Will my fish tank stand hold the weight?

[Dukeman]

TL;DR Summary

Built the stand for a smaller tank... but decided to use a larger tank...

Tank volume is 768l plus the tank and rock to go inside
2000m x 640mm wide x 600mm high

Stand is made of 35mm square x 3mm wall thickness.
Tank width is the same as the steel frame, notice the tank is not over the end legs.
Wooden top is 50mm thick pined and glued planks...
4x top supports cross ways plus the frame lengths.
At the front I wanted an open span...so added a double horizontal rail.. welded in place...

So what do you think... will this stand hold the weight?
I weleded two rectangles and added middle legs... x 8.. so there is empty box section under each leg transferring the weight down... hmmm800kg tank water
300kg tank - 12mm glass
150kg rock at a guess

8 legs ... of strength..lol

Gut feel is OK... but!

And lastly

 

[Baluncore]

Is it made from steel, aluminium, or maybe plastic tube?
Who certified the welding?
Are you in an earthquake zone?
How are the glass plates joined?

You may have used heavy tube, but you have not used engineering principles to allocate the materials to the structural design. For example, what is the purpose of the ladder structure on the floor?

You need to understand the flexibility of the glass, wood, frame and floor. If the hydrostatic pressure of water is not passed evenly from the glass, through the frame, and then to the floor, then it is likely that the glass will crack. I think you should take bets on whether the glass will crack when you first fill it with water. That may be sudden, but I know of a case where a crack gradually migrating through the glass of a similar tank, until it burst and flooded the floor.

No one here is going to say it is safe, because that would assume a liability. You must hire an engineer if that is what you require.

 

[Ranger Mike]

this may help
http://reefcentral.com/forums/showthread.php?t=1567110

 

[Dukeman]

Actually I am just after peoples thoughts.
Mild steel.. and I welded it.

I have had a fish tank similar size in the same spot years ago, so the floor is OK.
There is a wooden floor that goes in the bottom...

No liability for anyone... just your thoughts and why..
I'm in NZ.. we do not sue people here lol... unless your super rich..
Thanks for your comments

 

[Dukeman]

this may help
http://reefcentral.com/forums/showthread.php?t=1567110

I know this thread well, and understand what they say.
Still I have what I have...maybe I will add wooden feet to the floor under the corners..

 

[Dukeman]

My thoughts were that the wooden top would distribute a lot of the load.
As I said it was built for a much smaller tank...

 

[anorlunda]

No liability for anyone... just your thoughts and why..
I'm in NZ.. we do not sue people here lol... unless your super rich..

You misunderstand what a public forum is. Anyone can read this thread, now and in the future. The thread can be discovered by search engine looking for example "aquarium stand". They can conclude that the questions and answers apply to them, and make use of them. Some of them may have little skills and primitive tools. So the thread is not just for you.

 

[Lnewqban]

Copied from
https://www.gns.cri.nz/Home/Learning/Science-Topics/Earthquakes/New-Zealand-Earthquakes

"Historic trends and records dating from the 1840s show that, on average, New Zealand can expect several magnitude 6 earthquakes every year, one magnitude 7 every 10 years, and a magnitude 8 every century."

If you live in NZ, that structure is insufficiently stable to resist lateral seismic loads, while supporting above one ton.

Please, consider these:

That wood plate may look strong and rigid, but you should consider what a slow or accidental water leak could do to that.

Your welds are not stronger than the rigidity of the walls of those tubes.

The assymetrical distribution of the legs mean different bending loads and subsequent uneven deflection of the horizontal members, which will be transfer to the glass.

 

[Filip Larsen]

I have not read the entire thread through but just want to notice that on the pictures above there are no diagonal bars or load-bearing plates visible. If your plan is to not have any of those then the structure will be prone to side-ways collapse once loaded.

 

[Baluncore]

The mass of the water is evenly distributed over the glass floor of the tank, but the legs are at specific points, so can only provide point forces. The structure, between the top of the legs and the glass tank base, should spread the load, without a point concentration of force on the glass.

The steel frame will sag slightly between the leg attachment points. The wooden deck that sits on the sagged frame provides a surface under the glass floor, but wood will change shape over time as it exchanges moisture with the atmosphere, and absorbs spills.

A layer of foam under the glass floor may compress to reduce the greatest force concentrations, but it will not flow to provide a true equilibrium. For that, you would need a sufficient layer of bedding sand, or a more functional non-Newtonian fluid.

Now that the floor is sorted, we can look at the walls. The walls form a box that will be far more rigid than any other component, with the possible exception of the slab floor of the house. Any length-ways wind, or twist in the frame, must match the twist in the glass wall box. It would be an advantage if the top of the frame could flex to follow the glass walls, but that would require the legs not be full height vertical columns. I would look at some form of 2D whippletree that could rock as required, to adjust the load equally over all the legs.

In the short term, without changing the length of the legs, the problem might be resolved by the presence of the layer of bedding sand or non-Newtonian fluid, topped by a layer of foam.

 

[berkeman]

Thread closed for Moderation...

 

[berkeman]

Are you in an earthquake zone?

If you live in NZ, that structure is insufficiently stable to resist lateral seismic loads, while supporting above one ton.

Exactly: https://www.learnz.org.nz/geohazards163/bg-standard-f/earthquakes-in-new-zealand

notice that on the pictures above there are no diagonal bars or load-bearing plates visible. If your plan is to not have any of those then the structure will be prone to side-ways collapse once loaded.

Yes, this structure looks prone to racking and collapsing, perhaps onto the folks admiring the fish in the tank. The resistance to racking can be increased substantially by adding sheer walls:

https://lynn-engineering.com/shear-walls/

OP -- please work with a local Mentor to help you redesign this project to make it safer and limit the chances of collapse and injury. That is not what PF is for.

Thread will remain closed.