Robot Structural Analysis

## Robot Structural Analysis

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Posts: 183
Registered: ‎12-06-2011
Message 11 of 15 (141 Views)

# Re: Foundation design for ductile wall

05-14-2013 08:11 AM in reply to: t.sautier

@ Sautier

ductile walls : this means you are designing a project in a seismic area ? if you do so, it is recommended to have stiff lower level system : this means raft, spread or continuous footing but tied up together by ground beams in both direction

Yes, it  is in a seismic area and the spread footings shall be tied together with ground beams in both directions

uniform loadings for the design of the footing : it is a shear wall -> it means you will get bending moment in the reaction then the load cannot be uniform, it is trapezoidal loadings

Yes it is a shear wall and the reaction will be trapezoidal, but the short length of the wall "could" mean that an average uniform load could be assumed i.e load signs would not change so as to negate each other (stand to be corrected).  The structure is braced primarily by these ductile walls.  There is an off-centre elevator shaft which actually introduces torsion into the response, but that could be the subject of another discussion.

i would separate the models for the buildings and for the foundations (you can get some api in this forum that take the reaction of a model in order to convert it as loads for another).

I would be very much interested in this if it exists!!

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Posts: 183
Registered: ‎12-06-2011
Message 12 of 15 (135 Views)

# Re: Foundation design for ductile wall

05-14-2013 08:18 AM in reply to: Artur.Kosakowski

My approach would be to use the RC Spread Footing module in the Continuous Footing mode and depending on load distribution I would either define N as the average or maximal value of reactions under the wall.

Artur, with a 1000x200mm wall won't this approach give me a very wide (so as to satisfy allowable bearing capacities) 1000mm long spread footing?

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Posts: 129
Registered: ‎12-14-2012
Message 13 of 15 (135 Views)

# Re: Foundation design for ductile wall

05-14-2013 08:45 AM in reply to: stroxy

"Yes it is a shear wall and the reaction will be trapezoidal, but the short length of the wall "could" mean that an average uniform load could be assumed i.e load signs would not change so as to negate each other (stand to be corrected).  The structure is braced primarily by these ductile walls.  There is an off-centre elevator shaft which actually introduces torsion into the response, but that could be the subject of another discussion."

To design your footing you shall take into account the excentricity due to the moment. For exempla use the Meyerhof formula :

Q = N / ((L - 2 x e) * B) where e is M/N. you will apply something uniform to to a reduced area.

Otherwise you could exceed the soil bearing capacity.

"I would be very much interested in this if it exists!!"

A fabulous topic where rafal and arthur have put the links to all the api developped in this forum in order to make our daylives less miserable or much more easier

http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Only-reaction-for-new-model-API/m-p/3659242/...

TS

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Registered: ‎12-17-2010
Message 14 of 15 (114 Views)

# Re: Foundation design for ductile wall

05-14-2013 11:48 PM in reply to: stroxy

stroxy wrote:

My approach would be to use the RC Spread Footing module in the Continuous Footing mode and depending on load distribution I would either define N as the average or maximal value of reactions under the wall.

Artur, with a 1000x200mm wall won't this approach give me a very wide (so as to satisfy allowable bearing capacities) 1000mm long spread footing?

I think you may want to compare the results you have for the above approach and for a spread footing with the 1000x200mm column and then decide which one to choose.

Artur Kosakowski
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Posts: 183
Registered: ‎12-06-2011
Message 15 of 15 (110 Views)

# Re: Foundation design for ductile wall

05-15-2013 12:02 AM in reply to: Artur.Kosakowski

So to do the comparison with the spread footing under a 200x1000mm column, I am going to save the substructure comprising the columns and nodal supports. Then export reduced forces from base of wall panels into excel and apply them as loads to the saved substructure, and design pad as footings.  Theoretically should work.

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