Tank weight on a second-story concrete floor

jstavis

Candiru
MFK Member
Mar 18, 2009
222
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Madison, WI
I've seen a lot of threads about large tanks going upstairs in a wood-framed house, but I was wondering if anyone had any information or insight on concrete floors.
I live in an apartment above a business and my floors are concrete-- my understanding is that concrete strength is measured in thousands of pounds per square inch, which would seem to suggest that it would have no problem holding a several hundred gallon tank. Am I missing something?

I realize that the answer is ultimately going to be "talk to a structural engineer," but if anyone has any feedback then I'd appreciate it.
 

skjl47

Goliath Tigerfish
MFK Member
May 16, 2011
4,397
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Tennessee
Hello; At least one of the following web addresses mentions concrete floors. As with all things it will depend on how the floor was built. If I recall correctly, it seems that some cement floors are similar to wood floors with regard to strength.
(OLD RECYCLEDPOST) Here are some web addresses about floor capacity. The first address is a new one from a post by another Monster Fish forum member a while back. Here are the addresses again with the first being new to the list. Floor capacity depends on a lot of criteria, there is not a simple answer to the question.
This web address is added to the list http://www.cichlid-forum.com/articles/aquarium_weight.php
http://www.ehow.com/how_7485788_calculate-floor-load-capacity.html
The web address above is a site about calculating load capacities of floor joists. They use a formula for the strength of a beam: maximum load in pounds = FBd^2 / 9L.
The width of the wood joist in inches is B (1.5 inches for standard 2 by dimensional lumber.)
The depth in inches is d (7.25 in for a standard 2x8.)(9.25 in for a 2x10)
The distance (span) in feet is L (Unsupported distance)
F is something called the fiber stress when wood bends. It varies with the type of wood but graded lumber will be at least a 1,000 number, some are higher.
They use an example of 2x10 floor joists with a span of 14 feet on 16 inch centers and come up with 1,019 pd for each joist. They figure the area supported by each joist as 18.7 sq ft. They get 54.5 pd per square foot of floor area. I think this includes the weight of the flooring and anything else that is supported by the joists.
I looked at some other sites (Addresses listed below) and found a discussion of static loads and live loads. Two sites describe how to measure the deflection of flooring due to weight loads.
http://www.johnbridge.com/vbulletin/deflecto.pl

http://www.awc.org/calculators/span...d=10&submit=Calculate+Maximum+Horizontal+Span
I found these sites interesting but hard to pin down for a general rule of thumb. Too many variables involved; Type of wood, condition of wood, dimensional lumber or engineered truss, age of wood and on and on.
http://www.eng-tips.com/viewthread.cfm?qid=62845&page=10
 

jstavis

Candiru
MFK Member
Mar 18, 2009
222
1
48
Madison, WI
Thanks. The first one that you linked (which I've read many times) does mention concrete, but it's incredibly vague. If anyone else has any general information, I'd appreciate it.

Thanks again for the links.
 

skjl47

Goliath Tigerfish
MFK Member
May 16, 2011
4,397
3,777
179
Tennessee
Hello; One way to get a clue would be to determine how thick the floor actually is. If you can find a hole or some other penetration of the floor the thickness can possibly be determined???
 
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