DIY stand for 360 gal

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grimes135

Aquarium Advice Apprentice
Joined
Nov 14, 2006
Messages
46
hi all,
as some of you know my 135 gal tank broke last week ( the cause is still unknown) anyways i am going to be upgrading to a larger tank. i am concidering going with a 360 gal tank made out of acrylic. the measurements are 8' long 3' deep and 2' tall. i have all tools available and i am knowledgable when it comes to working with wood. i was planning on a stand consisting of 8 4x4s for vertical support spaced every two feet front and back with 4x4 supportbeams going diagonally in between them. and then wrapping it with 1" oak plywood all the way around. Would this be sturdy enough to hold almost 4000lbs of wieght? i have consulted with structual engineers who built my house and the floor will support the wieght so that is not am issue. i like haveing open stands so i would like to incorporate that into my design, and i dont think that would compromise the structual integrity of the stand. if any one has anyexperience with this of happens to know the compression strength of a 4x4 then any input would be greatly apprieciated. also if there is anyway to make my design better please let me know. i am definitely open to any new suggestions. TIA
 
alright... standard disclaimers apply. i'm not responsible if you _____ (fill in the blank with whatever catashtrophe comes to mind). i would highly recommend that you put together a design, and have it reviewed by a competent structural engineer or architect.

that out of the way, from an engineering standpoint, i believe the load bearing capacity of a 4x4 beam (loaded as a column) is pretty high. if i were designing this for my home, i would use two identical frames for the top and bottom of the stand. the legs would sit on top of the bottom frame, and the top frame would sit on top of the legs. i would NOT mount the legs to the inside of the top or bottom frame.

consideration for bending of the top frame "joists" and buckling of the legs (colum buckling) are the two main concerns here.

check this article about replacing load bearing beams in a porch. at the end of the article, it has some equations for determining adequate beam sizes.
http://www.hammerzone.com/archives/framecarp/repair/porch/beam13/replace.htm
i would use the worst case load bearing capabilities that he listed. i would also shoot for a 2X or 3X safety factor. that means, when you determine the required cross-section for your beam, up it by 2 or 3 times. if these are beyond your understanding, dont design a stand for that much weight.

i havent found a good writeup about column sizing, but the eight 4x4 legs *should* have adequate buckling load capacity. whatever you design, it WILL need some sort of bracing. squares will not provide any resistance to collapse. you will need to either cross brace every square opening or use a layer of OSB or plywood to provide some bracing support. again, this should be done over all the square openings.

PLEASE run your deisgn by a qualified individual. paying someone a few hundred dollars for a certified design will be MUCH less than it would cost you to clean up a 360 gallon mess from your home. i was nervous about my 55 gallon stand design, i cant imagine how i would feel designing a 360 gallon tank stand.

~mike
 
It seems like you guys are a ways ahead of me but I cant stop thinking about the added weight onto the homes floor. Are you on a slab or crawlspace? You would be fine on the slab but a crawlspace with subfloor would not be the best,imo. That being said have at it, sounds like a great project! Good Luck
 
beachbumin said:
I cant stop thinking about the added weight onto the homes floor.
i agree with you on this one. i would be extremely hesitant to put that much weight onto a raised floor. even on a slab, that is a large load, and the concrete must be thick enough to handle it.

however....
grimes135 said:
i have consulted with structual engineers who built my house and the floor will support the wieght so that is not am issue.

that said, 4000 pounds seems like an obscene "live load" for a residential design. in this case, that load is applied over 24 sq ft. i hope that the full details of this particular installation have been relayed to the structural engineer in question. there are ways to reinforce the flooring to handle these loads, but i really dont want to get into that...

keep us updated.
~mike
 
mp3z24 said:
that said, 4000 pounds seems like an obscene "live load" for a residential design. in this case, that load is applied over 24 sq ft.
what i say here is a bit misleading. the live load that homes are built to handle is a distributed load over the entire surface area of the floor. residential homes are *typically* built to withstand a minimum of 40 pounds per square foot. the fact that the 4000 lb load is applied over 24 sq ft is irrelevant. the design of the floor and supporting structure is of greater importance.

for those of you interested in a structural engineers explanation of the whole "aquarium on a wood floor" issue, take a look at this link:
http://african-cichlid.com/Structure.htm

it is a good read and give a lot of real information and debunks a lot of typical answers that you see in almost any fish forum.

~mike
 
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