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Concrete wall thickness

Concrete wall thickness

Concrete wall thickness

(OP)
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.  

 
 

RE: Concrete wall thickness

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 :)

RE: Concrete wall thickness

12"

RE: Concrete wall thickness

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

Brad

 

RE: Concrete wall thickness

I know.  I thought 12" was big enough.

RE: Concrete wall thickness

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

RE: Concrete wall thickness

(OP)
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?

RE: Concrete wall thickness

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

RE: Concrete wall thickness

(OP)
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?

RE: Concrete wall thickness

2" post-tensioned.

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

RE: Concrete wall thickness

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.

RE: Concrete wall thickness

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.

RE: Concrete wall thickness

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.

RE: Concrete wall thickness

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.

RE: Concrete wall thickness

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.

RE: Concrete wall thickness

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.

RE: Concrete wall thickness

(OP)
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.   

RE: Concrete wall thickness

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...

RE: Concrete wall thickness

2" post-tensioned

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

RE: Concrete wall thickness

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.

RE: Concrete wall thickness

Contractors....

Nevermind, I won't vent here, that'd just be wrong and petty.

RE: Concrete wall thickness

The word is contradictors, not contractors.

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

RE: Concrete wall thickness

BoomerSooner7,

All the design advice above is intended for preliminary design only and should not be taken as a substitute for professional structural engineering advise.

a2mfk,

You happy!

RE: Concrete wall thickness

csd- YES!!! Merry Christmas to all!

Hokie- I know where you are coming from. Been to Spain a few times and hung out on some job sites lending a hand. The tape was in CM and so were the plans, so your room dimensions would be like 440cm x 300cm, and besides the Spanish it was an easy system to get the hang of.

Sometimes when doing tile and woodworking work around the house I use a metric tape because the dimensions are easier to work with and remember.

I digress. Have a good holidays everyone.

RE: Concrete wall thickness

a2mfk,
The Spanish have still got it wrong if that is the case.  The dimensions should be in mm, not cm.  Dressmakers use cm, engineers use mm.

RE: Concrete wall thickness

hokie, my turkey loving friend, that is what decimal places are for....  And we ain't building rockets or car parts :)

If its good enough for Calatrava, its good enough for me!

RE: Concrete wall thickness

Well, not for me.  If it's not in multiples of 10^3, I don't use it.  The French persist in using kg/cm^2, but the Spanish should know better.

RE: Concrete wall thickness

But how does that work when the marking crayon is at least 5mm wide?

Have a good christmas everyone.

RE: Concrete wall thickness

(OP)
My bad, I guess I posted this in the smarta*s forum by mistake :). I am fully aware there is no substiture for paying a PE to give professional advice, however I thought I would try to get some preliminary advice from people who might have some experience with a similar structure.  Anyway, thanks to everyone who had something worth saying.

Merry Christmas and Happy New Year to everyone!

RE: Concrete wall thickness

Boomer- Our responses were as such because this forum is not a free structural design service website. To do so would violate the code of ethics of our licenses, and if I were you, I would not blindly accept the advice of strangers on a message board. Any one of us could have called out something that would have probably worked for your situation. Its the probably that you need to be careful with.

The forum as I understand it is geared for working structural engineers (not even students) with specific questions on a problem they have, more of a push to get over the hump, than "how do I design this?"...

Its certainly not personal, and yes, there are some ball busters - even if you are a structural PE you better provide a sketch and give us all the info!!

 

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