Deep Concrete Tank Wall Design for Shear
Deep Concrete Tank Wall Design for Shear
(OP)
I am working a 40'-deep underground rectangular concrete tank. Due to soil and Hydrostatic pressure loading, the wall thickness is becoming over 5 feet near the bottom. Any ideas to reduce the wall thickness..?
Can I use additional vertical reinforcement to help withstand the shear...?
Thank You.
Can I use additional vertical reinforcement to help withstand the shear...?
Thank You.






RE: Deep Concrete Tank Wall Design for Shear
RE: Deep Concrete Tank Wall Design for Shear
RE: Deep Concrete Tank Wall Design for Shear
RE: Deep Concrete Tank Wall Design for Shear
RE: Deep Concrete Tank Wall Design for Shear
RE: Deep Concrete Tank Wall Design for Shear
Adding shear reinforcement is a very good idea... it's not ideal for construction, but it keeps your cracks small, and will allow you to get a thinner wall... coupled with the fact that your shear will drop off rapidly the higher up the wall you go... I strongly suggesting adding some amount of reinforcement.
RE: Deep Concrete Tank Wall Design for Shear
For a 40'-0" deep tank, I'm not surprised that the walls are thick. By the way are you using two way action?
RE: Deep Concrete Tank Wall Design for Shear
RE: Deep Concrete Tank Wall Design for Shear
And thick walls and slabs may be needed.
RE: Deep Concrete Tank Wall Design for Shear
RE: Deep Concrete Tank Wall Design for Shear
RE: Deep Concrete Tank Wall Design for Shear
looking at Eq 11-4, you need to be closer to a 1,000 psi compressive load to even get your Vc to 3*sqrt(f'c)
RE: Deep Concrete Tank Wall Design for Shear
- The walls will be stepped up may be three times (Tapering may cost more)
- Internal Bracings are included the design
- We are looking at the shear at the bottom of the Wall not at a Distance d from it. I would like to leave this in the back pocket (last resort) if you will
- The structure is modeled in Risa -3d as a plate Element Model.
- Tieback system is not feasible for Easement issues.
Adding reinforcement at the bottom beyond what is required for flexural steel may change the mode of Failure of the section (i.e. we tend to design for Rho max to insure steel yielding first).
RE: Deep Concrete Tank Wall Design for Shear
Also, there are some hidden costs in stepping your walls; custom formwork, rebar bends, handling, shop drawing prep and review, etc. I once did a cost comparison for 50`x120'x24' tank, at the suggestion of the esteemed value engineer, and decided to stick with a constant wall thickness. As JedClampett pointed out, your comparing stepping costs to the cost of concrete material, not your unit wall cost.
I've modeled with RISA, but I've never had 5 foot thick plates. I'm curious, what size mesh does one use for a 5 foot thick element?
RE: Deep Concrete Tank Wall Design for Shear
As far as Risa, our model has 2'x2' mesh.
RE: Deep Concrete Tank Wall Design for Shear