Element offsets

Hi.

If i we want to calculate on multiple layers, is there then a way of using the node/centreline geometry and then offset beam elements from these? Imagine a long one curve you would like to have two elements one above the curve and one below?

Would you have to model these to offset centrelines and then connect them with a small element in between or can you use the "Eccentricity on Beam" component? I am not really sure what it does and I can't seem to figure it out from the manual.

Thanks Rasmus

Replies to This Discussion

Permalink Reply by Karamba3D on December 3, 2012 at 6:56am

The 'Eccentricity on Beam'- and 'Eccentricity on CroSec'-components introduce a rigid connection between a beams center axis endpoints and the endpoints of the line which was used to define its geometry. You could also generate small beam pieces instead: due to their large stiffness very short beam pieces introduce numerical difficulties though.

You can also define eccentricities on cross sections in the 'CrossSectionValues.csv'-table.

Best,

Clemens

Permalink Reply by Rasmus Holst on December 3, 2012 at 12:59pm

Hi Clemens.

So you are saying that I can use these components for what I am trying? This means it is possible to define two beam elements pr. line - with different offsets of course?

Best regards Rasmus

Permalink Reply by Karamba3D on December 3, 2012 at 10:56pm

Yes. You will get the proper bending and axial stiffness; for shear the Kirchhoff Hypothesis applies.

Best,

Clemens

Permalink Reply by Rasmus Holst on December 4, 2012 at 1:52am

Thanks Clemens.
Maybe I can ask one last thing or maybe it is more of a request. When using the eccentricity component or the orientate component, the datatree structure is flattened to a list? Is it not possible to keep the initial tree structure?

Permalink Reply by Rasmus Holst on December 4, 2012 at 3:40am

Okay I was a bit quick in saying last question :).
Does it have any impact on the calculations that when offsetting straight elements along a bend curve, there will be an increasing gap between the elements the further they are offset?

I would like to show a sketch of what I mean, but I can't upload this in a reply here, but I can email it, if you want?

Thanks.

Rasmus

Permalink Reply by Karamba3D on December 4, 2012 at 4:08am

There will be a gap in the display, not in the FE-calculation: If you offset the axes of beam elements they are rigidly bound to the end-nodes of the line which was used to define them.

You can see the rigid-elements by enabling them in the BeamView: Structure Tags -> Eccentricities.

Best,

Clemens

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