Wall foundations

[stroxy]

Is it possible in determining foundations for walls with low length/thickness ratios, to use the reduced results for panels at the base as a nodal force on an equivalent sized column?

[Artur.Kosakowski]

Do you have the axial force and out of the wall plane bending or the axial force and bi-directional bending situation?

[stroxy]

Mostly axial force and in plane bending.  Ductile walls with length to thickness ratio of wall = 5.  Walls are about 200mm thick and between 900 and 1200 long.  Out of plane bending is minimal

[Artur.Kosakowski]

Personally I would try the following approach:

1. Estimation of the size (with the focus of the width at this stage) of the foundation using the RC Spread Footing module with the 'equivalent' column

2. Definition of rectangular beam (of such width) on elastic ground under the wall in the model

3. Design with RC Continuous footing module

4. Comparison of the main reinforcement in the direction of the wall and decision what to decide on

5. Use of the reinforcement from the point one for the perpendicular direction.

Other ideas 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.

[stroxy · Accepted solution]

Sounds good!! Will give it a try

[stroxy]

Do you have the axial force and out of the wall plane bending or the axial force and bi-directional bending situation?

Artur

I was wondering why you asked the above question.

Is it correct that the strip foundation module only considers out of plane moments on the wall

What are your concerns with using only the equivalent support approach

[Artur.Kosakowski]

If there is no in plane bending you may just try to use the RC Spread Footing nodule in the continuous footing mode (vertical laod + out of the plane bending for unit length of  the spread footing)

[stroxy]

Personally I would try the following approach:

1. Estimation of the size (with the focus of the width at this stage) of the foundation using the RC Spread Footing module with the 'equivalent' column

2. Definition of rectangular beam (of such width) on elastic ground under the wall in the model

3. Design with RC Continuous footing module

4. Comparison of the main reinforcement in the direction of the wall and decision what to decide on

5. Use of the reinforcement from the point one for the perpendicular direction.

Seeing that I have in-plane bending, and my walls are generally between 900 and 1200mm long, Is it possible to design the beam on elastic ground longer than the wall, say 2000mm long to limit the width of the foundation (to satisfy allowable bearing pressure).

Also what are your concerns on just using the "equivalent" column approach with reduced wall forces?

[Artur.Kosakowski]

Seeing that I have in-plane bending, and my walls are generally between 900 and 1200mm long, Is it possible to design the beam on elastic ground longer than the wall, say 2000mm long to limit the width of the foundation (to satisfy allowable bearing pressure).

You may define a bar element with elastic soil in the model that is longer than a wall.

Also what are your concerns on just using the "equivalent" column approach with reduced wall forces?

Personally I'm not sure how accurate this approach is therefore I would like to compare it with the reinforcement calculated for 'bending moments' in the beam on elastic soil.

[stroxy]

Span P1.Left support Insufficient amount of additional reinforcement for upper struts

Hi Artur

What could be the reason for the above error in the coninuous footing design?

[Artur.Kosakowski]

Do you have any point (column) support? That indicates some problem with excessive shear.

[stroxy]

Yes I do.  I added a column to the continuous footing.  Will see if I can isolate it with a pad.

Thanks