Any engineers out there? Stand without center brace for 210

mphammer

mphammer

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While building my stand, I have been trying to figure out formula's to calculate load bearing this and truss support that. In the end I just ended up overbuilding as much as I could. But short of having a structural engineer look at it, I don't know how to confirm it will hold.
Pics and video below.
Entire frame is built with 2x6, with the exception of 2x8 front rail

IMG_6836.JPEG
IMG_6834.JPEG

 
A couple of notes— though I am an engineer, this advice should not be construed as legal or certified/stamped engineering plans:

- your weakness right now is in fasteners. You should be using lag bolts to attach the wood for the load your tank will require (1,800+ lbs for a 210gal tank)

-you should use consistent size wood for all your beams (aka the outer wood that connects to the vertical columns/legs). Using a 2x6 for 3 sides and 2x8 essentially negates the extra width of the 2x8.

- Id suggest following guidelines for building a deck, as the tank will have a heavy dead load. You can calculate load weights based on that, with on-center distance calls for a 2x6 joist.

- Given the amount of weight, I’d strongly advise using 4x4 columns/legs to hold the weight in the four corners.


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Bhmann said:
A couple of notes— though I am an engineer, this advice should not be construed as legal or certified/stamped engineering plans:

- your weakness right now is in fasteners. You should be using lag bolts to attach the wood for the load your tank will require (1,800+ lbs for a 210gal tank)

-you should use consistent size wood for all your beams (aka the outer wood that connects to the vertical columns/legs). Using a 2x6 for 3 sides and 2x8 essentially negates the extra width of the 2x8.

- Id suggest following guidelines for building a deck, as the tank will have a heavy dead load. You can calculate load weights based on that, with on-center distance calls for a 2x6 joist.

- Given the amount of weight, I’d strongly advise using 4x4 columns/legs to hold the weight in the four corners.


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Click to expand...
Thanks for the quick reply and the info!
-Regarding 4x4 posts- If you look in the pics, each corner has 2 2x6's, and 2 2x4's. It forms a 4x8. Is that not the same or better than a 4x4 post?
-The entire top frame rectangle is 2x6, but the front has an additional 2x8 ran along the 2x6. My thought process was the front has no center brace so its like a load bearing beam, where the rear has a 4x6 (2 2x6's) center support.
 
mphammer said:
Thanks for the quick reply and the info!
-Regarding 4x4 posts- If you look in the pics, each corner has 2 2x6's, and 2 2x4's. It forms a 4x8. Is that not the same or better than a 4x4 post?
-The entire top frame rectangle is 2x6, but the front has an additional 2x8 ran along the 2x6. My thought process was the front has no center brace so its like a load bearing beam, where the rear has a 4x6 (2 2x6's) center support.
Click to expand...

If you’re using better bolts for attaching the beams to the legs, the 4x8 solution should work. My biggest worry is the vertical shear from connecting the beams to those posts. 210gallons is not a light amount of weight.

I’d also make sure the floor that this will be sitting on is solid. 400-500lbs of point weight in each corner is not a small load. I’d suggest checking out this article and consider adding a 4x4 rectangular base to distribute more of the load: http://www.african-cichlid.com/Structure.htm

On the 2x8 front: Load bearing beams don’t quite work that way— there is more to the design (including fasteners to the columns) and you’d likely want a wider beam... but I can’t specifically tell you what width without a more detailed drawing.


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Bhmann said:
If you’re using better bolts for attaching the beams to the legs, the 4x8 solution should work. My biggest worry is the vertical shear from connecting the beams to those posts. 210gallons is not a light amount of weight.

I’d also make sure the floor that this will be sitting on is solid. 400-500lbs of point weight in each corner is not a small load. I’d suggest checking out this article and consider adding a 4x4 rectangular base to distribute more of the load: http://www.african-cichlid.com/Structure.htm

On the 2x8 front: Load bearing beams don’t quite work that way— there is more to the design (including fasteners to the columns) and you’d likely want a wider beam... but I can’t specifically tell you what width without a more detailed drawing.


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Click to expand...
But the bolts or screws shouldn't really play a factor in it bc the load should all be transferred from the top frame to the load bearing posts then to the bottom frame and then into the floor.
 
There is load that the screws will carry where each cross beam/joist is attached and where the 2x6 connects to the posts. It’s not identical at all connections, but typical #6 or #8 screws won’t handle the distributed weight of 1800lbs— it’s why joist hangers and straps with high rates nails or bolts are used when supporting heavy loads like this tank.


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Bhmann said:
There is load that the screws will carry where each cross beam/joist is attached and where the 2x6 connects to the posts. It’s not identical at all connections, but typical #6 or #8 screws won’t handle the distributed weight of 1800lbs— it’s why joist hangers and straps with high rates nails or bolts are used when supporting heavy loads like this tank.


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Click to expand...
I see what you are saying when it comes to building a deck that is just supported by the hangers that are attached to a beam. But the "beam" in this case is getting support by the outside corners and wherever else he has a load bearing post.
 
Annotation 2020-06-21 190312.jpg

This is what im talking about.....The screws dont really hold any weight of the tank. They are really just there to make sure the wood stays in place.
 
I see it now. I didn’t look closely enough to see the notched post and was assuming it was hung externally on the leg.


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