Effective area of a circular foundation

[mahisub]

As you know, load eccentricity decreases the ultimate vertical load that a footing can withstand. This effect is accounted for in bearing capacity analysis by reducing the effective area of the footing.
Does anyone know a solution for effective area in circular bases?

There is something in API PR2A-WSD, section C6.13, whch seems to be wrong!!

 

[jdonville]

mahisub,

Suggest that you make simplified and/or conservative assumptions to extend the theory with respect to rectangular/square footings to a circular area.

Jeff

 

[oneintheeye]

why not design using actual dimensions. Apply moment and work out + and - pressures due to moment. Then dimension to eliminate negative values. i.e. tension on any side.

 

[fattdad]

With the eccentricity the effective shape goes from a circle to a football. Just a matter of geometry.

f-d

¡papá gordo ain’t no madre flaca!

 

[JoeTank]

(Mark?) Fintel's Concrete Structures Handbook treats this problem exactly. No guessing required.

Joe Tank

 

[BigH]

JoeTank: Good for you - yes, it is Mark. Section 5.2 for what he is looking at. Sadly, my book had a printing error for Figure 5-5 "Bearing Pressure distribution under eceentric loading" - (Light print).