henward Posted February 1, 2013 Report Share Posted February 1, 2013 Ok, tank and water will be approx 2tons, a little less actually but say 2tons round figure. i am thinkng, 8 or 10 legs, reinforced of course for lateral pressures. the bottom of the tank will be supported with plenty of support. i was thinking a support every 30cm or so. so plenty. lookng at 25mm square tube 2mm or 3mm wall thickness. Quote Link to comment Share on other sites More sharing options...
livingart Posted February 1, 2013 Report Share Posted February 1, 2013 the thicker the wall the more strength 50mm RHS will allow bigger spacing http://www.steelnorthshore.co.nz/index. ... _1039_1069 Quote Link to comment Share on other sites More sharing options...
David R Posted February 2, 2013 Report Share Posted February 2, 2013 I just asked MFK a similar question; http://www.monsterfishkeepers.com/forum ... glass-tank Here are the few options I'm looking at after talking to an engineer friend; After doing that awesome and incredibly accurate drawing using the latest hi-tech computer software (MSPaint...) we decided to add a centre brace on the bottom regardless of the design. No its not to any scale, just a crude sketch to show the different leg/top configurations. As for materials; 50x50x3mm, or 50x50x4mm, or 65x65x3mm, about a $50=gst increase in cost between each. The larger square will be more rigid against lateral movement, but possibly a bit overkill? I'm not going to add in any diagonal bracing as the stand is only 400mm high and we don't really get many earthquakes up here. So, Option A involves less welding and looks cleaner (and is how the stand for my 1400L tank was done, in 40mm sq), but means each leg is supporting ~350kg Legs are 1200mm apart which is the same as the front-to-back span. Option B has more legs and more support, but uses more material and more welding makes it more difficult to keep it dead straight. May also be a bit overkill? Legs only 600mm apart and each supporting ~220kg. Option C seems like a good in-between, legs 800mm apart and 275kg each, but unless more horizontal supports are added it leaves an area of 1100x730mm supported only by the 25mm ply I plan on putting on top. Is this ok with 15mm glass? Not sure... Quote Link to comment Share on other sites More sharing options...
henward Posted February 2, 2013 Author Report Share Posted February 2, 2013 I am opting for way more middle bars supporting the base.. Not using ply just poly I am thinking 8 to 10 legs See what the guy says who will design it. Quote Link to comment Share on other sites More sharing options...
David R Posted February 2, 2013 Report Share Posted February 2, 2013 Yeah its a bit of a trade off eh, Thinner material and more legs = more even support, thicker material and less legs = more rigid, thicker material AND more legs = heavy and expensive... I'm leaning towards option B and 50x50x3. Get a price for me too, will see how it stacks up with my guy up here. Quote Link to comment Share on other sites More sharing options...
F15hguy Posted February 2, 2013 Report Share Posted February 2, 2013 medium material + medium bracing = medium cost??? Quote Link to comment Share on other sites More sharing options...
Warren Posted February 2, 2013 Report Share Posted February 2, 2013 A tank this size could be over 2000kg. If you use gravel to a depth of 75mm that alone will be around 750kg... 25mm tube is way too small. The strength of the tube is fairly linearly proportional to the thickness of the wall - eg, you double the wall, it's twice as strong. The strength based on tube size is close to a cube law in strength however. If you double the overall width (say 25mm to 50mm) it's close to 8 times stronger. For a tank this size I would use 75mm x 50mm x 3mm RHS as a minimum and it would need to be supported by a vertical leg every 600mm minimum + have appropriate diagonal bracing. Under the tank I would run a front to back member of the same size every 600mm as well (so to line up with the legs). You may also need a row of legs along the middle of the tank (not just front and back). I'd also put diagonals between the front to back members for stabilty and extra support. You will need about 50mm thick board under the tank - something like tri-board. I would simple fix this to the steel frame with no-more-nails. You put the no-more-nails on the steel, sit the single sheet of tri-board on top, place about 12mm poly on top and then sit the empty tank on top of this. This will force the board to conform to the shape of the tank bottom and the glue will act as a filler between the wood and steel as you will never get the steel stand perfectly straight or level. Good luck with anything smaller - come talk to me after and good sized earthquake and then we'll see if this was overboard... Quote Link to comment Share on other sites More sharing options...
alanmin4304 Posted February 2, 2013 Report Share Posted February 2, 2013 Chrstchurch may be called shakey town now but be aware that we live in a shakey country and you cannot rely on your place not getting a decent shake one day. People down this way are a lot more conscious of shakes when building stands after seeing the mess that a shake can make. I would suggest you brace the hell out of it and research the best way to secure the stand and tank so it does not topple over. Quote Link to comment Share on other sites More sharing options...
Warren Posted February 2, 2013 Report Share Posted February 2, 2013 I went away from all-glass tanks for this very reason some time ago. I'll only go with steel frame tanks with the base integrated into the design. This way the glass is pressing into the silicone at the joints and the water pressure actually helps keep things together. The silicone is no longer a structural component of the aquarium and becomes only a sealant and virtually all the strength comes from the steel and other composite components making up the complete tank. The tank can also be secured to the floor with bolts or put on an isolation platform - whichever is your preference. Having a well braced stand will not stop the tank shaking apart however and the silicone is about as likely to tear as the glass to break in a good shake on a tank this size... When you do build a stand that properly supports the tank (almost no flex) so the bottom glass is evenly supported you will also have built a stand that will resist earthquakes as a side effect... Quote Link to comment Share on other sites More sharing options...
henward Posted February 2, 2013 Author Report Share Posted February 2, 2013 I went away from all-glass tanks for this very reason some time ago. I'll only go with steel frame tanks with the base integrated into the design. This way the glass is pressing into the silicone at the joints and the water pressure actually helps keep things together. The silicone is no longer a structural component of the aquarium and becomes only a sealant and virtually all the strength comes from the steel and other composite components making up the complete tank. The tank can also be secured to the floor with bolts or put on an isolation platform - whichever is your preference. Having a well braced stand will not stop the tank shaking apart however and the silicone is about as likely to tear as the glass to break in a good shake on a tank this size... When you do build a stand that properly supports the tank (almost no flex) so the bottom glass is evenly supported you will also have built a stand that will resist earthquakes as a side effect... Warren. I was thinking no ply just poly under the tank. I would have supports going across under tank quite a bit.... Maybe every 30cm apart... Or less... Thoughts? Quote Link to comment Share on other sites More sharing options...
Warren Posted February 2, 2013 Report Share Posted February 2, 2013 Thick about for a second - divide the surface area of the tank bottom by the surface area of the stand members and this ends up as the multiplier for force on the poly... A tank of 2400mm x 1200mm = 2880000mm² If the stand has 50mm wide top members spaced at approx 300mm this means 9 members 1100 long + 2 across the front at 2400 long so; 9 x 1100mm x 50mm + 2 x 2400mm x 50mm = 495000mm² + 240000mm² = 735000mm² so the multiplier is 2880000 / 735000 so approximately 4. If the tank weighs 2000kg this equates to 2000/2880000 = 0.6944g/mm² so basically nothing. If there is no bottom support it will be 2000/735000 = 2.72g/mm² so 4 x as much. You would need to see if this loading short-term and long-term will cause the poly to crush so the metal directly contacts the glass. Adding a decent thickness of laminated wood under the tank helps the bottom glass significantly and lowers the loading on the poly. Quote Link to comment Share on other sites More sharing options...
henward Posted February 2, 2013 Author Report Share Posted February 2, 2013 Also warren I was thinking of building tank on site and on the stand.. Reason is that ccan't be lifted easily and too heavy. How do i do the no more nails approach? Was thinking 40mm poly under tank so still think ply? Is it better to have thicker ply and thinner poly, thinner ply thicker poly? Or equal thickness? WWhatthickness ccombo would you do? Quote Link to comment Share on other sites More sharing options...
Warren Posted February 2, 2013 Report Share Posted February 2, 2013 For some reason people think poly fixes up all erros in a stand design. From my previous post you can see the poly has almost no load on it if the stand is properly designed so it will not deform to take up errors. It's important to get the stand correct. Therefore 40mm poly will do nothing more than 10-12mm poly. As previously stated, 50mm minimum composite under the tank if supported as you suggest... Ply would be ok (2 x 25mm marine ply) or 50mm tri-board. The only purpose the poly serves is to take up very small point-loads like a slightly proud screw head or a piece of grit you missed when cleaning the stand or bottom of the tank. Other than insulation and point-loads it serves almost no other purpose. Quote Link to comment Share on other sites More sharing options...
henward Posted February 2, 2013 Author Report Share Posted February 2, 2013 For some reason people think poly fixes up all erros in a stand design. From my previous post you can see the poly has almost no load on it if the stand is properly designed so it will not deform to take up errors. It's important to get the stand correct. Therefore 40mm poly will do nothing more than 10-12mm poly. As previously stated, 50mm minimum composite under the tank if supported as you suggest... Ply would be ok (2 x 25mm marine ply) or 50mm tri-board. The only purpose the poly serves is to take up very small point-loads like a slightly proud screw head or a piece of grit you missed when cleaning the stand or bottom of the tank. Other than insulation and point-loads it serves almost no other purpose. Oh ok. Tri boards or marine ply is easy enough. Can i still use this approach with no nails but build tank on it? Do i need no nails? Was thinking.. . Mdf is soft to a degree..... Should this conform and level out stand inconsistencies? Or is the no nails approach supreme? Quote Link to comment Share on other sites More sharing options...
Warren Posted February 2, 2013 Report Share Posted February 2, 2013 The surface of the board is relatively flat. It must NOT conform and remain perfectly flat so it's perfectly aligned to the bottom glass of the tank. Only then will there be relatively even pressure over the entire surface between the glass and wood. The no-more-nails acts as a filler and will vary in thickness and take up the errors in the stand construction. The support under the glass must perfectly match the tank. If you screw or fix the board other than using glue as a filler and let the board sit naturally with the tank on it then is will not be matched to the bottom of the tank and there will be high-pressure points under the tank - even with poly (of any thickness) between the glass and board. Don't cut corners with big tanks and big stands! Quote Link to comment Share on other sites More sharing options...
henward Posted February 2, 2013 Author Report Share Posted February 2, 2013 The surface of the board is relatively flat. It must NOT conform and remain perfectly flat so it's perfectly aligned to the bottom glass of the tank. Only then will there be relatively even pressure over the entire surface between the glass and wood. The no-more-nails acts as a filler and will vary in thickness and take up the errors in the stand construction. The support under the glass must perfectly match the tank. If you screw or fix the board other than using glue as a filler and let the board sit naturally with the tank on it then is will not be matched to the bottom of the tank and there will be high-pressure points under the tank - even with poly (of any thickness) between the glass and board. Don't cut corners with big tanks and big stands! Ok good to know. as for my question of building the tank ON the stand, how will that come into play? can i do that? glue, wood, poly then put the base of the tank on it and commence to build the tank? will that have the same effect? no nails dry quickly, so i dont want it to dry too hard before it gets the full force of the tanks weight to compress the glue and even it out to match the stand/wood surface. any feedback on that? Quote Link to comment Share on other sites More sharing options...
henward Posted February 2, 2013 Author Report Share Posted February 2, 2013 Also should the piece be one piece or can it be 2 pieces? Sheets I think come in 2400x1200x650 I think but just in case.... Does it matter? Quote Link to comment Share on other sites More sharing options...
David R Posted February 3, 2013 Report Share Posted February 3, 2013 For a tank this size I would use 75mm x 50mm x 3mm RHS as a minimum and it would need to be supported by a vertical leg every 600mm minimum + have appropriate diagonal bracing. Under the tank I would run a front to back member of the same size every 600mm as well (so to line up with the legs). You may also need a row of legs along the middle of the tank (not just front and back). I'd also put diagonals between the front to back members for stabilty and extra support. You will need about 50mm thick board under the tank - something like tri-board. I would simple fix this to the steel frame with no-more-nails. You put the no-more-nails on the steel, sit the single sheet of tri-board on top, place about 12mm poly on top and then sit the empty tank on top of this. This will force the board to conform to the shape of the tank bottom and the glue will act as a filler between the wood and steel as you will never get the steel stand perfectly straight or level. All I'll say is thank christ you don't come up with the building code for houses... Quote Link to comment Share on other sites More sharing options...
henward Posted February 3, 2013 Author Report Share Posted February 3, 2013 All I'll say is thank christ you don't come up with the building code for houses... haha :sml1: I am in no doubt though that the stand will be extremely sturdy! and survive the next mass extinction Quote Link to comment Share on other sites More sharing options...
David R Posted February 3, 2013 Report Share Posted February 3, 2013 Jokes aside, does this mean that every single aquarium stand I've ever seen, with the exception of that nearly-immovable timber/MDF behemoth Henward bought off Warren, is grossly under-built and an accident waiting to happen? The value of 3.8 is based on statistical analysis of aquarium failures in the USA and Europe (not NZ shakey-land). It's used by all commercial suppliers of large public displays as it ensures public safety is met. I don't know the statistical value of tank failure when a tank is built with a safety factor of 3.8 but it will be a pretty small number if it's based in the US. So if 3.8 is the "industry standard" safety factor for tanks in the US/Europe, why do none of the commercial stands I've ever seen come anything close to what is suggested above (including California, which is about as earthquake prone as NZ)? 10x4x3', 770g acrylic tank, stand is made of 50x50x3mm steel, 5 pairs of legs and a few diagonals, owner is in the Bay area of CA so certainly not immune to earthquakes. Obviously it takes a lot less that described above by Warren to support a 2000L tank under normal conditions, though you certainly want more than the bare minimum so the stand will be able to withstand a certain degree of sideways loading. But compared to the example above that is obviously able to support nearly double that, is there much point in building a stand that will out-last your house in the event of a massive earthquake? Quote Link to comment Share on other sites More sharing options...
henward Posted February 3, 2013 Author Report Share Posted February 3, 2013 Jokes aside, does this mean that every single aquarium stand I've ever seen, with the exception of that nearly-immovable timber/MDF behemoth Henward bought off Warren, is grossly under-built and an accident waiting to happen? Nice tank! So if 3.8 is the "industry standard" safety factor for tanks in the US/Europe, why do none of the commercial stands I've ever seen come anything close to what is suggested above (including California, which is about as earthquake prone as NZ)? Nice tank 10x4x3', 770g acrylic tank, stand is made of 50x50x3mm steel, 5 pairs of legs and a few diagonals, owner is in the Bay area of CA so certainly not immune to earthquakes. Obviously it takes a lot less that described above by Warren to support a 2000L tank under normal conditions, though you certainly want more than the bare minimum so the stand will be able to withstand a certain degree of sideways loading. But compared to the example above that is obviously able to support nearly double that, is there much point in building a stand that will out-last your house in the event of a massive earthquake? Quote Link to comment Share on other sites More sharing options...
henward Posted February 3, 2013 Author Report Share Posted February 3, 2013 Nice tank Quote Link to comment Share on other sites More sharing options...
David R Posted February 3, 2013 Report Share Posted February 3, 2013 you know there's an edit button eh? :sml1: Quote Link to comment Share on other sites More sharing options...
henward Posted February 3, 2013 Author Report Share Posted February 3, 2013 you know there's an edit button eh? :sml1: Yes Quote Link to comment Share on other sites More sharing options...
F15hguy Posted February 4, 2013 Report Share Posted February 4, 2013 I always assume an earthquake, thats why my 3ft tanks are all on 4x2 stands with diagonal bracing. then again, Auckland is more likely to have a lava apocalypse than an earthquake spree... (dumbasses building ontop of that.....) Quote Link to comment Share on other sites More sharing options...
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