Round Pad Footing 2

[Bailey_SE]

Anyone know how to calculate soil pressure for a round pad footing with vertical load and overturning? I'm thinking of just converting the area to a square and using that formula.

 

[WinelandV]

Here's a document that one of the geotechs posted a very long time ago. It's very handy. Gives solutions for not only a circular footing, but also rectangular bi-axial bending footings. There's a small table in Fig. 6-14 that you may need to iterate, but it's pretty straightforward.

Enjoy!

Please note that is a "v" (as in Violin) not a "y".

 

[JoshPlumSE]

We used to do Octagon footings all the time back in the day. We always used and equivalent square. Based on area.

 

[BAretired]

The square footing makes more sense. It's easier to build and all the bars are the same length.

 

[dik]

If large... octagon is good... used them a few times... easier than bending formwork... it's harder to straighten out!

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[la belle vie]

For a circular footing, wouldn’t you just calculate P/A +/- M/S? For M, you could calculate a single resultant. S=Pi*d^3/32. Not easy to construct, but easy to analyze, no?

 

[WinelandV]

la belle vie,

That formula will work until the eccentricity is outside of the kern. After that, you have a triangular shaped soil bearing profile underneath a circular segment - which makes for messy math to get to qmax.

Please note that is a "v" (as in Violin) not a "y".

 

[JoshPlumSE]

If large... octagon is good... used them a few times... easier than bending formwork... it's harder to straighten out!

That's right. I was a young buck at the time. But, that was the reason we were given.... that Octagons were so much cheaper to construct than round footings. It allowed the contractors to re-use formwork efficiently as well.

 

[la belle vie]

Ah yes WinelandV. My brain just exploded!

 

[BigH]

For me, the Bible of elastic solutions for geotechnical Engineers is Poulos and Davis's Elastic Solutions for Soil and Rock Mechanics. It presents it all!

You can access it here:

http://www.usucger.org/PandD/complete_book.pdf

- see chapter 3 and 5 for instance.

 

[WinelandV]

BigH,

I tried the link - it returned a 404 Not Found error.

I searched the site and found the "Books" area, but when I click on the link for Elastic Sol'ns, I get redirected to a page asking if I want to join USUCGER.

Please note that is a "v" (as in Violin) not a "y".