combined footing with 2 columns not on the same line

[malikasal]

can anyone provide a an example/theory/equation , for calculating the reinforcement of a combined footing with 2 columns not on the same line ???

Any information will be useful



ôIf you don't build your dream someone will hire you to help build theirs.ö

Tony A. Gaskins Jr.

 

[hokie66]

Why can you not build the footing so that the columns are both central to the footing axis? If this is a special case with required dimensions, perhaps you should provide a sketch.

 

[malikasal]

Here is a quick sketch to illustrate the case (sorry about the bad sketching , i did it with my phone) .

ôIf you don't build your dream someone will hire you to help build theirs.ö

Tony A. Gaskins Jr.

 

[TehMightyEngineer]

What hokie said, skew the footing so both columns are on the centerline. Design like a normal combined footing except now you have diamond shaped columns instead of squares.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[malikasal]

WE tried that guys, but it didn't work because we have some geometrical restrictions.



ôIf you don't build your dream someone will hire you to help build theirs.ö

Tony A. Gaskins Jr.

 

[mike20793]

I'd model it in SAFE, but I'm guessing that may not be an option here. What kind of loads are you dealing with? Are these columns from frames or just gravity columns?

 

[malikasal]

Unfortunatly safe is not an option,i have to use hand calculations, the loads are only axial loads (gravity columns )

Any ideas ??



ôIf you don't build your dream someone will hire you to help build theirs.ö

Tony A. Gaskins Jr.

 

[KootK]

It is an option to skew the footing. Think parallelogram rather than rectangle. That said, 500 mm is nothing so long as your footing width will be substantially greater than that. You can probably just ignore the offset. Alternately, you could account for the offset locally at each column by designing the short direction at each end as eccentric footings.

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.

 

[jayrod12]

Those geometrical restrictions should be included on your sketch so we understand the entire problem.

 

[BSVBD]

I use ENERCALC.

If i'm not satisfied with the Combined Footing result, i will size (2) separate footings and make all necessary design alterations to combine the (2)... i.e. worse case rebar supersedes, total required area, etc...

As others have stated, this depends on specific parameters and restrictions... need more info...

 

[jike]

You have not indicated what your geometrical restrictions are. Not sure if this would work but you may try 2 separate footings and strap to counter act any eccentricities.

 

[TehMightyEngineer]

Yep, strap footings should work in the same footprint as your sketched footing.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com