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Contributor
peter-rc
Posts: 20
Registered: ‎11-08-2012
Accepted Solution

slab deflection in column zone

681 Views, 7 Replies
01-20-2013 09:33 PM

Hi,

i get slab deflection in column zones.

i modelled my building without foundation and assigned fixed support to columns.

why i get such error? i checked every steps but i can not find,

could you pls help me

thanks

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Product Support
Artur.Kosakowski
Posts: 4,621
Registered: ‎12-17-2010

Re: slab deflection in column zone

01-21-2013 01:01 AM in reply to: peter-rc

Try to display the deformation of the whole building looking at its side. This should give you the indicate where to look for the cause. Otherwise send us your model.



Artur Kosakowski
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Contributor
peter-rc
Posts: 20
Registered: ‎11-08-2012

Re: slab deflection in column zone

01-21-2013 02:45 AM in reply to: Artur.Kosakowski

First of all, thanks for your attention.

i couldn't find any clue,here may screen view.

i also want to send you model but size is to much (with results 52mb, without results 24 mb)

 

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Distinguished Contributor
refaat
Posts: 121
Registered: ‎09-17-2012

Re: slab deflection in column zone

01-21-2013 03:21 AM in reply to: peter-rc

Dear Peter-rc

 

Kindly , take a look to  the attached capture

 

Thanks

 

Refaat

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Product Support
Artur.Kosakowski
Posts: 4,621
Registered: ‎12-17-2010

Re: slab deflection in column zone

01-21-2013 05:58 AM in reply to: peter-rc

My assumption is that this is the effect of shortening of columns at each of levels (much larger than walls) under the applied load. Such effect does not exists for gravity design by hand when you assume that columns are the supports that do not move vertically.

 

You can try to leave only one of the top slab with its supporting wall and columns (and supports at their bottoms) and check the slab deflection - this is the approach I would use for slab design.

 

You can also try to increase E of the columns and reduce their ability to 'attract' bending from slab using some elastic releases.

 

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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Contributor
peter-rc
Posts: 20
Registered: ‎11-08-2012

Re: slab deflection in column zone

01-22-2013 09:16 PM in reply to: Artur.Kosakowski

Hi Artur and Refaat,

i assigned rigit link (only Uz direction) to every column and now everything is ok..

thanks for your help

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Distinguished Contributor
refaat
Posts: 121
Registered: ‎09-17-2012

Re: slab deflection in column zone

01-23-2013 04:31 AM in reply to: peter-rc

Dear Peter-rc

 

Please , you have to take care if (you use vertical rigid link only Uz)and you have any later loads on your structure because the axial force distribution will be effective as you see in the attached capture .

 

As well , I would like to draw your attention that there is big difference between node displacement and the slab deflection . The slab deflection related to the element (slab) itself while the node displacement related to the movement between the nodes themselves.

 

Thanks

 

Refaat

 

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Contributor
peter-rc
Posts: 20
Registered: ‎11-08-2012

Re: slab deflection in column zone

01-24-2013 02:56 AM in reply to: refaat

Hi Refaat,

You are right, my column loads (axial) are false. You can see differences.(cap5-without rigit links. cap6-with rigit link)

N, M, Q and reinforcement values are wrong for columns. there is also interesting point; reactions are ture....

i will delete lateral forces, i wish i will get true axial forces..

 

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