Resultant outside the middle third of a footing
Resultant outside the middle third of a footing
(OP)
I have a residential job where the footings were not placed too accurately. Is there any reason that I cant just find the location of the load resultant and assume that it aligns with the centroid of a triangular soil bearing pressure wedge with a max pressure less than my allowable soil bearing pressure? See attached pic.
Thanks.
Thanks.






RE: Resultant outside the middle third of a footing
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Resultant outside the middle third of a footing
I guess you have the same issue even if you keep it within the middle third of a footing. In my case we are simply not using the entire footing with the remainder acting as a counterweight to pull the resultant inwards a slight amount.
RE: Resultant outside the middle third of a footing
A) Usually only interested in average settlement.
B) I've very little confidence in this, or anything, being the correct soil stress profile anyhow.
C) Maybe the counterweight bit cracks in negative flexure and you open up a vector for rebar corrosion. Unlikely though.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Resultant outside the middle third of a footing
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Resultant outside the middle third of a footing
I've certainly justified a resultant outside the kern in the same way you've described before.
RE: Resultant outside the middle third of a footing
RE: Resultant outside the middle third of a footing
Don't know that it's really disallowed anywhere either. The very first section of the Foundation chapter in the SERM has an equation for calculating max pressure when you're outside the kern and the pressure distribution looks exactly like what you're doing.
RE: Resultant outside the middle third of a footing
Mike McCann, PE, SE (WA)
RE: Resultant outside the middle third of a footing
DaveAtkins
RE: Resultant outside the middle third of a footing
RE: Resultant outside the middle third of a footing
Not that it has really changed much, all we have now is two checks to make for the foundation. Where I am it is always the SLS seeming to govern design anyway.
RE: Resultant outside the middle third of a footing
RE: Resultant outside the middle third of a footing