eccentrically loaded single foundation
eccentrically loaded single foundation
(OP)
I have an eccentrically loaded single foundation (sketch bellow). A column is on the edge of foundation since there is an existing structure right next to it. I want to calculate contact pressures under a foundation in point 1, 2, 3 and 4. I havent done this in years and I cant find my equations...Any help?
thanks.
thanks.






RE: eccentrically loaded single foundation
Brian C Potter, PE
Simple Supports - Back at it again with the engineering blog.
RE: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
What do you guys suggest I do here? i have new structure next to existing. New single foundations next to existing foundation are eccentrically loaded. Should I connect single foundations with foundation beam (i dont know what is a proper expression in English)?
is there another/better way?
RE: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
connecting eccentrically loaded foundation with centrically single foundation with a RC beam seems to be a way...
RE: eccentrically loaded single foundation
His recommendation is the way you should be doing it.
RE: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
However keep in mind that it will not be truly pinned, nor will it be truly fixed, but rather somewhere in between. Your joint detailing will play a huge part in which assumption is more correct. The foundation beam should be designed for some moment transfer from the column, however the column and frame structure above should be designed as if the base were pinned.
RE: eccentrically loaded single foundation
1) Having the footing closer to the load generally makes for a cheaper arrangement.
2) In my experience, it's rare that you'd be able pull the footing so far back that its zone of settlement influence wouldn't still impact the existing building anyhow.
3) In pulling the footing back, leverage increases the load delivered to the footing. So, in a non-linear manner, the extra load is kind of undoing what was accomplished by pulling the footing back in the first place. At least this would be the case for the modest setbacks that I'd typically expect to see.
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: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
I was thinking about connecting single foundations with strap footings in all directions. So the eccentricity can be transfered through strap footing.
RE: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
RE: eccentrically loaded single foundation
You should model the south continuous footing (the one against the existing building) as a footing supported on soil.
If you can get this to work with a slight eccentricity (you should be able to do that since it appears to be only one story), then just use isolated footings on the north column line and you're done.
If you can't get that continuous footing to work, add straps going north-south to the north column line footings. The purpose of that strap is to counteract the eccentricity of the south column footing with the weight of the strap. You can find a good reference for this in the Structural Engineering Reference Manual that a lot of people use for studying for the SE exam. Technically you're required to leave a gap between the strap and the soil. I often see some sort of compressible material there (and sometimes soil...).
The east-west continuous footing at the north column line you show isn't really necessary if you keep the isolated footings at that column line.
RE: eccentrically loaded single foundation
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: eccentrically loaded single foundation
Though I highly recommend buying it. I use it once or twice a month.
It's a very well put together text.
RE: eccentrically loaded single foundation