Eccentric wall footer
Eccentric wall footer
(OP)
Hi Everyone
I am designing a rear addition in dc where the foundation will be built on the property line... We planned to build an L footer which we have done on several project in the past however the reviewer says the footer doesn't account for eccentricity... based on a 2500 Psf soil pressure we would need to offset the 8" cmu 4" from the party line with a 42" footer and build the addition with wood framing instead of cmu all the way up in order to keep the q max under the allowable soil pressure... my question is do you guys know any solutions that would allow me to buld to the property line with no offset either with cmu or wood framing
Building is basmenet plus 2 stories with a roof deck
Any help is greatly appreciated
I am designing a rear addition in dc where the foundation will be built on the property line... We planned to build an L footer which we have done on several project in the past however the reviewer says the footer doesn't account for eccentricity... based on a 2500 Psf soil pressure we would need to offset the 8" cmu 4" from the party line with a 42" footer and build the addition with wood framing instead of cmu all the way up in order to keep the q max under the allowable soil pressure... my question is do you guys know any solutions that would allow me to buld to the property line with no offset either with cmu or wood framing
Building is basmenet plus 2 stories with a roof deck
Any help is greatly appreciated






RE: Eccentric wall footer
You could use perpendicular rectifying beams to take out the torsion and make the soil pressure more uniform.
RE: Eccentric wall footer
RE: Eccentric wall footer
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: Eccentric wall footer
KootK's link to a previous thread gives a lot of advice, some conflicting, and I don't think any of us would have changed our opinions.
RE: Eccentric wall footer
I usually align the bottom footing reinforcing with the vertical hooked bars if I use bottom reinf in the footing (not often) in addition to the hooked bars... I usually use hooked bars only and if I need the bond, provide a hook at the toe. Bond is not normally an issue for smaller sized bars.
Dik
RE: Eccentric wall footer
If the footing is 24" wide, it carries an allowable load of 2500 x 2 = 5000#/' at an eccentricity of 8". If the next floor is, say 96" above the footing, the required reaction at the upper floor is 5000x 8/96 = 417#/'. The moment varies from 3333'# at the footing to 0 at the next floor. The wall must be capable of resisting that moment without excessive rotation at the footing.
Soil pressure on the outside of the wall will help but should not be counted as it is on the neighbor's property and could be removed at his discretion.
BA
RE: Eccentric wall footer
RE: Eccentric wall footer
RE: Eccentric wall footer
BA
RE: Eccentric wall footer
Dik
RE: Eccentric wall footer
BA
RE: Eccentric wall footer
RE: Eccentric wall footer
RE: Eccentric wall footer
The footing can't put the wall in flexure unless the wall is laterally braced at some point above the footing. A horizontal reaction is needed above the footing to resist the eccentric moment.
BA
RE: Eccentric wall footer
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: Eccentric wall footer