Silo in Revit+Robot

[Dzianis.Hk]

Hi everyone!

What is the best workflow modeling a silo with the release of project documentation? Will be convenient to model it in Revit and export to Robot for calculation as an ordinary building? Or use Inventor is better way to do it? I am very interested in a similar experience and any advice...

Thanks!

[Dzianis.Hk]

What function should be used for time history analisys in this case and how to handle with the results of it for subsequent steel design? Is anywere some tutorial/sample on this topic?

[Rafal.Gaweda]

What function should be used for time history analisys in this case and how to handle with the results of it for subsequent steel design? Is anywere some tutorial/sample on this topic?

There is no such example but I will try to describe what you need and have to do.

1. You need to have  \ create THA function corresponding to your spectrum \ earthquake

2. Create load case in which you will apply Imposed Displacement load to supports. Depending on THA function you have, correct load type should be set - acceleration \ displacement \ velocity

3. Create THA case, set function to this case , use HHT method of Newmark Acceleration, set other data for calculations

4. After analysis look at THA results and create simple load cases from time step(s) (Component) you want to consider in combinations

5. Generate combinations

Please look also here : http://forums.autodesk.com/t5/Robot-Structural-Analysis/Time-History-units-and-methods/m-p/4858486#M...

[Rafal.Gaweda]

End else, when I try to define manual non-linear load combinations, I recive error report in any case. What could be the reason and the solution?

---

Workaround:

- make model temporaryly linear (remove tension only attributes from bars)

- generate Automatic Code combinations

- convert ganerated combinations (for example from Comninations table) to manual ones

- set tension only attributes back

Model with combinations attached

[Dzianis.Hk]

Thank you very much, Rafal!

[Dzianis.Hk]

I did the following: set load case #13 for Imposed displacement and added Imposed displasement to supports

Set THA as shown below

But the resultes are zero(

Could you please tell, what I did wrong and why the resultes are 0?

Link to latest model is here https://www.dropbox.com/s/o62ragjzhjk2rnq/Silo2.zip

[Dzianis.Hk]

And another strange thing in this model :

Load case:

Reactions:

I removed this load case and have re-defined it again - has no effect.

With similar load cases in this model is ok.

[Rafal.Gaweda]

And another strange thing in this model :

Something is wrong in contour load definition

See movie below with the way of correction:

(Not looked yet at THA in your model)

[Rafal.Gaweda]

IN case of geting nonconvergence of this case please set Newton Raphson method this way:

[Dzianis.Hk]

Thank you for the responses and tips!!

I just found why the resultes were zero. It should be made so:

[Dzianis.Hk]

But how to define maximum amplitude of ground acceleration 2m/sec2 correct? Is it correct as on the pictures below:

In this case for acceleration 2m/sec2 and masses ~1400 kN, Fx forces in THA for pillars is about 2400 kH, My is about 600 kNm. 

To convert the load of grain (hidrostatic) to masses I defined auxiliary load case (#5) with vertical equivalent distributed load on silo wall and converted it to masses with coeff 0.8.

[Rafal.Gaweda]

Your THA function resembles spectrogram but this function shlould be more like accelerogram

See example below , this example function you can find in Robot CFG folder :

Another approach came to our minds, much simpler, no need to have THA function, maybe enough for you:

- create cases in the order as written below

1. create dummy case with sw + load in direction X to activate some bracings working while the model is loaded in this direction

2. create modal case

3. create seismic case only for direction X

4. create dummy case with sw + load in direction Y to activate some bracings working while the model is loaded in this direction

5. create modal case

6. create seismic case only for direction Y

create combinations (do not include in them dummy cases described in points 1 4)

etc

[Dzianis.Hk]

Thank you very much! It is very helpful.

Only question is why in this case for siesmic Y direction (load case #20) CQC comb some X-braces are still compressed. Whereas for siesmic X direction (load case #17) all X-braces are under tension.

        

Could you please take a look to the model: https://www.dropbox.com/s/2t1hyvn46mzve5r/Silo3.zip

[Rafal.Gaweda]

Unfortunately this this unwanted effect.

[Dzianis.Hk]

I defined main mode for Seismic load case according to max mass % in Modal analysis

 

Now the resultes look better 😃

Now I can't understand why for load comb, which includs Seismic load case gaphically the following resultes are obtained

  

But in the forces table all values are N/A

 

[Rafal.Gaweda]

Special internal filter is run for tension \ compression only elements in table.
Not for diagrams.

[Dzianis.Hk]

Is there a way to take values of tension forces as shown on this diagram for further steel design? because now in steel design Zero forces are taken into account

[Rafal.Gaweda]

Send me your the latest model.

[Dzianis.Hk]

Link to the latest model https://www.dropbox.com/s/md3ligexgsza9du/Silo4.zip

[Rafal.Gaweda]

Bad luck:-(
For this type of combination (in fact it is linear combination of nonlinear and seismic case \ combination) results are not visible in tables, design.
I will register it for correction.