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karimwassef
09/09/2017, 04:08 PM
The water volume is 2000 gallons. There will also be the weight of wood, glass, concrete, sand, and rocks. Plus the occasional 200lb human who might need to walk inside.

It's 12' x 8' peninsula.

The top of the base is also the bottom of the tank and made of a stack of 4 plywood layers 3/4" each = 3" thick plywood. This will be encased in epoxy.

The base is a matrix of 2x4s inside a 3/4" plywood skin. The skin also doubles as backup my on one side and a pressure lip against the glass bottoms.

Looking for feedback
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karimwassef
09/09/2017, 04:13 PM
I have a lot of support to distribute the weight on the concrete slab - otherwise, the slab cost skyrockets

karimwassef
09/11/2017, 11:38 AM
Little help? :)

I'm sure there's plenty of structural experts out there?

mcgyvr
09/11/2017, 11:51 AM
IMO...
Overkill on the front/back ends and under built in the middle..
From what I see the whole center of the tank is only supported by 4 2x's on end..
Looks like it could just fold in half..

But you are on your own here with that "monstrocity"..

I would be using more typical/proven subfloor/joist type framing if I was to do it..

All those horizontal 2xs are just held by screws in sheer too..
I don't like it personally..
Looks more like a "throw a crap ton of 2x's at it and hope I put enough" than a well thought out/Engineered support..

IMO of course..

karimwassef
09/11/2017, 01:35 PM
Your opinion counts, my friend.

It may look over-built in the ends but I was solving for the pressure distribution on the slab below. I'm not concerned with it holding up the tank. I needed to get below 700lb/ft2 (4psi)

http://www.reefcentral.com/forums/showthread.php?t=2644382&page=6

The middle is more open for accessibility. It's too deep to reach into so I have to physically fit under it.

The studs look sparse in the middle but the sides are 3/4" plywood skin. I considered adding plywood in other locations for cross-bracing.

karimwassef
09/11/2017, 01:43 PM
Looks like it could just fold in half..
The top is 3" of plywood sheets (4 x 3/4") glued and screwed. I think that the water weight in the center will be offset by the water weight on the ends?

But you are on your own here with that "monstrocity"..
Thanks. Don't call my baby a monster... she's just misunderstood.

I would be using more typical/proven subfloor/joist type framing if I was to do it..
So more frequent beams? Use a 2x10 for the joists? Details...

All those horizontal 2xs are just held by screws in sheer too..
for it to shear, the plywood skin would have to rupture in tension. I didn't consider dynamic loading but outside of an earthquake ...?

Looks more like a "throw a crap ton of 2x's at it and hope I put enough" than a well thought out/Engineered support..
Well- I don't usually hear "didn't think enough about it. Not engineered enough" but I'll take it :). Like I said, it was about managing psi on the slab.

ca1ore
09/11/2017, 03:12 PM
Good grief man, have you lost your mind ...... or maybe I'm just jealous :lol:

I am not a structural engineer - well, not an engineer of any kind - but I think if it were me I would think about incorporating LVL's in the mix. I built my current stand, and my new build stand, using laminated plywood beams and they've proven to be very effective. Compressive strength of 2x4 is very high, but the lateral strength and shear not so good.

mcgyvr
09/11/2017, 03:23 PM
Good grief man, have you lost your mind ......
.

You never seen a post from karimwassef before?

Out in left field is their happy place.. :lmao:

Someone has way too much time (and money) on their hands...

karimwassef
09/11/2017, 03:41 PM
Actually neither money nor time - just an over abundance of passion. If I had money and time, would it take me three years to design?

I love plywood- that's why the top and sides are plywood.

Studs are just best under compression or as beams. They're also cheaper when you're buying tons of wood (which this is)

My miniature model is made up of 1/2" plywood sections for the base to replicate the 2x4s. It was the closest scale model structure.

http://www.reefcentral.com/forums/showthread.php?t=2589632&page=25

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karimwassef
09/11/2017, 03:43 PM
By the way - I need help. If you're interested, I'm open to people coming in to assist build it

*** add legal stuff here that says do this at your own risk... no liability for me... only crazies need come.

karimwassef
09/11/2017, 03:45 PM
You see the concrete false floor? Even with the holes, it'll weigh 500-700lbs...

The glass panel weigh 400lbs each.

I only have 3 people so far (myself included) and one is my 70yo+ dad, God bless him!

karimwassef
09/11/2017, 03:48 PM
Back to the base... I'm adding more cross-beams and a couple of center plywood sheets.

karimwassef
09/11/2017, 11:51 PM
ok... update

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karimwassef
09/11/2017, 11:56 PM
This will actually make it easier to epoxy the whole thing.

The combination of studs and plywood should minimize shear.

The additional cross-members should minimize sag in the middle section.

Also, the green studs on the concrete will be bolted down into the slab.

More feedback??

jubei2006
09/12/2017, 06:21 AM
I think sheer may still be a problem as all the 2x are oriented in the same direction. You are counting on plywood screwed to 2x alone to keep the stand from folding up on you. If you were to have a wave maker the pressure of water pulsing on the side of the tank may overcome the holding power of screws and glue. I would feel better if part of the 2x were oriented east-west as opposed to all of them being north-south. But this is coming from a professional idiot fwiw

psidriven
09/12/2017, 06:46 AM
Not sure if its just in the illustration, but drilling holes that big in the horizontal beams to run your pipes might weaken them too much. Maybe run the pipes underneath the beams instead of through them.

karimwassef
09/12/2017, 08:17 AM
That's why I'm didn't run those 2x4 beams before. There isn't enough clearance from the top of the "sump lead in" tank to access the valves if I run the pipes lower. I would have to drop the sump another 3".

karimwassef
09/12/2017, 08:24 AM
I think sheer may still be a problem as all the 2x are oriented in the same direction. You are counting on plywood screwed to 2x alone to keep the stand from folding up on you. If you were to have a wave maker the pressure of water pulsing on the side of the tank may overcome the holding power of screws and glue. I would feel better if part of the 2x were oriented east-west as opposed to all of them being north-south. But this is coming from a professional idiot fwiw

That's what the plywood skin is for.

I need to access doors to be large enough for me to fit through.

I can look at adding more plywood panels in that direction

karimwassef
09/12/2017, 06:09 PM
how's this?

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there's plywood around each stud section as before

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jubei2006
09/12/2017, 06:42 PM
I like those footings much better, whether you have potential bowing north to south or east to west, you have substantial cross bracing to prevent that force from poping 2x like tooth picks. Guess now it would be making sure there are no point stresses on the tank bottom. Think i remember you saying the bottom was epoxied plywood? If done right that should help distribute the weight evenly, then major force to negate would be compressive downward force. Think there are formulas on line to see how much compressive force that tank would place and how much compression the 2x would handle

karimwassef
09/12/2017, 07:51 PM
The largest open span is ~ 2' x 3'

karimwassef
09/12/2017, 08:09 PM
also, 3" of plywood (4 layers at 3/4") glued together should make a very solid laminated structure. While plywood is not strongest in that direction, being 3" thick makes it about as thick as a stud. With another 3.5" for the 2x4s underneath means that there's 6.5" of wood holding it up.

If you consider that the water is only 27" max, that pressure is lower than most tanks that are sitting on particle board boxes with bigger spans than 24" x 36"...

karimwassef
09/12/2017, 08:22 PM
this is the limitation on studs...

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/1_zps0us3tqdw.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/1_zps0us3tqdw.jpg" border="0" alt=" photo 1_zps0us3tqdw.jpg"/></a>

I only have about 4.5" of clearance from the sump-run to the stud above... It was 8" before I added those 2x4s.

karimwassef
09/12/2017, 09:49 PM
I moved the plumbing wherever I could.. in the case of two of the returns, I ran them into the settling filter and out the sump-run...

The result is that none of the beams are compromised...

Wherever I could, I added more beams and studs without blocking access

I added a maneuverable dummy (not me :D) to see if I could fit.

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der_wille_zur_macht
09/12/2017, 10:01 PM
That strikes me as super crazy overbuilt, but I'm just a hack and it's better over than under.

If I lived near you, I'd be there in a heartbeat. I love being involved in other people's crazy ideas. Nearly as much fun as my own crazy ideas, but with less personal risk! :D

karimwassef
09/12/2017, 10:06 PM
Thanks. I did it to spread the weight to avoid making the slab impossibly expensive.

karimwassef
09/12/2017, 10:09 PM
you should visit my main thread... love getting more crazies' ideas together

here's the slab thread http://www.reefcentral.com/forums/showthread.php?t=2644382&page=6

and the main one http://www.reefcentral.com/forums/showthread.php?t=2589632&page=25

jubei2006
09/13/2017, 06:56 PM
In the words of undercover brother"SOLID". That stand will be as strong as a brick poo house. I would suspect it will outlast the tank, maybe the house itself which in my mind is a good thing if we're looking at supporting 8 tons of water.

Legot
09/13/2017, 10:12 PM
Just curious, why not use steel imbeded in the foundation? Wood just seems a little hackey at this scale, and it's a lot of work for no gain (or cost benefit) vs steel.

karimwassef
09/13/2017, 11:58 PM
cost. I can't afford a custom steel frame at this scale.
competency. I don't know how to DIY a steel frame.

I considered concrete block, but they add weight to the structure and I needed to reduce the pressure on the slab.

wood I can afford, is lightweight and I can DIY.

karimwassef
09/14/2017, 07:56 AM
I added a walk through video of the build on my main thread

http://www.reefcentral.com/forums/showthread.php?t=2589632&page=25

If you're structural-design and DIY biases, please take a look at how the support comes together.

jphayes921
09/15/2017, 02:36 PM
Why not pour a concrete form and apply plywood on the outside for the looks? You can still run the pipe in the concrete and might be less of a head ache in the end. IMO

karimwassef
09/15/2017, 04:04 PM
It would be too heavy. My first solution was concrete block with rebar tied to the slab and filled with concrete... cheap and relatively easy.

Unfortunately, the cost of the slab exploded to $20k to support the weight of the tank, concrete, etc...

I also got the finger waving of experts who advised me that I'm going to kill myself using concrete... that the slab will crack and I'm going to fail miserably (and die)...

So- in the interest of controlling weight, and cost, and sanity, and life :D... I went with what I know.

bblumberg
09/17/2017, 08:26 PM
How about the precast concrete double T-sections that they use for parking lot floors and such?

Like these http://www.oldcastleprecastspokane.com/core/files/oldcastleprecastspokane/uploads/images/Pics/DSC_0001.JPG

I have no clue what these cost, but they are almost certainly strong enough and might be workable for your application...

karimwassef
09/17/2017, 08:40 PM
That's commercial construction :D

That's a whole other cost level

kalare
09/18/2017, 11:21 AM
I'm a structural engineer. I don't think you need 3 layers of plywood at bottom, but if you have it cheap, I suppose why not? How high is the water? I wouldn't span the plywood more than 2 feet without a 2x4 support joist, and I wouldn't span the 2x4 support joists more than 4-5 feet without a load bearing wall/post at each end. This will result in a super overbuild stand, but it would be my preference to limit deflection of the plywood bottom.

I'm curious, you have what is effectively a solid 2x4 wood bottom at one end where the spans are shorter, and at the other end, you have no joists? I really recommend adding at least 2x4 at 16" on center at the other end, especially since it has the longest span. Having a super strong base on one side of the tank and very light framing on the other side makes no sense, what works on one side should work everywhere, and I would note that I do not trust it to work. I would also recommend having the center load bearing support at the other end as well...if that's not possible due to sump or other issue, provide a network of 4x beams (deeper than 3.5" section).

The user that mentioned the pipe penetrations through the 2x4 members is absolutely correct. The amount of load those members can support will be tremendously reduced. shear capacity of those members at the penetration will be reduced by what looks like 80% or so, bending capacity, most like 50%.

For a tank this size, I would personally use 2x6 (or possible 2x4 @ 12" on center, with more support lines), and drop the plumbing below the framing, with absolutely no penetrations through the joists. Can you not add a support line on either side of the central plumbing line? The way it's currently framed you have a central double 2x4 spanning from center support out front, to the single 2x4 in the rear that is penetrated. You really need to add more support in this area somewhere.

Another note, your support lines are 2x4 and they will be clad with plywood? You should construct your supports similar to a typical wall, they will be much stronger that way and you'll use less wood. The way you have your 2x4 oriented makes them weak. The plywood should be attached to the small dimension of the 2x4, not the large dimension. As shown, the support walls can buckle out of plane much more easily. (Note, I've just seen some renderings further down the first page that appear to correct this issue)

Sorry if I've been blunt or offensive, just want you to be safe! I'm sure some of the above was not clear, let me know if you need more clarification. Good luck!

karimwassef
09/18/2017, 11:33 AM
AWESOME! Thanks. Actually, I think I've corrected a lot of what you said -

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I also have a link of a walk through video for the whole build that I'll link

<iframe width="560" height="315" src="https://www.youtube.com/embed/z00RZimQGks" frameborder="0" allowfullscreen></iframe>

karimwassef
09/18/2017, 11:43 AM
The cavity has to be large enough for me to enter and work as well as support the sump and plumbing.

I've put 2x4s on 12" wherever I could

karimwassef
09/18/2017, 11:44 AM
The largest plywood window span is where the plumbing connects at 2'7" x 3'

karimwassef
09/18/2017, 12:05 PM
I'll take some pictures with dimensions to help.

The plywood isn't cheap, but with a 12'x8' tank, I can get a single sheet to cover the span.

So I use 3 full sheets and overlay glue to create a solid sheet. I had a thought to pre-stress the sheets by slightly bowing them upwards as I glue them but I decided to avoid that complexity and risk.

So 3 sheets then an overlapping 3 sheets cut to cover the seams, then 3 sheets over that covering those seams, then 3 sheets over those cover those seams. So 12 sheets in total at 3" thick with all seams double covered. That's $480 in plywood for the base!

Not cheap, but I think it should hold a lot of weight, especially with 2x4s under it again.

karimwassef
09/18/2017, 12:17 PM
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karimwassef
09/18/2017, 12:23 PM
the side doors are big at 4' 10" but it's a cramped area that I need to crawl into. The whole structure sits "underground" since the surrounding floor is actually raised up (clearer to see in the video).

I've also created access "tunnels" through the long end, but there's a lot of plumbing. I'm not a little guy, so I'm sensitive to creating enough maneuvering room to turn a wrench!

A couple of those fittings are large. The overflow is 4" diameter and the emergency drain is 3". The other pipes are 2". Those all take substantial effort, in my experience, to work with. So - need some elbow room :D