precautions of going larger...

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Jcarlilesiu,

I reread my post, and I didn't explain myself properly. I was referring to exceeding a load limit by lets say 50%, over a 1 square foot area, VS 25% over a 10 square foot area, for a given room size. You said there's no mandated safety margin, so that answers my question. The reason I asked, is because there is something similar with aircraft. I know this entire post doesn't really relate to the topic, I just wanted you to see where I was coming from.

I'm not an engineer, but I do know my way around an airplane. In aircraft design limits, aircraft have to be certified for a certain load factor (G force), depending on the category the airplane will be operated in. There is also a set safety margin the airplane must meet. Generally, it's 1.5 times the load limit for that particular category. For example, a normal category airplane needs to be able to maintain structural integrity up to 3.8 G's, and at it's maximum certified weight. To be certified for 3.8 however, it must actually withstand 5.7 before failing. That margin of safety is basically meant to allow for unforeseen circumstances, like an in flight emergency or unnoticed structural problem.

The other trick is that many normal category airplanes can actually be operated in the utility category provided certain conditions are met. The utility category gives G limits up to 4.4, and also increases the safety margin to 6.6 G's. The trade off is a given airplane will have a lower certified weight for the utility category. Basically, you're putting a more concentrated load on parts of the airplane by maneuvering harder, but you compensated by lowering the overall weight of the plane.
 
Jcarlilesiu,

I reread my post, and I didn't explain myself properly. I was referring to exceeding a load limit by lets say 50%, over a 1 square foot area, VS 25% over a 10 square foot area, for a given room size. You said there's no mandated safety margin, so that answers my question. The reason I asked, is because there is something similar with aircraft. I know this entire post doesn't really relate to the topic, I just wanted you to see where I was coming from.

I'm not an engineer, but I do know my way around an airplane. In aircraft design limits, aircraft have to be certified for a certain load factor (G force), depending on the category the airplane will be operated in. There is also a set safety margin the airplane must meet. Generally, it's 1.5 times the load limit for that particular category. For example, a normal category airplane needs to be able to maintain structural integrity up to 3.8 G's, and at it's maximum certified weight. To be certified for 3.8 however, it must actually withstand 5.7 before failing. That margin of safety is basically meant to allow for unforeseen circumstances, like an in flight emergency or unnoticed structural problem.

The other trick is that many normal category airplanes can actually be operated in the utility category provided certain conditions are met. The utility category gives G limits up to 4.4, and also increases the safety margin to 6.6 G's. The trade off is a given airplane will have a lower certified weight for the utility category. Basically, you're putting a more concentrated load on parts of the airplane by maneuvering harder, but you compensated by lowering the overall weight of the plane.


I understand what you are saying but I would have a hard time comparing structural integrity of a building similar to that of an airplane which discusing exceeding design limits. The types of design methodology are so different, as well as the types of forces which impact the design.

Building focus basically on two types of loads. Dead loads, which is the members of the building themselves, and live loads, everything else. Live loads can be things that can move around like people and furniture, to other things like wind.

I would not recommend anybody exceed the intended live load of their building because of a percieved safety factor. I think that is just asking for trouble.

The only point I am trying to make here is that I think people have somewhat of a mis-conception about the limits of buildings. People know not to take a car at 120 mph around a hairpin turn, and they know they can't jump and down on things without breaking them. Those simple principles hold true to buildings as well. I have come across many people who think that they would be fine if they parked their car in their living room.

Fact is, buildings, like anything else, have limits as well. We design those buildings for worst case scenarios, but we can't foresee or financially afford to make them bullet proof. Trade Centers case and point.

Buildings have limits, and some of the aquariums being bought and built out there are pushing the limits of that design. When buildings collapse, and people get hurt, it makes the news since its so rare. I am just trying to make everybody aware that buildings aren't invinsible.

I am happy to help consult anybody who may have concerns.

Jake
 
I agree that the article is well written and does a good job of explaining basic principles of structural engineering and how aquariums relate. I don't however agree with everything said.

The idea that you can count on safety factors designed into the floor framing to base the size of aquarium suitable for an area is dangerous. Point loads like an aquarium are tricky.

Theoretically, based on the article, the author makes it sound like you can take the gross design load in any room and concentrate it under the aquarium safely. In a very large framed area with 40-60 pounds PSF, that could represent a lot of weight. Consentrating that weight under a small footprint of an aquarium is spelling disaster safety factor or not.

My point here is not to argue but to offer up advice to anyone that needs it. I am an Architect and have been designing residential buildings for some time. I think the author did a good job, better than I am doing posting on my blackberry, and I think everybody should read it to. Just don't take it as gospel.

Jake
 
Wow, amazing info. This is exactly what i was looking for. But this would not apply with a 1 story house with a foundation would it?

Here is a side question, how would you go about WERE to reinforce the floor if it needed it?

no not usually as they mostly have concrete foundations (the ones without basements of course). Its what i have in CA.

There are plenty of ways to reenforce the floors, the article posted in this thread gives way to ideas.
 
He actually states that that isn't the case... he says that you should really asses the situation every time and that at 55g and smaller no mater the footprint you can put it anywhere in almost any room... over that size you need to really pay attention to what is under the sub-floor. Also you are best to place it near a load barring wall perpendicular to the floor joists. He also states a lot more so it is really worth reading more then once if you are trying to figure out if a tank can go in a specific location. He also gives good tips on adding support. He doesn't say to count in safety factors he is just informing you that they are there and that they can be mitigated by a flaw in the wood like a knot or a split.
 
He actually states that that isn't the case... he says that you should really asses the situation every time and that at 55g and smaller no mater the footprint you can put it anywhere in almost any room... over that size you need to really pay attention to what is under the sub-floor. Also you are best to place it near a load barring wall perpendicular to the floor joists. He also states a lot more so it is really worth reading more then once if you are trying to figure out if a tank can go in a specific location. He also gives good tips on adding support. He doesn't say to count in safety factors he is just informing you that they are there and that they can be mitigated by a flaw in the wood like a knot or a split.



"According to the building code my house can only support a maximum total load of 40 psf anywhere on the floor."
  • No, the 40 psf is a theoretical uniform design live load over your entire floor. You might have a whole lot more than 40 psf directly under your aquarium, but that's okay because you didn't fill your entire room with aquariums either.
Thats exactly what he is saying here, in the very first response to a myth.​



Then, the very next line he says:​



"So then, if I fill my entire room with aquariums that weigh more than 40 psf, my floor will collapse."
  • No it shouldn't. I said that the 40 psf was a MINIMUM design load and I also said that it is a SAFE load. That means that your floor could be (probably is) stronger than the 40 psf minimum in many places, and it also means that the full safety factor is still there to prevent a collapse.​
I don't agree with this line of thinking. If instructions say don't exceed X, even though the engineers designed in some safety factor, then you should exceed X.​



I understand that you really like the article, and I think that I brings up some good points and wrote a good article. However, I don't agree with either of his responses above.​
 
He isn't stating hard facts... he is saying it "shouldn't" collapse and that the "floor could be stronger than the 40lbs psf minimum in MANY places" Are you saying that you shouldn't walk on a floor because you exceed "X" 220lbs psf...?
 
He isn't stating hard facts... he is saying it "shouldn't" collapse and that the "floor could be stronger than the 40lbs psf minimum in MANY places" Are you saying that you shouldn't walk on a floor because you exceed "X" 220lbs psf...?

Look. I am not going to argue with you. If you want to take what is said in the article as gospel, go ahead. I have been doing this for a long time and have the education and experience to offer up opinions and advice which rival the author. We simply disagree on a couple of aspects.

However, I am not going to argue with you about it. If you want to place an aquarium with a point load on a 2nd story which slightly exceeds the gross uniform design load for that area. Be my guest.

As far as your question above. Being able to walk around without the floor collapsing has little to do with exceeding the design limits of the floor within the safety margin of error. Loads are also transfered laterally. Additionally, walking around is a short duration impact point load, which is much different than a long term live load which exceeds the design limits.

I am uninterested in arguing my position with you though for the sake of simply trying to "out do" somebody. I have nothing to prove, just simply to offer up help to those who may need it.

I am finished responding to the conversation unless its from somebody that has a legitimate question about the issue.
 
Sorry I should apologize. I like to debate as it often helps people to see both sides of an argument and come to an understanding. I didn't mean to offend you.
 
So much jargon in here. I'm glad I can't afford a giant aquarium and have to worry about it.
 
also, P/f2 would refer to the punch through the flooring, and total weight has more bearing on the support structure. yeah, a 210lb guy could stand on a block no problem, but put six of them on six blocks standing in the middle of the floor.

not to mention, if the house was built just prior to the bubble, it may not be close to code.
 
If you place the stand on a heavy 3/4" slab of plywood, say 4' x 8' you will spread the load over 32 square feet. This may or may not be sufficient to spread the weight, depending upon the construction framing. As previously stated, if you are on a concrete slab on the ground floor you should not have to worry. Second-floor framing, however, is a different story. I would follow the architect's advice if you are on a second floor, or over a basement.
 
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