Error in the calculation of global imperfections

Product Support
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1

Good morning, how are you?

I am currently modeling a 3-story reinforced concrete building. I want to consider the effect of Global Imperfections on the building with respect to the X and Y directions. The model considers eccentricities for the beams (Members) and Surface elements (Surface) to be able to align the structural elements. Additionally, I considered cracking and creep effects in the structure, in the "Consider Structure Modification" option.

The slabs were modeled with "Hinges" so that they do not contribute stiffness to horizontal displacement and only the columns or pillars, walls, and beams bear the horizontal forces.

I considered the Global Imperfections with the "Initial Swap Via Table" option. However, when I analyze the building, I get the following results:

  1. When I see the displacement results of the imperfections, I get this:

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image801×577 126 KB

A distortion of the results can be seen at some points that have displacements greater than those entered in "Initial Swap Via Table." This is observed in the 4 cases of imperfections that are in the model.

  1. I get an "Error and Warning" message that the software itself indicates:

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I understand that the distortion mentioned before is the direct consequence of this error message.

My questions are:

  1. Is it possible to model the building with the considerations I introduced in the model? Is it possible to combine the option with "Initial Swap Via Table" with eccentricities of beams or columns (Members) and Surfaces? Or what causes the issue I have with the visualization of the incongruent displacements?

  2. In the Building Model Add-On, for each floor, I indicated the following:

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In case I indicate in the "Floor Diaphragms" option that it is "Semi_Rigid" and "Rigid," when I analyze the building, I get "Errors and Warnings" messages. I would like to know what causes these messages to occur? Is it possible to combine the "Semi-Rigid" or "Rigid" option with the eccentricities of the "Members" or "Surfaces" elements (mainly in the slabs of each level)?

I attach the model I made in RFEM6 so you can evaluate it if possible. Perhaps I entered the model parameters incorrectly.

Project1_Earthquake.rf6 (1.3 MB)

I hope you can help me with the questions and doubts I have about handling the Software.

Best regards

3

Hello Pablo,

  1. It should be possible, but I couldn't figure out why the calculation doesn't converge. I'm going to discuss this further with the team.
    In the meantime, you can either remove the eccentricities or use another form of imperfections (e.g., local imperfections).

  2. The Building Model add-on is intended for creating a simplified 2D model. The option "None | Original stiffness" actually means sticking with the 3D model. You need to decide whether to commit to the simplification approach and choose either "rigid" or "semi-rigid," or not. Mixing "None" with "(semi-)rigid" doesn't work. The same applies to eccentricities. This level of detailed modeling is not intended for the Building Model add-on.

If you have any further questions, don't hesitate to ask.

Best regards,
Matthias

4

Hello Matthias:
Thank you very much for your help and for the explanation you gave me. Regarding the two points:

  1. I removed the eccentricities of the elements and it works correctly. I don't see the distortions I had at the beginning. However, as you said, it should work with the eccentricities of the elements. Please, could you tell me later if there is a way to fix that problem.
    Also, one last question, is there another way to do "Global Imperfections"? What would those methods be?

  2. I understand that the Building Model add-on does not take into account a more detailed level.

Best regards,
Pablo Enrique

5

Hello Pablo,

you can create member sets of your columns and then apply equivalent local imperfections to the member sets. I tested it in a test file. For the local imperfections I obtained the same results as for global. Please have a look at the file.

Test Imperfection global vs local.rf6 (1,0 MB)

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image1061×984 194 KB

If you have any further questions, don't hesitate to ask.

Best regards,
Matthias

6

Thank you very much for the information. I will try it. Any questions I have, I will ask.

Best regards,
Pablo Enrique

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