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Active Contributor
WASSIMSAID1507
Posts: 44
Registered: ‎11-26-2008

R.C. foundation under R.C. wall in RSA

1657 Views, 11 Replies
11-10-2011 05:57 AM

Dear Sir,

 

I need to automatically design R.C. foundation supporting R.C. shear wall in a building which has been modeled using the RSA 2012. The shear wall base edge is pinned (linear support).

is there a way to design automatically  the R.C. foundation under the shear wall as we made for the R.C. columns?

 or we must manually enter the reduced forces of the shear wall in the R.C. foundation module?

 

Your help is very appreciated. 

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Artur.Kosakowski
Posts: 5,076
Registered: ‎12-17-2010

Re: R.C. foundation under R.C. wall in RSA

11-10-2011 06:28 AM in reply to: WASSIMSAID1507

You can try to use the approach shown on the attached picture.

 

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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Active Contributor
WASSIMSAID1507
Posts: 44
Registered: ‎11-26-2008

Re: R.C. foundation under R.C. wall in RSA

11-10-2011 06:47 AM in reply to: Artur.Kosakowski

It is a safe solution for wall with normal load.

but what can we do if we have moment as for for shear wall in the building?

(reduced moments due to seismic loads for example)

 

regards,

 

Wassim

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Artur.Kosakowski
Posts: 5,076
Registered: ‎12-17-2010

Re: R.C. foundation under R.C. wall in RSA

11-10-2011 07:27 AM in reply to: WASSIMSAID1507

I would adopt the same approach but after examining the values of reactions I would select one of nodes close to the ends of the wall (larger values of the vertical reactions due to in-plane moments). Of course this is when you want to have the same width and reinforcement along the entire foundation. Otherwise I would make the design selecting number of nodes along the wall adjusting the L values so that they correspond to each of the segment I intend to design.

 

Another option is to design the foundation against a group of loads (can be used to have the same foundation for several columns as well) by means of the grouping option. In such case the values of reaction from each of the imported nodes will be used in the design process. Mind that the values of imported reactions should be modified based on the distance of the neighboring nodes (unless the mesh size is exactly 1m and the side nodes are not selected :smileyhappy:)

 

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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Active Contributor
WASSIMSAID1507
Posts: 44
Registered: ‎11-26-2008

Re: R.C. foundation under R.C. wall in RSA

11-10-2011 08:05 AM in reply to: Artur.Kosakowski

Dear Artur,

 

If I want to design the RC wall with the same footing width and depth.

The moment can produce compression in one edge and uplift in the other.

 Is there a way to design this type of footing simply or we must then input the reduced loads of the panels?

 

thank you.

 

Wassim

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Artur.Kosakowski
Posts: 5,076
Registered: ‎12-17-2010

Re: R.C. foundation under R.C. wall in RSA

11-10-2011 08:09 AM in reply to: WASSIMSAID1507

My understanding is that the reduced moment is what actually caused  vertical reactions along a wall to differ. I think the approach I described in my previous answer should be just what you need. Of course any other ideas from the user's of the forum are welcomed.

 

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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Active Contributor
WASSIMSAID1507
Posts: 44
Registered: ‎11-26-2008

Re: R.C. foundation under R.C. wall in RSA

11-10-2011 08:14 AM in reply to: Artur.Kosakowski

OK Artur,

 

Thank you.

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New Member
watsongd
Posts: 2
Registered: ‎11-16-2011

Re: R.C. foundation under R.C. wall in RSA

11-16-2011 01:18 PM in reply to: Artur.Kosakowski

Hello Artur,

Why could you not use a horizontal shell member with elastic supports to suit ground conditions with pin connection to elimnate moments?

Geoff 

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Artur.Kosakowski
Posts: 5,076
Registered: ‎12-17-2010

Re: R.C. foundation under R.C. wall in RSA

11-17-2011 12:41 AM in reply to: watsongd

I'm sorry but I'm not sure if I understand you correctly.  As far as I understand you want to replace pinned supports defined at the bottom edge of the panel (wall) with the horizontal panel on elastic ground. If yes the in-plane bending will be still there and to avoid out of plane bending you would need to define linear release at the bottom edge of the wall. Anyway if you create a foundation under the wall as the horizontal panel you can calculate reinforcement using the RC Slab design module but mind that no shear (punching) verification will be done.



Artur Kosakowski
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New Member
watsongd
Posts: 2
Registered: ‎11-16-2011

Re: R.C. foundation under R.C. wall in RSA

11-17-2011 01:09 AM in reply to: Artur.Kosakowski

Thanks Artur,

I have used this method for retaining walls and have checked shear by hand, of course with retaining walls there is no need usually to introduce the pin at slab wall junction.

Geoff 

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