Non-Linear manual load combination for moving load

[Anonymous]

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.

[Rafal.Gaweda · Accepted solution]

Make model temporaryly linear

Generate combinations as shown on example below:

Make model nonlinear again

[Anonymous]

Thanks, it worked

[Rafacascudo]

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

[Rafal.Gaweda]

File please.

[Rafacascudo]

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

[Rafal.Gaweda]

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)

[Rafacascudo]

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?

[Rafal.Gaweda]

Right 😞

[Euge_I]

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.

[Rafal.Gaweda]

Hi @Euge_I

Video links fixed.

[julie_liuMMRV7]

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.

[Rafacascudo]

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

[festevesBEJLD]

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

[Rafacascudo]

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 .