question for bridgeman

[therealtoddius]

I am going to get a very large aquarium for my home can you possibly give me some advice. It is a new home sitting on concrete piers with 2x12 floor joist and 3/4" finished plywood flooring with carpet. The floor joist are on 16" centers and the tank will be against a load bearing wall. It is a two story house and the tank will be on the first floor. My quaetion is though with a tank 10' long and 30"-36" wide and 6' tall roughly 1000 gallons plus LR. If I have more piers put under the house where the tank sits do you think it will be a problem. The tank will be sitting on a solid 4" frame covering the whole bottom of the tank. Thank-you for all of your input it is greatly apprieciated.

 

[therealtoddius]

are you there? Anyone else with experience on structural matters?

 

[therealtoddius]

Hello?

 

[bridge man]

First question, is this load bearing wall a block wall or a studded wall? Second question, can you explain the concrete "piers"? The joists will primarily be in shear, and a 2x12 spruce-pine-fir (common material) can handle approximately 788 pounds in shear. In 10', you will have 7-8 joist, depending on how they are spaced under the tank. This means that you will have about 5900 pounds of capacity from the joists. A 1000 gallon tank will be well over that at around 8000-9000 pounds. You will need to beaf up your flooring system. If possible, I would recommend bracing the floor with additional columns and beam at the front edge of the tank. A column at the two ends and the middle with a beam spanning between the three columns. This will roughly double your floors capacity since the extra support will split the weight and put half the shear on the joists at each support, but that will not give you a great safety factor. Another recommendation on top of the extra column and beam, would be to mate additional 2x12's with the existing joists, which will give you a capacity of a little more than twice of what is needed. I think I would sleep well with that kind of safety factor. Sorry it took so long to get to you. I read the boards at work and don't get to read them on the weekends.

 

[therealtoddius]

It is a stud wall. The piers are 8" cinder blocks that are poured and rebared to 24"x24" concrete bases 12" thick set in the ground. The floor joist are on 16" centers and will be running perpendicular to the tank. What size beam do you think I should use?When you say mate extra 2x12 to the existing joist do you mean to just nail another joist to the one that is there and have it span the width of the tank resting on the added beam? Thanks for the info. I do not want to worry about any floor support problems. Thanks so much! Also the tank may only be 750 gallons.

 

[bridge man]

You could frame another stud wall under where the front edge of the tank will be sitting, which will transfer the load directly into the front and back walls. It may not be preferred if this is a finished basement, but you could always turn this into a closet or something like that. This may be easier and cheaper than going with additional columns and a beam. I would recommend sheeting at least one side of the wall to help keep the studs from buckling in compression. By mating, I mean to simply nail another 2x12 joist to the existing ones and have them bear at both ends at least the width of the top plate on the load carrying walls. So they wouldn't have to be that long, maybe 3.5'-4'. For some reason, I am not gettng emails telling me that someone has replied to messages, so it might take a little longer for me to get back to you.

 

[therealtoddius]

We do not have a basement so I will have to go with the extra colums and beam and the extra floor joist bracing. would that be more than sufficient to support the weight?

 

[bridge man]

Is the tank going up against an exterior wall, which would be a block wall running the perimeter of the house? I thought the load bearing wall you were referring to was in the basement. You could build a few more piers, preferably at the corners of the tank and in the middle along the front and back edges. If this is a crawl space, then the columns won't have to be too tall and should be fairly easy to build. The foundations you mentioned will support the weight no problem. Then for a beam, tripled up 2x12's would be sufficient. If you do something like this, then you can mate to every other joist and the system will be sufficient. The thing you want to do is provide enough columns to transfer the load as quickly as possible into them. The more load you have travelling through joists and beams, the bigger they have to be.

 

[therealtoddius]

It ia a load bearing wall for the upstais. The tank will be setting against a ******** wall that runs up along a starway to the second floor.
I am going to go with your advice to mate another 2x12 to the existing 2x12 floor joist that will span the width from one support beam to another one (3 2x12) that i am going to add which will sit on top of 3 more colums. I will proably add some brcing between the floor joist also. All of this is in a crawl space under the house. Building the colums is the only thing I am not sure that I can handle as I want them to be strong enough and the floor to be perfectly level. Do you think this will be sufficient and that 3 mor cloums under the length of the tank (8-10 foot long) will be enough?
Thanks for all of your help.

 

[bridge man]

Three more columns should be plenty, because the compressive strength of the block and foundations is far more than the strength of the wood bringing the load to them. The columns should be no problem to build. The foudations will be even easier. You really don't even need to form them up, just dig them out, tamp the bottom to compress the soil, and use the soil on the sides as the formwork. Laying block isn't much harder, and the good part is that no one will ever see it, so it doesn't have to be pretty. You will probably have to do some shimming once you get to the top just to make sure the support beam is tight between the joists and top of column. I wouldn't mind seeing some pictures as you go along if that is possible.

 

[therealtoddius]

I will try to get some pictures this week to show you what I have right now. The people building the tank for me also want to see what is going on with the support system as it will need to support 8000 to 12000 lbs. depending on which of two tanks I go with. I hope that ground settling will not be a problem down the line. If so I guess I can always have it releveled. Thanks for all of your help I really apprieciate it. I'll get the pictures up as soon as possible.

 

[bridge man]

You're quite welcome. Starting on the 24th, I won't be around for two weeks, so don't get excited if I don't reply. I will try to catch up when I return the second week of December.

 

[fishdogg]

Bridgeman-
I was curious. You seem vaguely knowledgeable w/regards to supports and structural restraints. However, I have noticed some flaws in your theories on occasion. May I ask you who your Statics professor was, if, in fact, you are an actual structural engineer. I only ask because once in awhile, after reading much of your work, I get the impression that you can talk the talk, but maybe not 'walk the walk'. Please prove me wrong. I am looking for answers to my own structural issues, and want to make sure you are the real deal!
Many respects (if you deserve them!),

 

[bridge man]

Could you please point out some of the flaws for me, because if I am wrong, I wouldn't mind being corrected. I am a graduate of Penn State University with a Bachelors Degree in Civil Engineering with an emphasis on structures. Relevant courses include; statics, design of wood, concrete, and steel structures, and foudation design, among others. I currently design bridges and other items like retaining walls in the state of PA. I have worked construction and grown up around construction, because my families company builds bridges for a living. Therefore, I have an understanding of how things work, how loads are transferred, and an idea of what things can hold in reality compared to what they can hold using calculations. Again, please correct me if I am wrong, or the case may be that I am just not picturing correctly exactly what someone may be describing.

 

[fishdogg]

Bridge Man-
Well, I was in fact, happy with most of your replies, but for one example about why I was questioning your skills, was your answer about the plywood support. Naturally, I can understand that plywood is not a structural material, but the big picture here tells me that it must help in some respects to distributing the load. Another flaw I think I noticed was your determination of fatigue points on Steel Plate Girder Bridges, most notably, Structure 7B & 8B in Lebanon County. Do you recall that project, and if so, would you do it differently?
By the way. You've been Punked!!!

 

[bridge man]

Well, I must say, screw you FishDogg. I knew something was up you prick. The next time you go on vacation, you're finished.
Note to others, this prick works with me, two cubes down.

 

[therealtoddius]

I have a few pics on my web site http://www.aquariumking.net
I am going to do it my self. the only question is what to use for shims once I have the columns built and the 6x6 beam in place? Also how do you go about making sure the beam is tight enough? Do I just use a level on the floor joist and new beams? Thanks for all of your help.
You know that revenge is sweet after you've been punked.

 

[bridge man]

You can use just normal cedar shims which are used to shim out doors and windows. Just wedge two shims under the joists in opposite directions so that they pinch/wedge each other in place. With the new supports being so close to the load bearing wall, you shouldn't have to worry about getting them too tight and lifting the floor because the wall will hold the joists down to a point, so get them in there tight. Of course, you will still have to level the stand and aquarium in case the floor is a little out of level. The best bet would be to run the tank with just freshwater for a while and then check for settling and shim/level as necessary. With a tank that big, you don't want any problems which would cause you to have to drain the tank. And finally, I vote for the deep (in depth), 72" tank. If you haven't already, take a look at SteveWeast's tank. It is very deep front to back and gives a nice look.

 

[therealtoddius]

Thanks. The 72" deep is top to bottom.