Reinforced concrete deep walls help
Reinforced concrete deep walls help
(OP)
I have been trying to find some information out about a deep reinforced concrete rectangular vault I am designing. The dimensions are 26' x 30' x 29' deep. Using "Rectangular Concrete Tanks" I am getting a wall thickness between 22" and 28" based on shear. Does this seem reasonable? It sounds a little big but I don't know how I would determine it otherwise. I am using a lateral force of 135 pcf x 0.6 (at-rest coefficient) based on geotechnical.
Any help with this would be appreciated.
Any help with this would be appreciated.






RE: Reinforced concrete deep walls help
RE: Reinforced concrete deep walls help
RE: Reinforced concrete deep walls help
RE: Reinforced concrete deep walls help
RE: Reinforced concrete deep walls help
I participated in the forensic evaluation of an above ground sewage treatment plant - aeration basin walls had failed. The tank had been designed using ultimate strength design techniques (a precursor to LRFD) instead of ASD. The as-built walls were 14 inches, while ASD would have dictated 20+ inches. Oh, and the basin walls were only about 15 feet high, and the fluid unit weight γsewage = 63 pcf. That's considerably less than the γ = 81 pcf you have assumed, and your wall is twice as high. Your design γ = ( (135-63)*0.6 + 63 ) = 106 pcf if the GWT is at the ground surface.
Proceed with caution...
Perform an ASD design to check your current calculations. If there's a big difference, you have a problem...
Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.
RE: Reinforced concrete deep walls help
Could you clarify what ASD Design is and where I can find it?
RE: Reinforced concrete deep walls help
How are you performing the design - by "hand", or computerized design package?
Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.
RE: Reinforced concrete deep walls help
I am performing the computations by hand using PCA's resource "Rectangular Concrete Tanks" to analyze the structure, which gives factors based on finite element analysis for these types of structures.
RE: Reinforced concrete deep walls help
The working stress would put you at approximately 22,500#/ft of shear at the mid-span (worst point). Without the factored loads, and f'c = 3500psi & 65psi shear,
22500/12(65) = 28.8 inch d. 28.8 + 1/2 bar thickness + 2" cover==> 31+. Your numbers are not out of whack, I did a 75' x 100' x 25' deep recently, had the same order of magnitude. Focht3 has good advice, Best of luck
Tincan.
RE: Reinforced concrete deep walls help
RE: Reinforced concrete deep walls help
RE: Reinforced concrete deep walls help