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saaddk
Posts: 14
Registered: ‎04-23-2012

Re: How to support a structure in only one direction

05-10-2012 01:08 AM in reply to: tony.ridley

Hi Thx for the great answer :smileyhappy:. I want to restrain the whole bottom surface of the footplate against movement in -z  direction. When i do this, IT DOESENT WORK, it restrains all movements in the z- direction.the reason i want to restrain the whole bottom surface is because i want it to look that the footplate is "laying" on  a concrete block.) please check attached

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Artur.Kosakowski
Posts: 4,545
Registered: ‎12-17-2010

Re: How to support a structure in only one direction

05-10-2012 01:13 AM in reply to: saaddk

As you define the direction of the possible uplift you should set UZ+ instead of UZ-.

 

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Artur Kosakowski
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jo2ny
Posts: 82
Registered: ‎02-07-2012

Re: How to support a structure in only one direction

02-27-2013 01:29 AM in reply to: saaddk

Hi,

 

I'm having also trouble with this kind of supports.

In my model (a relatively simple rectangular box shaped structure) I have several supports set to Uplift UZ+ and after the calculations I stil get some posive and some negative reactions in these kind of supports.

Even if I set the direction wrong, they should have had the same sign or zero.

Right?

Any ideas why?

 

I mention that these are reactions values of a basic seismic load case.

 

Thanks

 

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Artur.Kosakowski
Posts: 4,545
Registered: ‎12-17-2010

Re: How to support a structure in only one direction

02-27-2013 02:11 AM in reply to: jo2ny
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jo2ny
Posts: 82
Registered: ‎02-07-2012

Re: How to support a structure in only one direction

02-27-2013 04:02 AM in reply to: Artur.Kosakowski
I read all the topics you indicated. Found out the explanation why dynamic modal analysis cannot be combinet with a non-linear structure. Therefore As a workaround I eliminated modal analysis, and the seismic load cases. I replaced the seismic loads with static horizontal loads (equivalent values) at the top of my 1 level structure. Now, without the modal cases I still get both + and - signed values in Uplift+ UZ supports. Actualy it seems that nothing is changed. Any ideas why? I did this test on a 2D simple frame , and it works as it should. I get one signed values, and zero. But my real model doesn't behave the same way and I don't know why.
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Artur.Kosakowski
Posts: 4,545
Registered: ‎12-17-2010

Re: How to support a structure in only one direction

02-27-2013 04:07 AM in reply to: jo2ny

I need the rtd file to look at.



Artur Kosakowski
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jo2ny
Posts: 82
Registered: ‎02-07-2012

Re: How to support a structure in only one direction

02-27-2013 04:38 AM in reply to: Artur.Kosakowski

I attached the model.

Thanks for helping.

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Artur.Kosakowski
Posts: 4,545
Registered: ‎12-17-2010

Re: How to support a structure in only one direction

02-27-2013 05:22 AM in reply to: jo2ny

The analysis for cases 6,7 and 10 is divergent so the results are incorrect. Try to create combinations of these load cases with the vertical (stabilizing) ones as exists in reality and check the values of reactions again.

 

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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jo2ny
Posts: 82
Registered: ‎02-07-2012

Re: How to support a structure in only one direction

02-27-2013 05:29 AM in reply to: Artur.Kosakowski

Ok, you're saying that if the combinations I will create (using the load cases you mentioned) will be convergent, then I can count on the results as being correct?

 

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Artur.Kosakowski
Posts: 4,545
Registered: ‎12-17-2010

Re: How to support a structure in only one direction

02-27-2013 05:33 AM in reply to: jo2ny

Yes, this is what I mean. In real life there is no wind without e.g. selfweight isn'it? :smileywink:



Artur Kosakowski
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