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CO046 Error when modelling OWSJ with web members defined as "truss".

I'm trying to analyze an existing OWSJ using S-Frame 2022. I've modelled the top and bottom chords as the "beam" member type and the webs as the "truss" member type. When I go to run the joist, the solver produces an error code CO046 - "unremovable unstable dof..". I'm wondering if I can get some help to what is going on. Maybe I should actually be defining the web members as the "beam" type since they are technically welded to the double angles?

Thanks,

Deana

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Andres Chavez

Hello Deana,

Thanks for posting in the Altair Products forum. My name is Andrés, and I work at Altair's Technical Support. I'll be more than happy to assist.

We appreciate the elaboration, and sending your screenshots along. From the looks of it, it is possible that the OWSJ is unstable due to the lack of restraints in some of the supports. If we take a closer look at the supports, we can see that the OWSJ is not restrained from rotating about the X-axis in three out of four supports. In a similar fashion, there are no constraints for rotation about the Y-axis in any of the supports, so depending on the loading applied, the structure may become unstable at different points, as it may rotate about X or Y in most of the supports. Additionally, S-FRAME is reporting that several nodes are unstable in DoF 2 (Degree of Freedom 2), which is the translation about the Y-axis. Let's not forget that DoFs 1, 2, and 3 are for translation about the X, Y, and Z axes respectively, and DoFs 4, 5, and 6 are for rotation about the X, Y, and Z axes respectively.

If you'd like to investigate deeper, you could open the ERR file in Notepad that S-FRAME's solver generates after running an analysis. This file is located in the same folder as your model, and it will contain the full list of FYI, Warning, and Error messages that the solver found when running the analysis. You could then check each message code in S-FRAME's Solver Diagnostic Messages document to have a little bit more insight into each one of them.

We'd love to take a closer look at your model to provide a more accurate answer, so feel free to attach it to your reply using the 'Add attachments' button under the text box if you deem it necessary. We hope this preliminary assessment is helpful, and we look forward to hearing from you again.

Kind regards,

Andrés Chávez Burgos

AEC Solutions Engineer

Deana David

Thank you for the prompt reply.

I have tried changing the support types without making them completely fixed, as I don't want to create a moment reaction at these locations. But doesn't seen to resolve the error.

I tried attaching the TEL file but your attachments don't support that type of file?

Deana David

I have some other general S-Frame questions I'd like to ask and am wondering if there's an email address I can get instead of posting all my questions here?

Thanks,

Deana

Andres Chavez

I have some other general S-Frame questions I'd like to ask and am wondering if there's an email address I can get instead of posting all my questions here?

Thanks,

Deana

Hello Deana,

Thank you for the prompt reply. We are sorry to read that the model cannot be attached to the forums. We can suggest, for this model and for your subsequent general S-FRAME questions, to send an email to sframe-support@altair.com to create a ticket in our separate technical support platform, Service Now. You may attach any file to your email and it will be received on our end when the ticket in Service Now is automatically created.

Feel free to send two separate emails, though; one for the item discussed in this post, with your TEL file, and another one with your S-FRAME general questions. We will be glad to attend both cases separately, to keep the information in order. We can continue our discussion over there.

Kind regards,

Andrés Chávez Burgos

AEC Solutions Engineer