Fitness floor LL 1

[cmbyrd77]

I have a client who wants to convert a building into a gym. There is a second floor that he wants to put circuit traing equipment on. The IBC has never really done a good job of giving live loads for rec/fitness floors. Does anyone have an idea of a safe LL to use in my design. I'm wondering if 150 psf is not enough or too much. I'm treating the equipment as a LL since it may be shifted around. Any help is greatly appreciated.

 

[frv]

I would think 150 psf is plenty. Be sure you check vibration, which can certainly be an issue in change of occupancy.

 

[Michel60]

Good evening cmbyrd,

Gyms and health clubs have a lot of open space with really intense localized loads. 150 psf sounds generous overall but you may want to look at what could be happening at individual members in more detail. I'd be asking the client for cut-sheets on some of the likely equipment to see what sort of loading intensities are possible.

regards,
Michel

 

[IsaacStructural]

I agree the equipment should certainly be considered a live load.

150psf seems heavy to me. As Michel points out, health clubs typically have large open areas combined with localized areas of heavy weight (racks of free weights are probably your biggest culprit). Treadmills aren't that heavy, a few hundred pounds, but spread over around 15 square feet. I'd see if 125psf or 100psf would satisfy. Perhaps you can do an analysis using some actual point loads from machines/loads placed in worst case scenario arrangements and compare that to an equivalent distributed load. It might help give a sense of scale and see if your 150psf is really needed.

Do consider running a floor vibration analysis. Serviceability might dictate your design more than strength in this case.

M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)

 

[racookpe1978]

But consider a "exercise floor" in a dance or aerobics room on those floors: Could be 90 lbs per person spread out with 5 or 6 feet between people. Might be a 200 lb person lifting a 90 pound guy while standing on her toes: 290 lbs on a 2 inch x 2 inch surface area holds all the load. 8<)

A single machine (treadmill for example) is going to put all of its load on four very small points at the legs. Its not a "uniform" load spread out over the whole floor area of the machine.

 

[cmbyrd77]

Thanks for the information. I see where a few of you mentioned checking for vibration. I don't think I've ever even fathomed doing this for wood members. Any advice, or literature. I don't the NDS covers this at all. I know there will be no aerobics rooms up there or treadmills. It will be all circuit training machines, which usually max out at about 150-200 lbs worth of lifting weight and then the machine itself.

 

[flight7]

IBC calls for 100 psf for gymnasiums. That sounds like a good overall average to me. You might want to use 150 or 200 psf for your secondary members. Sort of a variation on the concept of reducible live load. As others have said, check vibration as well.

 

[ztengguy]

Also think of the guy leg pressing 700lbs, the machine, and his large body all in a few square feet, or at least a few point loads from the machine. just a thought.

 

[WARose]

I see where a few of you mentioned checking for vibration. I don't think I've ever even fathomed doing this for wood members. Any advice, or literature. I don't the NDS covers this at all. I know there will be no aerobics rooms up there or treadmills. It will be all circuit training machines, which usually max out at about 150-200 lbs worth of lifting weight and then the machine itself.

I’d still check it out. Circuit training machines (and circuit training in general) can still cause noticeable excitations. And I would note on the drawings that what you designed for and what you expect to NEVER be on that floor. I say that because I had an elevated floor like that once (in a gym)…..I designed it based on what the owner told me: there will never be an aerobics class up there. Well guess what? I joined that gym about 5 years later…..and it was like a disco club up there.

In any case, the best source I’ve seen to check floors for this kind of vibration (by human footfalls) is: “ATC design guide 1 : minimizing floor vibration”.

 

[Shaniak]

Here are a couple of articles on wood floor vibration (care of Dr. Frank Woeste who spoke on this topic at the SEA of OH conference this month):
Structural Engineer Magazine Article
JLC Magazine Article

Also, I recommend you consider fatigue in the connections between wood members. Due to the repetitive loading this floor is likely to experience, you may want to oversize any hangers or fasteners.

-Shane

 

[IsaacStructural]

racookpe1978 ,

While I agree with your point that the load of a treadmill will only be applied via a finite number of feet on a given machine, the fact is, the machine still occupies floor space, so you won't have those 15 or so square feet occupied by other loads. The load from the machine's feet only pose a risk if you are concerned about a punching failure. As others have point out, if you are concerned with this, you should also be concerned with heavy lifters doing squats, who may place 500lbs spread over the area of the ball of their foot.

No load is ever truly uniform. look around your office, desks, chairs, bookshelves, these all apply point loads to the floor, but we don't design for each piece. Watch out for especially heavy equipment, but you don't have to go bananas tracking the location of every little bench and water cooler.

Shaniak raises a good point, I did not realize you were designing this floor with wood framing in mind. I agree with him, connection design and fatigue may be an issue and deserve your attention.

M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)

 

[BAretired]

This is not a new design. According to the first post, it is a conversion of an existing second floor into a gym. It is not going to be easy to check the existing structure unless the ceiling below can be removed for inspection purposes and to provide access for remedial work.

Concentrated loads will likely be an issue. If the existing deck is plywood or particle board, you may want to apply an additional deck on top.

BA