Monster tank stand design

[ghbrewer]

Have you priced out a steel stand? I mean no disrespect, but a steel stand would just make more sense for a tank of this size, IMHO. I know they can be a little pricey, but you really have to weigh that against the damage and losses that would occur if the tanks seems were to fail or if a crack developed.

I highly suggest you read the following thread (if you have not already) b4 you make your mind up: http://www.reefcentral.com/forums/showthread.php?t=2096730&page=34">http://www.reefcentral.com/forums/showthread.php?t=2096730&page=34</a>

Starting with post #838, then on for a few pages. While this was not directly linked to the stand (at least I don't recall that being the case), it still reinforces the type of catastrophe that can occur and what I hope no other hobbiest has to endure. What a loss....

 

[grouper therapy]

ghbrewer;1050381 wrote: Agreed, I just didn't want to come out and say that he can't use dimensional lumber. It can be used as well, if designed for and built properly. Using an appropriate plywood laminated using screws and glue would make for a much stronger and more mechanically sound structure, but still inferior to a steel stand. A steel stand would alleviate a lot of concerns in this case, especially the floor issue.



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I don't and wont say you can't but I would just wouldn't recommend either. I disagree with the laminated stand being inferior to steel as I think both have their merits. The steel would still need to be shimmed more than likely on the basement floor.

 

[grouper therapy]

I built this stainless steel " appears floating" stand using lvls and was rock solid.
I built the structure for the radius cornered one out of single layers of 3/4" plywood on edge . The floor underneath was concrete and was some kind of bumpy. It sits in a high rise in midtown. My design for it had to be approved by the property owners' structural engineer and the building designer as well.
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[ghbrewer]

Those are some nice looking stands, I really like the first one.


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[rdnelson]

ghbrewer;1050410 wrote: Those are some nice looking stands, I really like the first one.


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Ditto!!! That first
One is the cats meow

 

[outdrsyguy1]

Well thanks for the input guys. I spent all last night looking around at pics of fish tank stands but honestly after looking at hundreds of tanks I found only a couple that were made of anything other than dimensional lumber or even cinder blocks. So I changed everything to 2x6s and lapped all the posts (added a bunch more posts also). Ran some calculations and added some more braces and a skirt. It's built to hold 550 pounds per square foot with zero flex. Had one hell of a long day putting it together today but it's done and rock solid. I could break dance on this thing and it doesn't budge a millimeter. Here's the final.

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And here's one before I added a bunch more bracing and cross members.

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[grouper therapy]

Neat job but just so you know all the horizontals only have a shear and load rating for the screws that you used. For the horizontals to have any load rating any where near their capabilities there must be verticals underneath them to transfer load to the floor. As is the verticals are basically the only load bearing pieces. I would definitely add verticals under those horizontals.
Your about to put around 4 TONS of that. How did you come up with the 550 lbs psf calculation? Like I said a very neat job, My hat off to you . But honestly you could have used 39" tall 2x4 stud walls and ended up with a higher load rating. You only would have to beam across you sump opening. Hope you are not offended just being honest . In the least though I highly recommend those additional verticals.

 

[outdrsyguy1]

screws are terrible with shear strength. I only used them to fasten, everything with any shear/load was done with nails. There's a boatload of nails in this lol.
I used a combination of the pine span tables and some calculators. I approached it several ways, one way with a joist span equal to my span (like 24" OC or 16" OC), then i also looked at each span between supports and calculated the pounds per square foot and converted it to pounds per linear foot for the span tables assuming all the load in that area went to that "beam". Even though it's spread around the surrounding beams.
Also, the posts/legs are flush with the top and go directly to the floor so they will support the weight, the joists and cross members are mostly there for stiffening and support as you get away from the posts. There are some where between 30 and 32 posts/legs that each can carry 4,000 lb's+ at 32" height and the posts are spread all over the base.
https://courses.cit.cornell.edu/arch264/calculators/example7.1/index.html">https://courses.cit.cornell.edu/arch264/calculators/example7.1/index.html</a>

for spans and loading I played extensively with the following:
[IMG]http://www.awc.org/codes-standards/calculators-software/reversecalc">http://www.awc.org/codes-standards/calculators-software/reversecalc</a>
[IMG]http://www.awc.org/codes-standards/calculators-software/spancalc">http://www.awc.org/codes-standards/calculators-software/spancalc</a>

Most of the spans are only about 2'-5" max except the one over the very back where the leg is removed for sump access. That span is 5' and has a laminated 2-2x6 beam
also referenced:
[IMG]http://www.southernpine.com/app/uploads/AL_21-26L.pdf">http://www.southernpine.com/app/uploads/AL_21-26L.pdf</a>

If you think i'm way off on calculations i still have plenty of time to fix things before tank/water gets here.

 

[ghbrewer]

Oy Vey...


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[grouper therapy]

I think your post calculations are probably close. Your beam calculations are really irrelevant due to the load has been transferred to the fastners. Will the stand support the tank probably, with the beams correctly supported it will definitely support it.
How did you determine how flat (not level)it is?

 

[ghbrewer]

Grouper is right, you are HEAVILY relying upon the strength of your fasteners, not something I would personally feel comfortable with. I would also suggest that you put vertical supports under each beam. Just like Grouper, I am curious as to how you measured for flatness?

 

[outdrsyguy1]

I'm not exactly sure exactly what you mean about flatness but before we put the plywood on top we used the level in all directions all over the top and eyeballed the individual joints at the top where the beams and posts came together. It's pretty easy to look and rub your finger across the top and feel any changes in elevation between the members. There were a couple posts that stuck up maybe 1//16 an inch past the beams but I went back and sanded them all down flat. When the 3/4 plywood went down on top it looked like it would absorb and spread out any small irregularity.
As to the fastener load I tried looking up the shear strength design numbers on nails but I'm not so clear on that. It looked like around 80-100 pounds per nail. Have a link or know if that's ballpark correct?
If I'm careful with my cuts I should be able to cut more posts and slip them underneath the beams between the beam although it's hard to imagine it would make much difference as its only 1.5" away from a post that already runs top to floor. Maybe if deflection caused the beam to load up before the post I could see the fasteners taking most of the load.

 

[Adam]

Grouper and Brewer are correct. While you do have a lot of columns the beams have none other than the fasteners. I see you laminated most of the 2x4's, one of them should be under the beam at each location.
I sell construction fasteners for a living and I wouldn't rely on them in this instance. Also I might have used a bottom plate of pressure treated for the whole structure to sit on.

 

[Adam]

Also the more I look at it I think over time you will have pressure points on each of your columns without supporting the beams from underneath.

 

[outdrsyguy1]

Okay so I just counted and there are over 170 nails across the posts (probably more like 200 but I only counted the ones I could see/knew about, also didn't count any of the screws). At 80 pounds per nail that's 13,600 assuming all weight went to the fasteners.
I was a little worried about pressure points at the posts too anit. It really should be no biggie at all to snug fit 2x6s and laminate them to the posts such that they support the beam at each post. I'll start working on that tonight.
Thanks all
Also fyi it's all 2x6 and not 2x4.

 

[ghbrewer]

Right, each and every vertical support location needs to have support directly beneath the beam. See schematics:
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[outdrsyguy1]

Thanks grant. Didn't think about doing one at each corner since there's a 1.5" overlap from the side beam but makes sense your way.

 

[outdrsyguy1]

Actually, in some spots a 2x4 fits a lot better. That would still be plenty strong as a 27" tall column right?

 

[ghbrewer]

Research winding sticks for checking for flatness... It is hard to tell if there is a twist using levels.

 

[ghbrewer]

outdrsyguy1;1050635 wrote: Actually, in some spots a 2x4 fits a lot better. That would still be plenty strong as a 27" tall column right?

Better than nothing, just make sure that it touches both the beam and floor squarely. Might require some sanding or careful cutting to get it to fit and touch squarely. Be careful they are not too short and/or not too long, it must be a precise fit.