your model