topic Re: Moment Diagram in Robot Structural Analysis Forum

Moment Diagram

Michele100100 — Tue, 23 Aug 2022 14:17:57 GMT

Hello,

it seems something is not correct in Moment diagram at columns n.16, n.17 and n.61. Why there is Moment on top and is not Zero??

Below realeses in the structure and Moment Diagram on the columns:

Thanks

Re: Moment Diagram

okapawal — Tue, 23 Aug 2022 15:02:20 GMT

@Michele100100

Bending moments in columns 16 and 17 may come from torsional moment in the arc beam if you blocked Rx at both ends.

Column 61 has fixed connection to the beam 53.

Re: Moment Diagram

Michele100100 — Tue, 23 Aug 2022 15:11:18 GMT

Hello,

ok fixed at column 61 with beam 53.

For column 17, how can I solve? If I dont fix both ends, the calculation give me back an error 3060.

Thanks for your help anyway!

Re: Moment Diagram

okapawal — Tue, 23 Aug 2022 15:33:06 GMT

Share the model if you can.

Zip it and attach here.

Re: Moment Diagram

Michele100100 — Tue, 23 Aug 2022 15:47:25 GMT

Attached the model

Re: Moment Diagram

okapawal — Wed, 24 Aug 2022 11:06:00 GMT

Hi @Michele100100

The error message comes from modal analysis.

But the model is not stable. The arc is a mechanism with these releases.
Run just a self-weight load. You will see displacement in kilometers

One more hint. If you want to convert self-weight load case to masses, then you need to check "Disregard density" in modal analysis. Otherwise the self-weight mass is duplicated in modal analysis.

Alternative solution is not to convert self-weight load case to masses and leave unchecked "Disregard density".

Re: Moment Diagram

Rafacascudo — Wed, 24 Aug 2022 12:20:19 GMT

Re: Moment Diagram

Michele100100 — Wed, 24 Aug 2022 12:53:48 GMT

Thanks!

Re: Moment Diagram

Michele100100 — Wed, 24 Aug 2022 12:56:11 GMT

I tried to do that, but I have Moment in the side where Rx is Blocked.

There is any other way I could try? I have tried with partial stiffness but still having a moment on top of the column.

Thanks

Re: Moment Diagram

Michele100100 — Wed, 24 Aug 2022 12:57:11 GMT

Column 17 released, column 16 blocked

Re: Moment Diagram

okapawal — Wed, 24 Aug 2022 13:03:28 GMT

You may apply pinned release at the top of the column.

Re: Moment Diagram

Michele100100 — Wed, 24 Aug 2022 13:59:54 GMT

I tried, and I dont know why, but I could make it work only for column 17, but I still having a Moment on 16

If I trying releases at same way of 17 on column 16 I have an instability.

Re: Moment Diagram

Michele100100 — Mon, 29 Aug 2022 10:20:11 GMT

Hi @okapawal,

I was checking on that curved beam, and how you say there is a big displacement. Do you have any advise on how to solve?

Thanks