topic Re: Non-Linear manual load combination for moving load in Robot Structural Analysis Forum

Non-Linear manual load combination for moving load

Anonymous — Tue, 07 Oct 2014 06:12:24 GMT

Hello,

I want to analyze the effect of a crane on a beam. The crane is modelled as travelling load. I have tension bar in my structure, which forces a non-linear analysis. When I run the analysis, Robot does not calculate results for load combinations which I have defined manually. In Analysis type diagram, I have hooked off the option for “Auxiliary case”, but after I run the analysis it is hooked on again. If I make a load combination without the travelling load, Robot can calculate forces; however it skips load combination when I have moving load in the combination.

In advance, thank you for your help.

Re: Non-Linear manual load combination for moving load

Rafal.Gaweda — Tue, 04 Dec 2018 20:54:34 GMT

Make model temporaryly linear

Generate combinations as shown on example below:

Make model nonlinear again

Re: Non-Linear manual load combination for moving load

Anonymous — Tue, 07 Oct 2014 08:58:41 GMT

Thanks, it worked

Re: Non-Linear manual load combination for moving load

Rafacascudo — Wed, 05 Nov 2014 15:44:40 GMT

I´m not able to make it work. Followed the instructions. Combinations are created. No problems when Running the linear model.

When I turn it into non-linear (linear releases Rx and uz+ uplift) ,problems arise.

- In analysis parameters , everything remains "static linear"

- Ok , it runs as it is really non-linear , but as soon as it begins solving it , the loads due to my vehiche vanishes from the combinations!!!!!

http://screencast.com/t/iZpGUsRO

The only way I managed it to work was generate load cases from each moving load component and when create the combinations manually in excel

Re: Non-Linear manual load combination for moving load

Rafal.Gaweda — Thu, 06 Nov 2014 07:14:52 GMT

File please.

Re: Non-Linear manual load combination for moving load

Rafacascudo — Thu, 06 Nov 2014 11:20:33 GMT

Hi Rafal ,

I´m sending the linear model with already generated combinations.Works perfectly!

When I introduce a nonlinear element like unidirectional support or unidirectional linear release , the 6 concentrated loads due to the vehicle vanish from the generated combinations cases

Re: Non-Linear manual load combination for moving load

Rafal.Gaweda — Tue, 04 Dec 2018 20:58:03 GMT

In case nonlinear calculations you have to have real loads in real cases so do it this way (or create combinations manually with converted components)

Re: Non-Linear manual load combination for moving load

Rafacascudo — Thu, 06 Nov 2014 13:07:16 GMT

thx ,

so that´s the workaround I have done before.Create load cases from moving load components.

And that that 1st tip , make it linear, generate combination, make it nonlinear is really not working,right?

Re: Non-Linear manual load combination for moving load

Rafal.Gaweda — Thu, 06 Nov 2014 13:01:57 GMT

Right 😞

Re: Non-Linear manual load combination for moving load

Euge_I — Tue, 04 Dec 2018 20:47:21 GMT

I'm trying to do a P-Delta analysis with moving loads, but I have no combinations. I have arrived to these link, but I'm not able to see the video: it sais that "the ID for this Screencast is invalid." May you describe a little what to do? Or to re-upload the video?

Sorry for the inconvenience.

Re: Non-Linear manual load combination for moving load

Rafal.Gaweda — Wed, 05 Dec 2018 09:44:13 GMT

Hi @Euge_I

Video links fixed.

Re: Non-Linear manual load combination for moving load

julie_liuMMRV7 — Wed, 07 Aug 2024 13:07:03 GMT

Hi, I have the same problem with moving loads and the load combinations which are not running. I can't see the example, could you please resend the link. Also, what do you mean by making the model linear ? I have supports which enable an uplift so I have automatically non linear cases.

Re: Non-Linear manual load combination for moving load

Rafacascudo — Wed, 07 Aug 2024 21:10:41 GMT

what I understood from Rafal´s answer on 2014 is that combinations that have moving loads do not work if the model is nonlinear.

As I answered previously ,You will have to create single load cases from moving load components and make combinations one by one

Re: Non-Linear manual load combination for moving load

festevesBEJLD — Thu, 13 Nov 2025 10:29:35 GMT

Is there a way to make an envelope load/combination with the moving load automatic cases so we can use it on design?

Re: Non-Linear manual load combination for moving load

Rafacascudo — Thu, 13 Nov 2025 12:31:26 GMT

Design will consider only single load cases or load combinations . Combinations which include moving loads will be considered only if they are linear.

Envelopes are not considered .