Bearing Pressure Determination w/eccentric loads 1

[BadgerPE]

Hey all,

Sorry in advance if this is a simple question but my brain isn't working too well during this holiday week.

The situation I have is a PEMB column sitting on a pier which will be poured monolithically within a 14' tall frost wall with uneven fill. The interior of the wall will be filled to about 13.5' and tie into the 7" RC floor to resist OT. The outside of the wall will only be filled to 4' leaving 10' exposed. Due to the uneven fill heights and an 8k rack load on the interior slab, I feel as though I should check the footing for bearing type failure due to eccentric loads. I have attached a quick sketch to illustrate what I am looking at.

What is the best way to go about determining the bearing pressure applied to the soil to ensure that the bearing capacity is not exceeded?

 

[msquared48]

If I understand correctly, the column is in the wall which is restraining fill. The column is seeing a 56K vertical load, and the wall is seeing the lateral soil pressure due to the backfill AND a surcharge due to the 8K rack load. The column has a spread footing that is integral with a strip footing of lesser width for the wall.

If this is true, I would design the column just for the vertical load, and the wall to take the soil pressure and surcharge load.

Otherwise, please enlighten us further...

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[BadgerPE]

You got it Mike!

So when I determine the size of spread footing, based upon bearing capacity, needed for the column just use the 56k vertical load and disregard the soil load?

 

[delagina]

i actually thought the question was how to check soil bearing pressure

P/A + Mc/I

if that's the question, LOL, you'll hear a lot of senior guys here to get the help of a structural engineer.

 

[msquared48]

delagina:

Read my motto...

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[BadgerPE]

Sorry for the simple/stupid question. I was confused because I was trying to solve the bearing pressure using the equations for a cantiliver retaining wall instead of one where the wall is pinned to prevent rotation.

 

[msquared48]

Crackerjack:

Don't ever apologize in this forum for asking a structural engineering question. That's what we are here for.

We all have our moments...

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

Agree with Mike. You have no net moment at the base of the column that is transferred to the footing, so there is no need to consider moment-induced bending in the footing, which is what would cause a bearing pressure increase over part of the footing area.

 

[paddingtongreen]

It looks as though the Column sits on the wall, if so the individual footing seems unnecessary. Even at 45 degrees, the load would distribute over 28 feet of the wall.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[BadgerPE]

Ron,

I was thinking that eccentricity caused by the fill being 10' higher on the inside than the outside would cause bending in the footing and therefore an increase in bearing pressure on the inside of the footing.