Concrete wall thickness 1

[BoomerSooner7]

Hello,
I am building a water containment wall surrounding process water tanks. The wall is boxed in to form a rectangle, dimensions are approximately 500" W x 300" L x 55" H. So the maximum pressure the wall would see is 55" of standing water. The wall will have rebar going into existing concrete floor. My question is how thick does the wall need to be assuming 3000 psi concrete.

thanks.

 

[a2mfk]

This has nothing to do with me being an FSU alumnus- everyone on this board will tell you to hire a licensed structural engineer for this project. And if you are one, then they will beat you up worse than your football team did mine this year

 

[hokie66]

12"

 

[Brad805]

Come on Hokie, he's Industrial. Industrial guys build big or go home.

Brad

 

[hokie66]

I know. I thought 12" was big enough.

 

[delagina]

looking at aci 350, am i right that minimum thickness of wall is 4" for less than 10 ft?

 

[BoomerSooner7]

Boy I hope you're right delagina. Right now we're thinking 8" but that's based on the "good ol' boy" philosophy of bigger is better or someone could say the "industrial engineer" philosophy

That was a great game, huh a2mfk?

 

[hokie66]

Your structural engineer could make an 8" wall work. Don't even think about something thinner.

 

[BoomerSooner7]

From the limited resources I've found online on ACI 350R (thanks delagina), it lists 8" for a minimum thickness for walls under 10'. It also lists a maximum spacing of 12" for rebar, sorry for the dumb question, but would this be referring to the vertical supports only or both vertical and horizontal?

 

[msquared48]

2" post-tensioned.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[apsix]

Minimum thickness and maximum spacing is just what it says, it doesn't tell you what you need.

The existing floor will also have to be checked if the walls are cantilevering from it.

 

[HSIII]

Mike,

Really? 2" post-tensioned? How thick are the strands, and what's the spacing?

Go with 12" thick, just because 12 is a good solid number, lol.

In all seriousness, if the reinforcing is doweled from the slab into the wall, you do have to incorporate the slab as some form of heel. Have you thought about adding a toe, maybe as a possibility to reduce your wall thickness? Also, depth of cover (frost cover)?

Like I said in the other forum you posted this in, it would be extremely wise to invest in a PE to do this design work for you. Experience is always a good thing, and may save you boatloads of money in case a catastrophic event happens and the wall somehow fails under the hydrostatic pressure exerted on it, including initial water impact.

 

[HSIII]

BTW Mike,

Upon reading my comment, I was not trying to come off as a jackass, I am really curious if a 2" post-tensioned wall would really work under a certain reinforcing circumstance.

 

[hokie66]

HSIII,
Mike was joking. A 2" wall won't work, stressed or not.

BS7,
I didn't catch the part about this wall cantilevering from an existing slab. Don't know how you would do that, as the slab would have to be thick enough and well enough reinforced to serve as a footing, and the vertical reinforcement would have to be developed into the slab, not just stuck in a bit and glued. So again, get a structural engineer involved in your design.

 

[csd72]

Actually, to get waterproof concrete with two layers of reinforcement and the appropriate cover I would say 12" is the minimum that you could get this to work.

This is what we use for basements over here.

 

[hokie66]

csd72,
I agree, if it is a water containing structure, in which case I would also use better concrete than 3000 psi. But on rereading the thread, I took this to be just a temporary containment in case the process tanks failed.

 

[BoomerSooner7]

Yes hokie you are correct, this is a secondary containment wall in the event of a tank failure. We normally use 3500-4000 psi concrete.

 

[a2mfk]

craigslist ad: "Need experienced structural engineer (PE) for design of a water retaining concrete structure."

Everyone needs work these days, stop hogging it all.

My first post, IMHO, was perfect and the rest of you guys had to ruin it.

Is that an industrial thing to use all inches? What's 500" x 300"? I'm not very good at math...

 

[a2mfk]

2" post-tensioned

"That ain't going nowhere"
- anonymous contractor at every jobsite I've ever been to...

 

[hokie66]

a2mfk,
Sounds like he is trying to promote a simpler, more logical system of dimensioning. The next step is to use all millimetres, like the rest of the world.