basic foundation overturning question
basic foundation overturning question
(OP)
been using too much software. i forgot the basic lol.
if i dont have horizontal force and only unbalanced vertical force, is there overturning moment for stability?
i'm confused because if i do summation of moment at the edge of footing, all forces are righting moment and no overturning.
but there is overturning due to unbalanced vertical force at the center.
if i dont have horizontal force and only unbalanced vertical force, is there overturning moment for stability?
i'm confused because if i do summation of moment at the edge of footing, all forces are righting moment and no overturning.
but there is overturning due to unbalanced vertical force at the center.






RE: basic foundation overturning question
RE: basic foundation overturning question
Then go form there.
RE: basic foundation overturning question
RE: basic foundation overturning question
BA
RE: basic foundation overturning question
Thank you.
Regards
Engr. Faisal
RE: basic foundation overturning question
The center of resistance, will be exactly under the resultant load and will be higher at one end than the other.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: basic foundation overturning question
RE: basic foundation overturning question
That would include moments due to lateral forces, but also, any moments causing anything but uniform soil pressures on the foundation pad.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: basic foundation overturning question
For simplicity let us ignore the weight of the footing.
R = 10 Kips. eccentricity w.r.t. c.g. of footing = 2'-6".
Overturning moment about the base = 25 kip.ft.
Restoring moment about the toe = 10 * 5 = 50 kip.ft.
F.O.S. against overturning = R.M. / O.M. = 50 / 25 = 2
Eccentricity lies outside the kern of the section. 75% of the footing is effective. The c.g. of soil pressure coincides with the 10 kips load.
RE: basic foundation overturning question
can you suggest me any book reference or link of your calculation please?
Thank you.
RE: basic foundation overturning question
I believe this is what DST148 has done in his calculation.
RE: basic foundation overturning question
thats the confusion. some engineers dont consider unbalanced vertical force to be included in FS against OT.
RE: basic foundation overturning question
On few occasions (in low seismic zones) we had truly isolated footing not connected to the main structure. In such rare cases we designed the footing for axial load + moment due to horizontal load of about 2.5% of axial load applied at the top of the pier, even though the axial load on the pier was concentric.
RE: basic foundation overturning question
This is a bearing pressure issue: P/A + M/S.
RE: basic foundation overturning question
not saying staad foundation is the authority for this though. but staad is a respectable software.