huangyhg

foundation with two way eccentricity
i have a column with uplift and horizontal reactions in two directions at the base. i would like to size the footing to resist the uplift and keep the dimensions as small as possible. i have a copy of principles of foundation engineering by braja m. das that i am using to calculate the effective bearing area and soil bearing pressures. my question is, besides the bearing capacity of the soil, what else should i be concerned with in sizing the footing? at what point does this become unstable? do you think that the footing is acceptable as long as i maintain an adequate factor of safety against overturning on the individual footing? say (otm)/((ftg wt) x ftg length/2)) > 1.5
also maintain an adequate factor of safety against sliding.
daveatkins
keep your resultant within the kern distance.
not necessary to keep within the kern - as long as the bearing pressure under the reduced bearing area is acceptable.
i usually look at eccentrically loaded footings similar to a retaining wall foundation which that book you have cover very well. you have max bearing pressure at the "front" to check(two dirs in this case). uplift on the "back". overturning. i doubt sliding will be an issue if you dont have lateral force. besides that, the footing itself needs to be designed. for this, you probably should look at a concrete book.

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