grouper therapy;1093154 wrote: If the beam alone will support the load then I assume the joist direction is irrelevant. Yes?
Well, since you asked....:shades:
Everything below is assuming the joists and beam are parallel with each other.
Assuming the sketch is "to scale" with the beam being over half as wide as the tank and the beam actually is strong enough, then it may be fine. I am guessing the beam is not as wide as drawn and that much of the load could be carried by an adjacent joist if they are running parallel to each other. If the question must be asked how to situate the tank on the beam, my instinct asks if the beam is actually designed for the load. I only say this because I am a bit (insert word here) about making sure my own house and future 180 tank do not break due to structural failure or deflection in the floor. I also know how to actually calculate the loads, stress, deflections, etc... without relying on span tables or hearsay, so it makes my above referenced condition even more acute
Since I do not even have a large tank....most people would stop reading here and I would not blame them
The 180 gallon tank, stand, sump, water, rock, canopy, etc... will likely be somewhere between 1 to 1.5 tons so it is no small load and standard house floor systems are not designed for this type of loading. A typical factor of safety of 1.2, could place the entire weight for design closer to 2 tons - although that is likely a conservative number.
If <u>any </u>part of the 1 to 2 ton load is between structural members, some portion of the load <u>will </u>be transferred to each adjacent structural member - whether it is a beam or the next joist - there is simply no changing this without some crafty engineering and significant expense... or some unknown scientific discovery that contradicts the basic laws of physics
All subfloors are typically strong enough for the job they are intended for, but they do not place the load entirely on the beam in the cases drawn below. A subfloor transfers the load applied to the adjacent structural members, ie: 2 joists, a joist and a beam, etc. In almost every case reasonably conceived, the subfloor will do the job of transferring the load to the structural member - the exception typically being a point load such as putting the tank on four legs that do not spread the load across the subfloor in any manner, thus resulting in a punching force through the subfloor. I have yet to see a tank stand for anything over a 55 gallon built with the load applied at only 4 points except some commercial systems that are on concrete slabs...of course I still have a lot to see in life, so I may yet see one.
Most large tank stands I have seen place all the load down the sides, back, and front of the strand. This means that the load is not actually distributed across the floor identical to the way the weight is distributed in the tank bottom. Therefore, a little less than half of the tank weight is carried under the back wall of the stand, same for the front, and a little at the ends ... depending on how the stand is built. Some stands I have seen carry all of the load at the ends or have other vertical support walls within the stand. The bottoms in the large tank stands I have looked at do not distribute the load evenly across the subfloor but often times do distribute the sump weight evenly if there is not a raised floor in the stand.
This is really diving deep here but there is a point:huh:
The point is that roughly half the load <u>could </u>be between the beam and the next adjacent structural member - IE a standard joist. If that next structural member is supported by a structural wall (IE most exterior walls), then there is likely no further need for reading and the tank will be fine as long as the beam system is strong enough (and the foundation under the structural wall is strong enough, which I suspect is most likely)....if not, keep reading on.
Basically, the distance the tank overhangs the beam divided by the distance from the beam edge to the next support member times a little less than half the total system weight (assuming it is parallel) will likely be what the next support member carries - depending upon the stand and other factors. If the next adjacent member is a standard joist, it may not be up to the task and may deflect a lot more than the beam.
Whew...that was a lot.
If you have read this far, you now understand my (insert word here) condition mentioned above
I hope you enjoyed it either way and fully expect some will disagree based on their years of experience having large tanks. Experience is worth a lot. I would also expect there have been tanks sitting in conditions similar to the options in the pictures without issue for many years. I also suspect that some of the tank leaks and seam failures we hear about are due to floor systems unable to support the load properly.
That is a lot said....remember that I have a very acute condition
so take the info or leave it, it is up to the reader to decide.
...Just in case anyone is asking, I am not intending to challenge anyone, just tossing out my lengthy two cents in an attempt to explain my point. I am sure there are many points of view on this. Remember that I am relatively new to saltwater and therefore have a relatively new interest in large tanks. I sold a 180 without setting it up since adding the support beams was going to make the setup yet another project to be delayed indefinitely...which I have too many of already
If considering experience with large tanks, my signature below says it all...
alt="" />
alt="" />
