Stepped Footing
Stepped Footing
(OP)
Is there some standard way to handle the transition area in a stepped footing/foundation?
See the attached pdf. Footing shown could be round or square, reinforced concrete.
Summing moments about a centerline as in Section A allows you to solve for steel tension and area, concrete compression, etc., and all is well.
Summing moments at Section C does the same for the reduced section beyond the step.
The problem is at Section B. The cross section is similar to Section A, but obviously, near the edge, you can't support the concrete compression at the upper surface.
A similar issue would arise if the transition were sloped.
Various handbooks and textbooks in the office mention stepped or sloped footings, show diagrams of them, but neglect to mention how the step itself would normally be addressed in the design. Google turns up similar references that also omit details of how to handle the step.
Any input or references would be appreciated.
See the attached pdf. Footing shown could be round or square, reinforced concrete.
Summing moments about a centerline as in Section A allows you to solve for steel tension and area, concrete compression, etc., and all is well.
Summing moments at Section C does the same for the reduced section beyond the step.
The problem is at Section B. The cross section is similar to Section A, but obviously, near the edge, you can't support the concrete compression at the upper surface.
A similar issue would arise if the transition were sloped.
Various handbooks and textbooks in the office mention stepped or sloped footings, show diagrams of them, but neglect to mention how the step itself would normally be addressed in the design. Google turns up similar references that also omit details of how to handle the step.
Any input or references would be appreciated.






RE: Stepped Footing
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: Stepped Footing
Another approach would be to consider the corner of the footing as sloped at a 1:4 slope. That's how RAM concept does it for drop panels.
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: Stepped Footing
Here is a quote and diagram from a 1921 ASTM paper:
The whole idea of having a stepped footing is a carryover from pre-concrete days when masonry footings were the norm. The masonry steps were sized based on conservative rules-of-thumb that in turn came from experience. When reinforced concrete came into use, soil mechanics was advanced enough to allow informed decisions to be made, instead of following tradition.
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RE: Stepped Footing
RE: Stepped Footing