karimwassef
Active member
The largest open span is ~ 2' x 3'
Wood base - heavy load 17000 lbs
- Thread starter karimwassef
- Start date
karimwassef
Active member
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"...
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
Active member
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.
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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
Active member
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
) to see if I could fit.
<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/3_zpstmdzqqvu.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/3_zpstmdzqqvu.jpg" border="0" alt=" photo 3_zpstmdzqqvu.jpg"/></a>
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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
) to see if I could fit.<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/3_zpstmdzqqvu.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/3_zpstmdzqqvu.jpg" border="0" alt=" photo 3_zpstmdzqqvu.jpg"/></a>
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der_wille_zur_macht
Team RC
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!
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!
karimwassef
Active member
Thanks. I did it to spread the weight to avoid making the slab impossibly expensive.
karimwassef
Active member
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
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
karimwassef
Active member
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.
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
Active member
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.
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
New member
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
Active member
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... I went with what I know.
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
... I went with what I know.How about the precast concrete double T-sections that they use for parking lot floors and such?
Like these http://www.oldcastleprecastspokane....ecastspokane/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...
Like these http://www.oldcastleprecastspokane....ecastspokane/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
Active member
That's commercial construction
That's a whole other cost level
That's a whole other cost level
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!
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
Active member
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>
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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>
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karimwassef
Active member
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
I've put 2x4s on 12" wherever I could
karimwassef
Active member
The largest plywood window span is where the plumbing connects at 2'7" x 3'
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karimwassef
Active member
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.
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.
