Design Calculations for Circular Concrete Tanks w/o Prestressing
(Version 1.0 - 6/1/99, Based on Dwg. IA 900 - 5/99)
Project: Circular Tank Checked by:
Designer: NRCS Employee
Date: 2/4/2017 Date:
Input Design Data
Inside tank diameter (feet) ? 90.0 (Maximum 120-foot diameter)
Tank wall height (feet) ? 12.0 (Maximum 14-feet tall)
Watertight wall to ring foundation joint (method)?
Additional 1/4" x 6" steel plate required (feet) ? 0.0 (Other than at the wall to ring foundation joint)
Select radial steel (Asr) bar size ? (Asv spacing greater than 9'' use #4 bars at 1/2 As
r length for radial steel in footing and wall (feet) ? (Optional, generally bar lengths are 20 feet)
Place floor slab monolithically with wall footing ? (If no, footing assumed to be isolated from floor sla
stance from footing edge to tile centerline (feet) ? 0.5 (4" tile diameter)
Length of tile outlet (feet) ? 200.0 (4" tile diameter)
Distance from wall centerline to fence (feet) ? 5.0
Input other concrete used in project (sq.ft) ? 320.0 (unloading slabs, etc.)
Thickness of other concrete (inches) ? 6.0
Extra concrete delivered to site (percent) ? 0.0 (Safety factor, applied to each concrete quantity)
Extra steel delivered to site (percent) ? 0.0 (Safety factor, applied to steel total length)
Select desired floor slab joint spacing (feet) ? 90 (A joint is assumed between footing and floor slab)
Select grade of floor steel (ksi) ? (Note: this only applies to the floor steel,
Excavation quantity (cu.yd.) ? 0.0 wall and footing steel shall be Grade 60)
Subgrade fill quantity (cu.yd.) ? 0.0
Backfill quantity (cu.yd.) ? 0.0
Drain fill quantity (cu.yd.) ? 0.0
Number of concrete chairs ? 0.0
Other: Other Quantity 0.0 Lin. Ft.
Tank Design Information
Floor Slab Thickness (inches) = 5
Wall Thickness (inches) = 10
Footing Width (inches) = 48 (Required soil bearing pressure = 2000 psf)
Footing Thickness (inches) = 12
Footing Overhang (inches) = 14
Concrete Compressive Strength (f 'c, psi) = 4000 (Required strength for all concrete)
Footing Radial Steel (As1) = #4 @ 8.0" (Place radial steel on top of ring steel)
Footing Ring Steel (As2) = #4 @ 6" (Place ring steel 3 inches above footing base)
Wall Vertical Steel (Asv) = #4 @ 8" (Place vertical steel on the outside of the ring steel
Wall Ring Steel (Asr) = #4 @ 6" (Ring steel must be placed in the center of the wall
Tie Bar Steel = #4 @ 8" (Secure all tie bars to footing radial steel)
Floor Slab Steel (Floor Steel) = #4 @ 12"
Floor Steel Splice Length (inches) = 20
Wall Ring Steel Splice Length (inches) = 20
Footing Ring Steel Splice Length (inches) = 20
Tank Capacity (ft3) = 63617 (Assuming 1-ft. freeboard, 6-in. sediment, 6-in. rainf
Written by: NRCS Design Staff
Federal Building
210 Walnut St., Ste. 693
Des Moines, IA 50309-2180
63617
56562
4
ing foundation joint) 1
9'' use #4 bars at 1/2 Asv)
ngths are 20 feet) 1
be isolated from floor slab) 1
ach concrete quantity)
teel total length)
en footing and floor slab)
the floor steel, 1
teel shall be Grade 60)
ssure = 2000 psf)
f ring steel)
bove footing base)
outside of the ring steel
in the center of the wall
ng radial steel)
6-in. sediment, 6-in. rainf
Additional area that requires sandblasting (sq.ft.) ?
Additional area that will be air-water cut (sq.ft.) ?
Additional hydrophilic waterstop required (feet) ?
Additional 1/4" x 6" steel plate required (feet) ?
