Type of support definition

[JF-PTA]

Hi,

When creating a spring nodal support the support label appears on every other tabs (linear and planar).
Should this be happening?

When I check the support table I can't see a distintion between nodal, linear and planar supports and their respective units. How can I control the type of supports used on the model?

Thanks

[Artur.Kosakowski]

You  may create different labels (support names) for nodal, linear and planar supports.

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.

[JF-PTA]

But, as in my case, if you pick up an existing model, what is the way to find out what type of supports are created?

Along with that, by mistake, I think I've assigned a nodal spring support as a linear support to panel edges, ending up with double stiffness on corners between edges and respective peak reaction values (double of average). This should not be allowed by the program, right?

Thanks

[AhmedZA]

there is only one  way to control the type of supports   as shown below

[JF-PTA]

Thanks for replies.

As I've seen so far, after creating the support, there is no way of knowing what type it is unless the labels indicate it, right?

You can't check it by units (they appear in the table as kN/m for nodal, linear and planar) or any other way, is it?

[AhmedZA]

Is that what you mean?

[Pawel.Pulak]

Some additional info related to:

1. the availability of different types of elastic supports on Nodal, Linear, Planar tabs of the Supports dialogue
2. the "hierarchy" of supports and overwriting surface supports by linear and nodal supports and overwriting linear supports by nodal supports

See this video (with additional audio explanations and comments):

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Regards,

[JF-PTA]

Hi,

Here is an example of the problem I've found.

Consider a concrete slab model with 10x10x2.5m supported on 4 sides.

I've created 3 different models:

On the left with nodal spring supports of kz=100 MN/m each.
On the midle with linear spring supports of kz=100 MN/m/m each.
On the right with nodal spring supports of kz=100 MN/m applied as linear on the edges (wich can happen by mistake because the program allows it). These changes the reactions bescause, I think, Robot considers twice the stiffness on the corners between edges.

The question is, should Robot allow to assign nodal springs as linear springs (by mistake)?
This comes along with the fact that, besides label, it seems to be no other way of controling if a support is nodal, linear or planar.

Is this what is happening?

Thanks

[Pawel.Pulak · Accepted solution]

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@JF-PTA wrote:

Here is an example of the problem I've found.

Consider a concrete slab model with 10x10x2.5m supported on 4 sides.

I've created 3 different models:

On the left with nodal spring supports of kz=100 MN/m each.
On the midle with linear spring supports of kz=100 MN/m/m each.
On the right with nodal spring supports of kz=100 MN/m applied as linear on the edges (wich can happen by mistake because the program allows it). These changes the reactions bescause, I think, Robot considers twice the stiffness on the corners between edges.

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In both models with supports applied to edges (the model in the middle and on the right) the stiffness in corner nodes is obtained by adding the stiffnes corresponding to both edges meeting in this corner but

1/  for the model in the middle the tributary length for corner nodes is half of the tributary length for internal nodes so the sum results in the correct value

2/ for the model on the right the stiffness is the same in all nodes so the sum in corner nodes results in doubled stiffness

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@JF-PTA wrote:

The question is, should Robot allow to assign nodal springs as linear springs (by mistake)?

This comes along with the fact that, besides label, it seems to be no other way of controling if a support is nodal, linear or planar.

Is this what is happening?

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It can be checked whether the correct support label is assigned to edges verifying whether "Constant elastic coef. at support nodes" check-box is not active in the definition of the label. I have shown and discussed it in the video linked in my previous post.

The improvement request  was registered to report verification warning when nodal elastic supports are assigned to edges, panels or faces.

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If this post answers your question please click the "Accept as Solution" button. It will help everyone to find answer more quickly!

Regards,

[JF-PTA]

Thanks