Load Definition - kN/m2?

[heetap]

Hello,

Is there any way I can apply a udl in kN/m2? As I have characteristic design loads with those units and I am finding it difficult to find any load definition that will allow me to apply it; the uniform load is obviously in kN/m. This is for a curved roof structure, modelled as a series of straight I-beams. It's all quite simple for now, but frustrating...

Thanks.

[heetap]

Ok, so I've tried a cladding and applied a uniform planar load, and it seems to be...ok. However, I don't seem to be getting any results (e.g. deflections, shear, etc.) from the snow load case, even though it has the highest magnitude. Doesn't sound reasonable... I would have thought there would be at least some sort of result.

Cheers.

[Artur.Kosakowski]

Please check if you have the same settings as discussed in http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Claddings-and-geometrical-objects/m-p/306900...

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.

[heetap]

Thanks, I have tried that. Doesn't seem to work.

I have just tried remodelling, and I've realised when I apply dead, wind or snow load in any direction to the 'top' claddings the loads are displayed but they produce no results. Only the self-weight of the structure produces reactions on those claddings. Wind load applied to the side claddings (columns) produces results fine though.

Is there some kind of cladding-to-beam connection I seem to be missing here? If there is such a thing?

Sorry, I'm still at the intermediate stages of learning with Robot. Thanks for all your help.

[Artur.Kosakowski]

When a cladding is defined at the same level as its supporting beams are then any surface load applied to this cladding should be transferred to the beams. From your description I would say that the beams and the claddings have to be defined at slightly different levels. If this is the case you can try to correct this situation in the way described here (adjust to plane):

http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Detailed-Correction/m-p/3079956/highlight/tr...

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.

[heetap]

I've basically added claddings to the same nodes that the beams are defined. I'm still having the same problem. Is there any other way I can add a distributed load to these beams?

Thanks.

[Artur.Kosakowski]

Could you make a screen capture that shows the part of the structure with the cladding that makes troubles  (or even better send the model) please?

[AlexDT]

Could it have anything to do with the "Model > Trapezoidal and triangular method = Analyze/Ignore?" in the Inspector Dialog Box?

I thought that if an element has this parameter on ignore, it wont be seen by claddings.

Right?

[Artur.Kosakowski]

Correct.

[heetap]

It's the whole model that's affected. I tried attaching the model, but .rtd files aren't allowed...?

So attached are some screenshots. COMBI is dead, snow and wind. The displacement results for the wind is due to the x-direction loading only, hence, z-direction wind load does nothing. Loading in z-direction does not produce results for any load case, as evidenced by the snow load screenshot. Thanks very much.

Edit: Alex - thanks for your input. However, all beams are under 'analyse'.

[Artur.Kosakowski · Accepted solution]

As stated in Help (see http://docs.autodesk.com/RSA/2012/ENU/filesROBOT/GUID-FA1CD831-C70E-4407-A85D-3FFCA2C8DB8-307.htm)

which is not the case for the roof in your model. I think that the easiest is to convert the cladding into a 'standard' panel with very small thickness assigned (to reduce the influence of its stiffness) and transfer load via its mesh. Otherwise you would nee to to apply load directly to rafters using one of the available bar load types.

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.

[heetap]

Artur,

Thanks very much for your help. I've converted the claddings into steel panels with small thickness and I'm now getting results!

[heetap]

Hi,

As you mentioned, the panel needs to be very thin so that it's stiffness does not affect the results. However, when I make it very thin (0.001 mm), I obtain huge displacements. When it is 1 mm thick, the displacements are absolutely fine. Do you think I should keep it at 1 mm thick? The load from the panel is obviously affecting the results, but I have already got a value from the actual roofing material that will be utilised.

Is there any way I can set the panel parameters so that it is the same as the roof cladding used in my design already?

Thanks.

[Artur.Kosakowski]

IMHO if you assume that you disregard roof as a structural part of your model (cladding approach) you should use the small value of thickness and ignore any results obtained for the panel itself. Otherwise assign the material and thickness of the 'real' roof.

[tony.ridley]

or just give it a material with zero density