topic Re: ROBOT RESULTS VS ETABS in Robot Structural Analysis Forum

ROBOT RESULTS VS ETABS

muhamed12889 — Mon, 07 Jan 2019 20:32:29 GMT

Hi there,

I pulled the same analytical model from Revit, run it once at ETABS and once at RSA and defined everything exactly the same (MATERIALS, SECTIONS, LOADS ASSIGNS, RELEASES, Ix,Iy REDUCTIONS FOR SECTIONS,...)

I used a simple a load combination (1.4D + 1.6L) to compare results on the main frame in building

and here is the moment diagram results for each and I don't know the reason why the moment diagram from RSA looks like this (please see screenshots).

What I am thinking of it's support definition but it's same hinged support at ETABS and RSA.

I am designing the isolated footings based on normal force only so I don't need to make it fixed support and don't need to show any moments on foundations.

Will appreciate any feedback and advises about this issue.

Thanks & best regards,

Mo.

Re: ROBOT RESULTS VS ETABS

muhamed12889 — Wed, 09 Jan 2019 07:22:09 GMT

Any feedback on this matter, which one is considered more accurate.

Re: ROBOT RESULTS VS ETABS

Artur.Kosakowski — Wed, 09 Jan 2019 08:38:52 GMT

Hi @muhamed12889

I'd try to create a simple frame at the beginning in both programs and then compare the results first so that I could easier find the reason for the difference. If there is none then I'd add the attributes (ans short cantilevers) one by one to determine when the results start to differ.

I'm afraid that without having both programs and your models it is impossible to tell what is different in them.

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

Re: ROBOT RESULTS VS ETABS

muhamed12889 — Wed, 09 Jan 2019 20:21:06 GMT

Thanks for your feedback, I will try as you said on simple frame and compare results.

Will be happy to hear any feedback from ETABS users who moved to RSA.

Thanks & best regards,

Mo.

Re: ROBOT RESULTS VS ETABS

napooil — Thu, 10 Jan 2019 15:04:33 GMT

Can you attach both model file? please

Re: ROBOT RESULTS VS ETABS

muhamed12889 — Thu, 10 Jan 2019 15:30:44 GMT

SURE. HERE YOU ARE ETABS V17 & ROBOT 2019.

Re: ROBOT RESULTS VS ETABS

muhamed12889 — Sat, 12 Jan 2019 10:51:21 GMT

@napooil Hi there,

Did you check the models?

Thanks.

Re: ROBOT RESULTS VS ETABS

khimpitou — Sat, 12 Jan 2019 17:31:16 GMT

In RSA, try to Select all elements (Column and Beam) then intersect and re analyse.

Re: ROBOT RESULTS VS ETABS

muhamed12889 — Sat, 12 Jan 2019 20:02:53 GMT

I tried what you said but there was no difference.

Re: ROBOT RESULTS VS ETABS

muhamed12889 — Mon, 14 Jan 2019 21:05:30 GMT

I built the model from scratch on ETABS and the moment diagram was fine and looks like the moment diagram from RSA with different values.

Thank you all.

Re: ROBOT RESULTS VS ETABS

acmprojetos — Thu, 17 Jan 2019 19:58:21 GMT

So we can conclude that Revit (analytical model) and the ETABS do not talk right?

Re: ROBOT RESULTS VS ETABS

muhamed12889 — Sat, 19 Jan 2019 12:19:20 GMT

What I concluded that it is not one man's job.

When starting a new project:

Someone will build his own structural model from scratch for analysis whether it's ETABS or RSA.

Someone else will start his own architectural Revit model.

Someone else will start his own structural Revit model.

I think that way will avoid time consuming editing and adjusting and watching the differences between models.

If you build your model from scratch on ETABS and build another model from scratch on RSA without linking or importing from any other software you will find that the analysis results will be almost the same and to be honest I still didn't compare results in case of seismic and wind load types included but I will try it later.