Let's talk about structural support...

[Chad]

First... My next build (2-300 gallon range) will not be for ~2 years or so, but planning, drawing, replanning and playing with all this stuff makes me happy, so I am thinking about it whenever I have down time to do so. I am sure I will go through at least 87 more iterations before I actually start building... I am collecting some equipment as good deals and opportunities present themselves

 

Also, I know this can be done, it is just a matter of thinking through it, pulling out my calculator, being creative, and perhaps using something beyond wood as a construction material. Safety factors for most stands are super high (which is good, building materials are generally cheap and peace of mind is worth more than cost in most cases with stands).

 

So here we go. One things that always detracts (in my mind anyway) is the massive presence of the stand, especially with larger builds. Often, I see this overcome, quite successfully, by integrating the stand into the house (in-wall, matching cabinetry extended beyond the tank, etc.) I would like my next build to really focus and make the tank itself pop (even before I stock it) in a simple and modern way. One thing that I think will accomplish this, is by minimizing the presence of the stand and giving it a "waist" like this (sorry for the horrible paint picture, I will put a better 3D image together when I get home).

 

 

In regards to the load path (I know there are a bunch of engineers in this group, do we have a mechanical? I can talk neutrons all day long, but I am at a basic level with structural stuff), what is the best way to accomplish this? It seems that something will have to be in combined bending and shear (my least favorite types of stress!), but I think it to be doable and I have some ideas that I will add later.

 

But first, what do you think?

[treesprite]

What kind of material do you plan to use for the skeleton of the stand if not wood? Some folks use wood for large tanks, but with LOTS of re-enforcements.

 

Based on the 1 dimensional drawing, it looks like a typical design. Did you mean it to be more like a pedestal, or just an inch or two narrower than top and bottom frames?

[Coral Hind]

For the stand you need a structural engineer and not a mechanical engineer. Mechanical engineers deal mostly with HVAC and plumbing type stuff.

 

The stand is very doable, you will just need to make sure the horizontal plate is stiff enough or braced with a frame so it doesn't flex any. How far in are you thinking of setting the side panels?

 

 

[BowieReefer84]

For the stand you need a structural engineer and not a mechanical engineer. Mechanical engineers deal mostly with HVAC and plumbing type stuff.

 

The stand is very doable, you will just need to make sure the horizontal plate is stiff enough or braced with a frame so it doesn't flex any. How far in are you thinking of setting the side panels?

 

 

In my previous job I dealt with two structural engineers. Their expertise is light gage metal framing. I am not sure if you would consider this type of framing using a metal coated in G90 and painted to prevent any possible rust. They are both very professional, and good to deal with. I am sure you could build some sort of box header with a steel plate on top.

 

I only read the drawings, and made sure I ordered the right material. I have no clue on calculation of loads . . .

 

The first is Adtek http://www.adtekengineers.com/

 

The second is Sturtural Systems and Solutions (this one would be better to deal with imo) The owner Paul does 95% of the work himself.

2420 Pony Ln

Reston, VA 20191-3915

(703) 391-1044

 

Obviously there would be a cost with their services, but you would have peace of mind with stamped drawings . . .

[Chad]

lol, yea, yea, structural, mechanical... its all the same, right? haha... Like I said, neutrons...

 

I was thinking 6-8" on all sides. So, with a tank footprint of say 60x36, the "skinniest" part of the stand would be 44x20.

 

Wood or steel are probably the two easiest materials to deal with... Anyone know a local who builds steel stuff?

[BowieReefer84]

lol, yea, yea, structural, mechanical... its all the same, right? haha... Like I said, neutrons...

 

I was thinking 6-8" on all sides. So, with a tank footprint of say 60x36, the "skinniest" part of the stand would be 44x20.

 

Wood or steel are probably the two easiest materials to deal with... Anyone know a local who builds steel stuff?

 

You can buy all the material you need from Capitol Building Supply. They have locations around the area, and really great sales people. First you would need a design. With a chop saw and impact driver / drill you can do all the work. A lot of the screws they use in design are self taping and its really not that bad. Just make sure you let the Engineer know that you want all mechanical fasteners NO welding. It should not be an issue.

 

The hardest part would be the top plate. You would likely have to order that to size, which may cost more, but DEF worth it. Also, make sure it would fit through the door. . . .

[BowieReefer84]

Just a thought as well. When you drill into the top plate with hex heads (most likely) the surface would not be flat. You could put plywood with holes countersunk to match the screw layout so your tank would sit flat on the wood. I am just thinking out loud. You did ask for it...

[Charlie]

Chad, I'm sure that you had an erector set when you were a kid. If you're going to use all mechanical fasteners, you may want to drop the extra coin and go stainless (with stainless fasteners). You can find most of the strengths of materials on the 'net and from there fall back on your freshman physics class (or trig) for the appropriate angles. BowieReefer makes an excellent point, though, make sure that it'll fit through your door.

[Charlie]

Just a thought as well. When you drill into the top plate with hex heads (most likely) the surface would not be flat. You could put plywood with holes countersunk to match the screw layout so your tank would sit flat on the wood. I am just thinking out loud. You did ask for it...

You can countersink metal with a hand-held drill, it's just easier with a drill press.

[BowieReefer84]

If the sump is NOT going underneath you could use CMU. Go the extra mile and pack it with rebar and grout . . .haha. OR, do three sides in cmu and put a lintel across the back so a sump fits under . . . LOL

[Chad]

You guys are throwing posts at me so fast that I dont hardly have a chance to think!!! Thanks for that! And thinking out loud is good

 

I just looked at the CBSI website, they certainly have a great selection of stuff in general and list the steel prices online, so that is good!! I think I would want to go with a "mostly welded" approach, where the top and bottom come off of the side pieces. I know that I can get away with pretty minimal vertical support... assuming wood for a second (since I know the number off hand) one 2x4 supports ~10,000# in compressive load. Fitting through the door is one thing that I am designing in up-front, since I want this thing to be 40-44" tall probably. So I was thinking that there would be several parts that are assembled in place.

 

Why no welding? A weld is much stronger in shear than a fastener.

 

As far as the specs and all that go, I have access to all of the ANSI and ASME specs so finding that stuff is easy.

 

I hadnt thought about putting ply on top, that is a good idea and I will probably do something like that.

[BowieReefer84]

 

 

Why no welding? A weld is much stronger in shear than a fastener.

 

 

 

I say no welding because you would have to hire a welder (certified welders don't come cheap) . . .Screws are a lot cheaper, and as long as you follow the PE's plan you are good. Also, you would be able to take it apart a lot easier in the future should the need arise. I know we would always use fasteners at my old company. The drywall mechanics are cheaper than welders. I guess that is my opinion. Either way would be sufficient.

[Coral Hind]

lol, yea, yea, structural, mechanical... its all the same, right? haha... Like I said, neutrons...

I was thinking 6-8" on all sides. So, with a tank footprint of say 60x36, the "skinniest" part of the stand would be 44x20.

Wood or steel are probably the two easiest materials to deal with... Anyone know a local who builds steel stuff?

A 6 to 8" set back is no problem at all. How thick do you want the upper ledge to be?

I'll shot you a PM for a local fab guy.

 

You could put plywood with holes countersunk to match the screw layout so your tank would sit flat on the wood.

That is very good idea.

 

If the sump is NOT going underneath you could use CMU. Go the extra mile and pack it with rebar and grout . . .haha. OR, do three sides in cmu and put a lintel across the back so a sump fits under . . . LOL

Wow, reinforced CMU would be going the permanent route.

[Chad]

wow, CMU, I missed that post! There is a building material that I didnt think about using at all... I wonder how much a CMU stand would weigh... concrete weighs, oh, ~3000 lbs per cubic foot wet, my stand is oh 2 cubic feet... wow!! that'll get er done!!!

 

Imagine that "request for help" thread... Um, guys? I need 30 people to help me move my 6k lb stand into my basement I have chips, salsa, beer, and frags, though... who is in? *cricket, cricket!!

 

In my ideal, the upper ledge (and lower one) would be 6 inches or less, although I have a feeling that will be very material dependent and perhaps material driven.

 

Ahhh, I got you on the welders... Yes, we pay welders a stupid amount of money to get the job done right (although they are often the first to take the fall when something doesnt come out right). I was thinking more of a local fabricator who knows how to weld than someone who is certified to do it and runs though a hand full of NDTs. For my purposes, overbuilding something a bit because I am taking a hit on the structural robustness of a weld probably is more cost effective.

 

I am comfortable doing the calcs myself... just not creative enough (and/or experienced enough to have seen something similar) to come up with the design on my own... I do have some ideas that I will throw out in a little while, though.

[zygote2k]

Arc welding is easy- it just takes a little practice and anyone can do it if they have steady hands.

I'd recommend the welding approach because of the relative ease to build anything out of steel angle.

You could even hang it from the ceiling and have zero stand underneath provided you can build the proper framework to support a few tons.

If you buy the welder now- they are realtively cheap, I can show you how to weld and then you can practice for a few months until you are ready to build the stand of your dreams.

[Chad]

Rob, I can actually stick weld (not well) and tig weld (I think anyone can do that), but dont have space to do even if I have the equipment, that will have to wait until I get out of the city... When I was working on my car a lot I came to the conclusion that welding is something that I would rather pay someone who knows how to make a weld look pretty (something that takes way more skill than I care to obtain)...

 

Here is a better visual of both the "heaviness" of a straight stand and the comparison of a "skinny" one:

 

 

 

 

I havent run numbers on this yet, but I think it will be ok... The "flat" pieces are 2x8s and the joists are 2x4s.

 

As a random side note, by the way, did y'all know that the flex in, say 3/4" glass in a tank with a 3'x6' footprint is close to 1/8"!!!

[CHUBAKAH]

I've built several pedestal type stands for tanks in the past, and what you are looking for is very easy. I can also work up all the calculations structurally speaking for the stand and your home if needed.

 

PM is key.

 

Mark

[Chad]

In rough form (literally and figuratively!!) in wood form, I figure if I can meet all of my self imposed requirements in wood, then I should because I can DIY it.

 

 

 

Thanks Mark! what do you think of this?

 

I appreciate your offer of running numbers, I may take you up on that when the time comes. At the moment, I am looking for the gross concepts and will check for adequacy when I am in a math mood (that happens sometimes too... )

[CHUBAKAH]

The middle section needs some work [little more reinforcement] and the upper and lower section are a little on the overbuilt side. Unless you're just wanting to have the lower section [which may make it tough to put some sort of step stool there to work on the tank] I don't think that part is needed.

 

I haven't looked at the Zero edge site in ages, but you may be able to get some ideas there as most of those set ups are pedestal stands.

 

In any event, I would still base the majority of the load bearing weight on the center section and not on a base if you want that there.

[Grav]

In your drawing, the only thing supporting the ends is the mitered corner of a 2x8... that doesn't look like the kind of support you want. Keep in mind, factory tanks like AGA, Oceanic and perfecto only need support in the corners... and you do not want to be high in the middle.

 

Where are the drain and return lines?

 

I find that "center" overflow boxes really goof up the rockwork.

 

Finally, who is the guy in that picture? I think I went to school with him. :o)

Edited September 21, 2010 by Grav

[FearTheTerps]

I dont think chad is really that far ahead yet in regards to the additional supports or where the drains and returns are going. Considering that earlier this afternoon all he had was a paint sketch. With that said though, I'll ask if you are planning on offsetting the rear of the stand? If you are going to place it against a wall I think that may make it look weird having that extra void there between the stand and wall along with the space you are already going to have between the tank and the wall. Just a thought

[ctenophore]

What about some steel beams (I, H, whatever) laid across a CMU pedestal? The CMU pedestal could be hollow, built in place. If your floor can support the load on a smaller footprint, then you can have much more than 6-8" inset. It should be easy to calculate deflection in the beams.

 

Face the CMU with stone or some other decorative finish and paint the beams Ferrari red with several layers of clear coat. That would be a unique stand.

[Chad]

Thanks, much for the feedback all!! I really appreciate it/ enjoy it.

 

The middle section needs some work [little more reinforcement] and the upper and lower section are a little on the overbuilt side. Unless you're just wanting to have the lower section [which may make it tough to put some sort of step stool there to work on the tank] I don't think that part is needed.

 

I haven't looked at the Zero edge site in ages, but you may be able to get some ideas there as most of those set ups are pedestal stands.

 

In any event, I would still base the majority of the load bearing weight on the center section and not on a base if you want that there.

 

Yea, I realized that the bottom was way overbuilt... for my quick throw-together it was faster to hit the "copy" button for the top which I had already done than do another. All of the horizontal slats on the bottom are unnecessary unless I am forced to put the sump in the stand (something that I am going to try to avoid). I want the step for looks, though, and perhaps for some stability (although I think with a 48x24 footprint it would likely be ok in that regard).

 

I am confident that the four vertical sections are strong enough to support ~550,000 using the compressive strength of SFP lumber (I used white pine) and verifying that the slenderness ratio of the unsupported column is stable using the formula for this on page 203 of the AWCs Wood Structural Design Data. I am using 6000 lbs as a design load (built in FS of 2 using conservative SFP numbers when I would locate dougless fir for this application). Also, I use this as a reference for source wood data. Stability-wise, I am sure there are improvements to be made, either via plywood skin or tensioning wires, since the current stability factor is only in the 0.88 range.

 

In your drawing, the only thing supporting the ends is the mitered corner of a 2x8... that doesn't look like the kind of support you want. Keep in mind, factory tanks like AGA, Oceanic and perfecto only need support in the corners... and you do not want to be high in the middle.

 

Where are the drain and return lines?

 

I find that "center" overflow boxes really goof up the rockwork.

 

Finally, who is the guy in that picture? I think I went to school with him. :o)

 

Thinking out loud here, because this is where the calculation gets complicated and I am not positive how to model it... High in the middle is bad, especially since the tank glass bows downward. In the "first draft" I did last night, the tank is supported on the edges and the main load bearing beams and away from the edges... that is why I sandwiched 2x4s between the 2x8s, I can already see some things that could be improved based on your comments, though... thank you.

 

I think I can bound the problem by creating a matrix of equations that relate various forces using deflections in beams. I thought about modelling the tank as either a distributed edge load or a discrete load applied at the corners (I think the discrete corner load would be more severe). Thoughts anyone?

 

Is it generally true of glass tanks that they only need support in the corners? Is this true for framed tanks and rimless tanks too? I know it would be different acrylic tanks, and I think this problem would be way simpler on an acrylic tank becuase of the more pure distributed load.

 

I was thinking of adding to the modern look by throwing an industrial touch of having the drain and return lines exposed on the back and perhaps paint them a contrasting color or something like that... I dont want a center overflow.

 

The guy in the picture is me lol

 

 

I dont think chad is really that far ahead yet in regards to the additional supports or where the drains and returns are going. Considering that earlier this afternoon all he had was a paint sketch. With that said though, I'll ask if you are planning on offsetting the rear of the stand? If you are going to place it against a wall I think that may make it look weird having that extra void there between the stand and wall along with the space you are already going to have between the tank and the wall. Just a thought

 

I was planning on offsetting the rear of the stand (at least I am right now), I figured I would pull the entire tank out from the wall by 18-24" to really focus on the tank... All of my previous setups have been fun, but most have been all in one stands, canopies, etc. or plumbed to a main sump... but always set against a wall or in a corner or something... One of my design goals for this next setup is to have the whole setup be the focal point and integrated into the design as a whole. (plus, having it out from the wall a bit will make it easier to perform maintenance on).

 

What about some steel beams (I, H, whatever) laid across a CMU pedestal? The CMU pedestal could be hollow, built in place. If your floor can support the load on a smaller footprint, then you can have much more than 6-8" inset. It should be easy to calculate deflection in the beams.

 

Face the CMU with stone or some other decorative finish and paint the beams Ferrari red with several layers of clear coat. That would be a unique stand.

 

That sounds like a pretty cool idea... I think I will play around with it some and see if I can come up with anything that catches me. I know this can be done with steel... I am pretty sure all that would need to be done is to have a steel plate, put a frame on one side to support the tank at the edges and attach it to the pedestal on the opposite side. However, I would prefer to do it with wood so I can make it. In the end, if I cant make numbers come out, I will switch and have it built.

Edited September 21, 2010 by Chad

[Coral Hind]

Chad, Since you want to use wood, look into using some engineered wood products like an LVL beam. They would allow you to do things that are just not possible with regular boards.

[rioreef]

I am no structural engineer, but I did stay at a Holiday Inn before...

 

Seems like the side 2x8s would be the weak point in the design with those 45-degree cuts (think of the locations of where these are fastened). The only real support under those 2x8s is along the inside edge and putting an upward force on whatever fasteners you have on the 2x8s along that side edge because the outer edge is where the tank is putting the downward force the most. The result for the sides is the tank weight is concentrated along that outer 2x4 and there is not much support to carry that load into the rest of the stand. This is not the case for the front and back 2x8s because they have the supported joists to carry the load carry the load across the stand front to back.

 

If the front and rear flat 2x8s were extended all the way to the sides without a 45-degree cut. This would then tie in the corner weight and support needed into those 2x8s that have the joints under them spreading the load out. The remainder side 2x8s would be shorter and loads would be carried better to the front 2x8s.

 

Also, you could double up the 2x4s that are under the top structure and connected to the vertical 2x8s. This would add more support to those 2x8s that are laid flat.

 

Am I seeing this incorrectly?