topic Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature in Robot Structural Analysis Forum

Discrepancy in Self-Weight Calculation in RSA vs. Literature

ugur_yavan_61 — Mon, 24 Jun 2024 16:04:38 GMT

Hello everyone,

I am currently working on a project and encountered a discrepancy in the self-weight calculation of RSA . The self-weight computed by RSA is higher than what is reported in literature studies. I also manually calculated the weight using the length and unit density, and my results matched those in the literature, but not the RSA results.

Has anyone experienced similar issues or can explain why RSA's calculations might be higher than expected?

RSA calculation:

Python Calculation:

Literature:

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

Stephane.kapetanovic — Mon, 24 Jun 2024 18:08:36 GMT

Hi @ugur_yavan_61

The best thing would be for you to share your project. Zip it first.

Best regards

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

ugur_yavan_61 — Tue, 25 Jun 2024 08:45:31 GMT

Here is the RSA project and one of many studies that find the results differently https://doi.org/10.1061/(ASCE)0733-9445(1992)118:5(1233)

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

Stephane.kapetanovic — Tue, 25 Jun 2024 07:51:58 GMT

your link returns an "oops" message

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

ugur_yavan_61 — Tue, 25 Jun 2024 08:46:40 GMT

It works when you copy and paste it to the navigation bar. Interestingly directly clicking is not working. There must be something wrong with forum website I did not understand.

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

Stephane.kapetanovic — Tue, 25 Jun 2024 08:50:46 GMT

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

ugur_yavan_61 — Thu, 27 Jun 2024 09:47:55 GMT

If you dont click the link and copy paste it to the navigation bar it works. And also it is not that important to reach the paper since I shared the results found in the paper.

If you multiply the areas with length and unit of density, you will find same result with paper however the RSA giving higher amount for same structure.

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

Simau — Thu, 27 Jun 2024 11:44:56 GMT

@ugur_yavan_61

There is no RSA model in your link.

As said by @Stephane.kapetanovic please zip and share your model

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

ugur_yavan_61 — Mon, 01 Jul 2024 08:06:31 GMT

I did as you said. Could you try running this file ?

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

Stephane.kapetanovic — Mon, 01 Jul 2024 09:18:27 GMT

hi @ugur_yavan_61

the difference (5620/5734=0.980...) seems to correspond to gravity, are you sure of your comparison, of the densities and sections taken into account in your example, a mathematical simplification?

Best Regards

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

ugur_yavan_61 — Mon, 01 Jul 2024 16:27:11 GMT

I double checked everything. All the parameter are same except the calculated weight.

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

Simau — Mon, 01 Jul 2024 17:29:06 GMT

@ugur_yavan_61

Maybe these kind of intersections are counted twice.

Try to remove them from the value displayed by Robot

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

Stephane.kapetanovic — Tue, 02 Jul 2024 07:53:55 GMT

HI @ugur_yavan_61

Could you comment on this table and tell us what evidence you have in relation to your verifications?

can you give us the value of the density you include in your calculations?

↑ the sections seem to be the same ↓

Without a comparative list, I can't check for myself.

Best Regards

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

ugur_yavan_61 — Tue, 02 Jul 2024 07:57:05 GMT

Here is the original structure and corresponding parameters from paper:

And here is my python results:

By the way, all of the displacement and stress results matches for two model except the weight.

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

Stephane.kapetanovic — Fri, 05 Jul 2024 17:09:28 GMT

hi @ugur_yavan_61

if all lengths and cross-sections are identical, do you agree that density

is not equals to

As Explain, the difference (5620/5734=0.980 ... 5734/5620=1.02) seems to correspond to gravity !

Best Regards

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

Stephane.kapetanovic — Tue, 02 Jul 2024 08:23:18 GMT

it's a mathematical simplification in your example. the true value is the one calculated by Robot

Re: Discrepancy in Self-Weight Calculation in RSA vs. Literature

ugur_yavan_61 — Thu, 08 Aug 2024 13:11:52 GMT

Thank you for answer.

I wish you a good day.