Water Tank Wall (Tension Limit) 1

[Yousef ZAA]

Is there any tension stress limit on water tank wall (Liquid Containing concrete wall), the tension from 0-50 cm of bottom of wall is -3 MPa and then from 50 cm to it's full length(5.5 m) the tension is -1 MPa and the fracture stress is -3.5 MPa is this stress (-3 MPa at far end of the wall 0.5 m and then the stress is better)permitted in ACI, we are talking about a water tank wall it must have a tension limit

 

[briancpotter]

In ACI-350, I believe this is handled by a maximum allowable stress in the reinforcing (I think it's 20 or 24 ksi depending on what the reinforcing is used for). This, in turn, is a refinement of earlier provisions that specified a maximum allowable crack width (limiting steel stress accomplishes the same thing, more or less). This cashes out as requiring a lot of smaller bars spaced close together.

Brian C Potter, PE
Simple Supports - Back at it again with the engineering blog.

 

[JedClampett]

In the old days, ACI 350-89, the limits for the reinforcing in pure tension was 14,000 psi for 40 ksi steel and 20,000 psi for 60 ksi steel. These are working stress allowables. I don't think ACI 318 addresses pure tension cases. They like their concrete in compression.
What I would do is find a copy of the PCA "Design of Circular Concrete Tanks without Prestressing" It's an oldie but a goodie. This will give you an tried and true analytical method and suggest allowables. There's some subtle attributes in circular tanks that you might overlook without it. It sounds like you might either have it or are using an finite element model, which is fine, but I'd check your numbers vs. the PCA document.
Many small bars are better than a few larger bars. Be sure to stagger splices.