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I have a bridge model with compression only supports
Is it possible to have combinations including a moving load case??
It runs the combination ,but I get N/A results
Rafael Medeiros
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In fact it kind of "run" the combination.I would expect it to run all the components just like a ordinary moving load case.But it starts the iterative process ,but no mention of components and it finishes after the 5th iteration.
Rafael Medeiros
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Try to convert positions of the vehicle into simple load cases and then use them for definition of combinations.
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Artur Kosakowski
So is it not possible, then??
I have 52 "normal" load combinations and 2 moving load case with 184 components each.
So it would be 52x(2x184)=19136 load combinations.EAch combination takes 90 seconds to be solved. so it would like 478 hours or almost 20 days in a core i7 ,16gb ram computer.
Is there an easier/faster way??
Please ,see(attached) the error I got after more than 10 hours running the model(combinations and moving cases separetely),with only 5 load cases to go
Erro de execução means execution error
Rafael Medeiros
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First of all regardless of the way you create combinations (as automatic components as in your original question or manually) each of them has to be calculated separately as the superposition of results does not apply to nonlinear model. For large number of cases/combinations you may select the multi-threaded solver which should be considerably faster than others. In addition you may also ask yourself if you need to have 184 positions of the vehicle - perhaps you could set larger step with some indicated characteristic points instead
As the automatic generation of components of combinations is not available for nonlinear analysis you may use the combination wizard for the generation of manual combinations.
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Artur Kosakowski
MInd that after generating the combinations you may set the original moving load cases as well as the simple load cases with the definitions of the vehicle positions as auxiliary.
Artur Kosakowski
Thx Artur,
Yes I´m using multithreaded solver, auxiliary cases. Bridge (stayed Arch) has 150m span with two 7.5m cantilivers on each side ,so it´s 165m long.Vehicle step is 1m and I also ask to calculate at polyline points ,so that´s the 184 components.
Is there a way to apply temperature loads to a slab without a FE mesh? That would cut the case solution time to 30secs
What about that error in the log??
Rafael Medeiros
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Is there a way to apply temperature loads to a slab without a FE mesh? That would cut the case solution time to 30secs
No, there isn't. My assumption is that the temperature load causes slow convergence of the analysis (longer time of the analysis). Try the following test first:
- select the combination with slow convergence and calculate the results for it
- change the parameters of the nonlinear analysis setting only one increment of load and calculate the same combinations
- compare results
- if successful apply to all other combinations
You may also reduce the relative tolerances from 1e-4 to e.g. 1e-3 to reduce the numbers of iterations necessary to finish each step of iterations.
What about that error in the log??
I need the file to investigate what is its cause.
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Artur Kosakowski
Thx, great help changing load increment number 5 to 1 . Results are the same with 1/3 of the time.
How to use the combination wizard as Robot doesn´t have the brazilian codes
Rafael Medeiros
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The wizard needs the regulation file therefore you would need to either create your own one or use one already available and then edit the load factors. You can also try this one:
http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Editing-load-cases-in-excel-API/td-p/3320573
Do you know where I can find the rules that describe generation of combinations according to the Brazilian code? I will add this request to the wish list for the next versions of Robot.
If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.
Artur Kosakowski
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