Residential Concrete Column
Residential Concrete Column
(OP)
I am currently working with an Architect on his new residence. He is using 16" dia sonotube formed concrete columns to support a porch. They are only carrying 5.5K of load and are 6'-8" above grade. The size is purely for aesthetics. Do I need to follow ACI requirements for reinforcing of these columns or is there an exemption for such lightly loaded elements? ACI requires (5)-#6 with #4 ties at 3" o.c. max. Seems a bit much.
Thanks.
Thanks.






RE: Residential Concrete Column
The area of the 5 No.6 verts/Ag is about 0.01 so I don't know if you can drop it any further. ACI 318 Sec 10.9.1
Out of interest, what ACI sections did you use to come up with size and spacing of lateral reinforcement/ties?
RE: Residential Concrete Column
I would go with the 1% minimum myself, but that's me. It seems like #3 ties at 12" should be ok. You do have the option of arranging the reinforcing in a rectangular cage if you want. That's usually cheaper than cicular ties and vertical bars in a circular pattern.
RE: Residential Concrete Column
RE: Residential Concrete Column
RE: Residential Concrete Column
RE: Residential Concrete Column
RE: Residential Concrete Column
Axial stress is less than 30 psi on the gross area. the height is only 6'-8" (if I understand correctly) What is all the reinforcing going to do other than insure that is won't break up when it falls over? Even a single bar might provide that.
Connections at the top and bottom of the column would seem to be far more critical than a 4 bar cage in the thing. Maybe 4 dowels out of the foundation would provide some fixity at the base to promote safety but above that I'd expect very little bending stress and likely well within the capacity of plain concrete. Also, the code allows reinforcement 33% greater than that needed by analysis.
I haven't look at ACI for plain concrete in a while but I would expect that there are some provisions there for such a case.
RE: Residential Concrete Column
RE: Residential Concrete Column