High Tide Aquatics

AL stand build structural questions

R

richiev

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I'm working on spec'ing out a new tank and stand. The tank will probably be 48in x 24 x 24 +- an inch or two. It will be setup as a peninsula. There are a lot of options in that range, but the main issue I have is I don't want a modern style, industrial, flat panels flush with the tank, painted glossy, stand. That doesn't match anything else I own, and I'd prefer something that looks more like furniture. This IM site picture for instance is closer to what I'd want:

Screenshot_20220916-081408.png


Heading researched options, I really like the idea of a T-slot stand. However, all the examples I've found have been the flush look.

I have no structural engineering design skills, so I'm wondering what my options on building this are. Let's say my ideal is:

• tank is 48in long, 24in wide
• stand is 60in long, 28in wide, 30in tall
• sump under stand

Should I expect the stand to be an AL box the size of the stand, or do I need the AL box to be the size of the tank?

My assumption is the vertical legs need to be approximately under the edges of the tank, and it's better for the legs to be slightly inside the edges of the tank than slightly outside. That'd imply I need to build an AL box 24in wide, 48in long, and then build an outer box surrounding it that the actual tank sits on.

However it'd be a lot easier if I could just build a 60x28 box and set the tank on it.

Anyone have guidance, or know of an AL extrusion stand place that'd give me good advice.

(cross posted to R2R for larger visibility, though I imagine this group has a higher concentration of engineers)
 
I'd definitely have legs and cross members underneath the 4 corners of the tank at 48" or else u have a whole lotta weight and deflection on the horizontal support spans. It would be pretty easy to build a cabinet around that to your spec and style.
 
You’re right, having the legs directly under the tank is best but depending on the size and profile of the aluminum there’s a high likelihood that you could still have the legs pushed out to the 60” that you want. The tank is 48”, so that’s only 6” on either side that is unsupported (if the tank is centered on the stand. If you have a center leg (so 6 total legs) I don’t think there would be a problem.

There are companies that their whole business is building cabinet doors. This is a great option if you want it to match the cabinet doors in your kitchen or office. You’d have to build the face frame around the aluminum frame still and paint or stain it all.
 
Flagg37 said:
You’re right, having the legs directly under the tank is best but depending on the size and profile of the aluminum there’s a high likelihood that you could still have the legs pushed out to the 60” that you want. The tank is 48”, so that’s only 6” on either side that is unsupported (if the tank is centered on the stand. If you have a center leg (so 6 total legs) I don’t think there would be a problem.

There are companies that their whole business is building cabinet doors. This is a great option if you want it to match the cabinet doors in your kitchen or office. You’d have to build the face frame around the aluminum frame still and paint or stain it all
Click to expand...

The length part I'm led concerned about, because my plan there was to build the aluminum (AL) stand to the length of the aquarium, and then handle the extra length through extended boxes. That gives me the option of removing the extra length if I decide I don't like it.

My overall thinking was the overflow end of the peninsula would be a couple inches from the end of the stand, then the aquarium, then an extra 8-10inches on the far end of the stand. It'd look like an aquarium sitting on some furniture, offset from center. I really need to mspaint draw this...
 
Tank side view
PXL_20220916_220432664~2.jpg


Green is the frame
PXL_20220916_220432664~3.jpg


The big question being can I have the vertical legs at the edges of the stand (purple), or do they need to be at the edge of the tank (green).
PXL_20220916_220432664~5.jpg

If they need to be at the edge of the tank I'll just build it flush and not have the side overhang.
 
Flagg37 said:
You’re right, having the legs directly under the tank is best but depending on the size and profile of the aluminum there’s a high likelihood that you could still have the legs pushed out to the 60” that you want. The tank is 48”, so that’s only 6” on either side that is unsupported (if the tank is centered on the stand. If you have a center leg (so 6 total legs) I don’t think there would be a problem.

There are companies that their whole business is building cabinet doors. This is a great option if you want it to match the cabinet doors in your kitchen or office. You’d have to build the face frame around the aluminum frame still and paint or stain it all.
Click to expand...
Oh, also rereading, my original plan if it was 48in was to not have center legs, but I don't care too much either way. I'm assuming if I went beyond 48in I probably need a center leg.
 
H2OPlayar said:
I would sleep better with an aluminum stand and a center leg. Plus a bunch of corner bracing to prevent racking. If going 2" x .125" steel, it can span 48" no problem.


Play with this calculator for square beam calcs.
Click to expand...
That calculator is decent but it does limit your calculations. It calculates a point load right in the middle where as a tank would be a distributed load, and it fixes the supports to the ends of the horizontal beam and only allows two points. You were hoping to calculate the difference with the legs in various locations.

I use an app called skyciv which is a bit more complicated to use but does give you much more flexibility and results. It has a free trial and then yields a much more stripped down version after the trial is up.
 
My concern with having the frame be wider than the tank would have more to do with what material you will have on the top of the stand for the tank to sit on. If you just build a 60" long by 28" wide rectangle, and put a piece of 3/4" plywood on top. Then put your tank in the center of the rectangle, you're expecting that 3/4" plywood to do a lot of work. The frame would *likely* be fine assuming it's made from large enough material, but the plywood may start to sag over time.

You could put pieces of frame across the 28" width to help, but you would be relying a lot on the fasteners for strength.

Another way to look at it though, is in order for the final stand to be 28" wide, the outside dimensions of the frame would be 26-26.5" (assuming 3/4" or 1" thick side panels/doors.) If your T frame is 1.5" wide, that means the inside dimensions of the rectangle is 23-23.5" meaning you would have a slight overhang of the tank onto the frame. Add a little bit of a spacer behind the side panels and you can easily center the edges of the tank on the frame.

For the length, I would probably put the legs even with the corners, and build out a "non load bearing" extension for the extra 12" like you drew a few posts back.
 
Last edited:
Flagg37 said:
It calculates a point load right in the middle where as a tank would be a distributed load
Click to expand...
One thing in structural mechanics they teach is how to turn a distributed load into a point load.

"Conversion of uniform distributed load to point load is very simple. By simply multiplying the intensity of udl with its loading length. The answer will be the point load which can also be pronounced as Equivalent concentrated load (E.C.L). Concentric because converted load will acts at the center of span length."

Types of Load | Explanation | Examples | Load Diagrams | Engineering Intro

There are three types of load i.e, Point load, distributed load and coupled load. Distributed load is further divided into two types i.e, uniform distributed load and uniform varying load....
www.engineeringintro.com www.engineeringintro.com
 
You can convert a distributed load to a point load but it doesn’t yield the same results for its effect on the beam. This is why you lay down on thin ice. Another illustration would be standing on the end of a diving board be laying down along it. The deflection of the diving board is increased when the load is concentrated.
 
Flagg37 said:
You can convert a distributed load to a point load but it doesn’t yield the same results for its effect on the beam. This is why you lay down on thin ice. Another illustration would be standing on the end of a diving board be laying down along it. The deflection of the diving board is increased when the load is concentrated.
Click to expand...
This is true, though I think a point load in the middle represents worst case. So while it may be over built, it should be capable of support.
 
Meshmez said:
My concern with having the frame be wider than the tank would have more to do with what material you will have on the top of the stand for the tank to sit on. If you just build a 60" long by 28" wide rectangle, and put a piece of 3/4" plywood on top. Then put your tank in the center of the rectangle, you're expecting that 3/4" plywood to do a lot of work. The frame would *likely* be fine assuming it's made from large enough material, but the plywood may start to sag over time.

You could put pieces of frame across the 28" width to help, but you would be relying a lot on the fasteners for strength.

Another way to look at it though, is in order for the final stand to be 28" wide, the outside dimensions of the frame would be 26-26.5" (assuming 3/4" or 1" thick side panels/doors.) If your T frame is 1.5" wide, that means the inside dimensions of the rectangle is 23-23.5" meaning you would have a slight overhang of the tank onto the frame. Add a little bit of a spacer behind the side panels and you can easily center the edges of the tank on the frame.

For the length, I would probably put the legs even with the corners, and build out a "non load bearing" extension for the extra 12" like you drew a few posts back.
Click to expand...
good ideas! I did expect to run at least one or two horizontal supports across the width (picture not complete, just showing general layout of base)

Cursor_and_SketchUp.png
 

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