Thermal Stresses in Circular Concrete Tanks 1

[dmessayons]

I am designing a conventionally reinforced, above-grade circular concrete tank. I am concerned with potential thermal stresses in the walls. Any suggestions or references would be appreciated.

Thanks.

 

[JedClampett]

Before you worry about thermal stresses, you need to perform the initial design. Luckily, the basic design and thermal stress effects are in the same book, "Circular Concrete Tanks without Prestressing" by Portland Cement Association (PCA). You need to get it.

 

[dmessayons]

Thanks Jed.

It looks like the PCA concentrates on hoop stresses and circumferential moments. I'm looking for discussion of the vertical moments/stresses induced in the walls due to temperature gradients. Any thoughts?

 

[JedClampett]

I think that due to the inherent flexibility in the vertical direction, these forces are not a problem.

 

[corus]

It depends on which direction the thermal gradient applies. If it's a radial gradient then you need to consider plane strain effects. If it's an axial gradient then the solution depends on the restraints near the gradient. For normal structures I'd refer to any book on thermal stresses. For reinforced concrete, I don't know.

corus

 

[PEStructural]

Additional hoop steel in walls, As = ( 9 t^2 T ) / ( 17,500 d ); where As = Additional hoop reinforcing in square inches, t = Wall thickness in inches, T = Temperature differential in degrees Ferenheit, d = Distance to tensile reinforcing in inches (approx t - 2.5").

This reinforcing is added to the area of reinforcing that you calculate for the "normal" hoop tension.

Hope this helps.