topic Re: Planar support in Robot Structural Analysis Forum

Planar support

davidVGKKE — Mon, 10 Oct 2016 10:26:19 GMT

I have created a planar support but it raised some questions:

1 - Why when I hit ok on Building soils - Calculation of K coeficiente window KZ value is not transfered to support definition window as it was supposed to do according to robot help? (Since K value is not transfered i have to convert from kip/ft3 to kN/m and type it in the field on support definition window )

2 - Why is KZ expressed as kiP/ft3 on building soils and as KN/m on support definition window?

3 - Why the units doesn't change to international units since I set it up to international unit system on Jobs preferences window?

4 - Does the KZ generated by FE thickness, whose unit is kN/m3, the same KZ seen in support definition window, whose unit is kN/m? Do they have to be equal?

Re: Planar support

Artur.Kosakowski — Mon, 10 Oct 2016 10:44:33 GMT

1 - Why when I hit ok on Building soils - Calculation of K coeficiente window KZ value is not transfered to support definition window as it was supposed to do according to robot help? (Since K value is not transfered i have to convert from kip/ft3 to kN/m and type it in the field on support definition window )

This works for a spread footing mode only. For other two modes you need to copy the value via clipboard.

2 - Why is KZ expressed as kiP/ft3 on building soils and as KN/m on support definition window?

and

3 - Why the units doesn't change to international units since I set it up to international unit system on Jobs preferences window?

Try these steps:

4 - Does the KZ generated by FE thickness, whose unit is kN/m3, the same KZ seen in support definition window, whose unit is kN/m? Do they have to be equal?

They are the same kN/m3

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Re: Planar support

davidVGKKE — Mon, 10 Oct 2016 12:54:35 GMT

Thanks Artur for you reply.

How can the both KZ be equal if they have different units (kN/m3 and kN/m) ?

Re: Planar support

Artur.Kosakowski — Mon, 10 Oct 2016 12:59:03 GMT

1/m2 and kN/m = kN/m3 (see the yellow marked parts of the screen capture I attached in my previous answer).

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Re: Planar support

davidVGKKE — Mon, 10 Oct 2016 13:51:09 GMT

Artur I'm talking about the KZ generate by thickness that comes in kN/m3 and KZ generate ou typed on support definition. Ok if I divide (kN/m3)/(1/m2) I'll get kN/m, but why does Robot do it? Is it just a better way to work with this coeficient?

If so, then, I can call both of them as elastic foundation coeficient?

Re: Planar support

Artur.Kosakowski — Mon, 10 Oct 2016 13:58:41 GMT

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.

Re: Planar support

davidVGKKE — Mon, 10 Oct 2016 14:34:23 GMT

Do you mean the number 3 is missing in kN/m3 on support definition window?

Re: Planar support

Artur.Kosakowski — Mon, 10 Oct 2016 14:38:43 GMT

No, what I mean is that you should combine the 'general units for planar supports 1/m2 displayed in the top right corner with the units for particular field (kN/m) which stands for kN/m3 in total

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Re: Planar support

davidVGKKE — Mon, 10 Oct 2016 14:59:33 GMT

Could you give me an example of combination I should do?

Are the numbers shown on the windows (10996,13 kN/m3; 1000 kN/m; 1000 kN/m) such combination, if so, what kind of combinations was done?)

Re: Planar support

Artur.Kosakowski — Mon, 10 Oct 2016 15:07:09 GMT

I just made the screen captures with random values (my mistake as I assumed we are discussing units) and they should be all the same.

So if you have 1000 kN/m3 for elastic ground in the thickness dialog and then you enter 1000 in the UZ field of the planar support definition they are the same as when you multiply units [1/m2] * [kN/m] you have 1000 kN/m3

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