multi cell circular concrete structure
multi cell circular concrete structure
(OP)
We are considering taking on a project that involves the design of a multi-cell circular concrete structure, specifically a combined digester and settling basin. The chambers are separated by concrete slab, which has a hole in the middle through which a shaft passes that drives scrapers. The diameter is about 40 feet, the overall height is about 30 feet, with the slab located about 10 feet down from the top. I have checked the PCA document for the design of circular concrete tanks, but the slab with the hole seems to put this structure beyond the scope of the PCA book.
My question: Is anyone aware of a design guide for a structure as described above? I have contaced PCA and have not heard back from them yet. ACI 350 doesn't give any design aids for the design of environmental structures.
My question: Is anyone aware of a design guide for a structure as described above? I have contaced PCA and have not heard back from them yet. ACI 350 doesn't give any design aids for the design of environmental structures.






RE: multi cell circular concrete structure
have done similar but with rectangular configuration, or single circular only.
best, tincan
RE: multi cell circular concrete structure
RE: multi cell circular concrete structure
I assume you mean that the lower chamber could be empty while the upper chamber was full, which of course puts substantial loads on the slab (and on the footing under the shell). If operating conditions were such that both chambers would always be filled, the only load would be the dead weight of the slab, which shouldn't be hard to support.
In the steel tank business, we periodically get inquiries from people that want to divide tanks, either with a diaphram across as you indicate, or with an inner and outer tank, or with a vertical divider. In all cases, it estimates out cheaper to build two separate tanks. In the case of concrete, I think the inner-outer annular tanks would work okay, but otherwise, I'd suggest comparing cost to two separate tanks as an option. Unless, as mentioned, the chambers are maintained full at all times.
RE: multi cell circular concrete structure
Tincan
RE: multi cell circular concrete structure
Check PCA (Portland Cement Assn.) for a bulletin on "Circular Concrete Tanks" they give the radial and tangential moment coefficients for moments in a circular slab without center support. Don't have the exact title, mine has been misplaced/borrowed. However, the coefficients are:
POINT
0.0R 0.1R 0.2R 0.3R 0.4R 0.5R 0.6R 0.7R 0.8R 0.9R 1.0R
Radial Moment Mr
.075 .073 .067 .077 .043 .025 .003 -.023 -.053 -.087 -.125
Tangential Moment Mt
.075 .074 .071 .066 .059 .050 .039 .026 .011 -.006 -.025
Moment = Coeff x pR^2 (p = uniform loading)
+sign denotes compression in surface loaded.
0.0R denotes center of slab,
best, Tincan
RE: multi cell circular concrete structure
RE: multi cell circular concrete structure