Live Load for "Puppy Play" & Storage 1

[T_Bat]

Odd question here - I've been asked to provide the maximum live load an existing mezzanine inside of a PEMB can support using the 2012 IBC. The mezzanine is actually an interior build out that creates some offices and meeting spaces. The mezzanine is the area above these spaces. The walls are all wood 2x4 and the mezzanine framing is what appears to be 1000s162-54 CFS joists. Based on the existing bearing wall locations and assuming a simple span I get that these are good for about 60 psf of live load.

So here is the tricky part - this building is being used as a dog training facility and they want to use the mezzanine as some light storage and part of the mezzanine will have what they are calling a "puppy play" area. Basically, a room where they will have some training classes for puppies. What live is this? Safe to assume just classroom loading (40 psf) for the puppy play area and storage area above ceilings for the storage (20 psf)? I know the commentary for ASCE 7-10 has a live load for a nonresidential attic (see table C4-1) but I'm not sure what the differentiating factor would be.

Thoughts?

 

[T_Bat]

Maybe habitable attic with storage for the storage area?

 

[CANPRO]

If it’s good for 60psf, I’d just tell the owner that it’s good for 60psf or approximately ‘x’ number of people (and/or dogs)

 

[T_Bat]

Interesting thought. Do you know what a typical person/psf is? I mean we could assume a 200 lb person takes up a 2'x 2' space? That's basically 50 psf. Even that's proably pretty tight for what is a reasonably dense group of people.

 

[TehMightyEngineer]

There's a great little graphic in AASHTO pedestrian bridges that shows how PSF live load really depends on spacing of people more than anything else.

Ian Riley, PE, SE
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[T_Bat]

That's a great picture. I feel pretty god then about the pups being less than 60 psf

It's interesting to see what these live loads correlate to...

 

[CANPRO]

Putting an actual limit to the number of people is a bit of a judgement call. The picture above definitely helps put things in perspective.

If you provide a maximum number of people, just keep in mind that there might be other limits that trump your structural limit - like occupancy based on the fire code. In the past, I've worded these ratings something like "60psf or approximately "x" number of people evenly distributed, or as limited by the building occupancy"

 

[dhengr]

T_Bat:
Puppy play loading and light storage loadings can vary wildly, all in the eye of beholder. “What appears to be 1000s162-54 CFS joists”, at what mat’l. strength, doesn’t sound very certain to me. Will the actual connections and construction details really carry that max. member cap’y? You should check these things out to determine which is the controlling condition, and to cover your own butt. You don’t have much control over the situation until something goes wrong and you are blamed, and that’s too late. So, protect yourself by having a complete study and set of notes and calcs. on the existing conditions. If your calcs., etc., indicate 60lbs./sq.ft., then report that, not how many people can be up there. Because, while you think 175lb./person, and they will assume 300lb. puppy lovers jumpin around up there. W.r.t. storage, at least take a look at a few full three drawer file cabinets, in the worst possible locations on only a couple joists, to see if that’s a problem you should comment on.

 

[T_Bat]

dhengr - thanks for the info. I assume the joist size based on my field measurements. All of the joists bear on 2x4 wood studs walls and the bearing length (crippling) is what controlled the max load. I gave the owner a max live load and said it was good for classroom (40 psf) and storage above ceiling loads (20 psf) which are the uses they wanted me to verify. I assumed 50 ksi material since I have always been under the impression the 54 mil and up is always 50 ksi material. Good call on the filing cabinets...

 

[BridgeSmith]

"All of the joists bear on 2x4 wood studs walls and the bearing length (crippling) is what controlled the max load."

Forgive my unfamiliarity with the terminology, but are you saying that buckling of the 2x4s in the wall governs the capacity of the system? If so, would it not be a fairly simple matter to use sheathing (OSB) on those walls that would provide bracing and added axial capacity?

 

[T_Bat]

No sorry HotRod - I mean that the CFS joist webs crippling controls the design.

 

[BridgeSmith]

Ah, that makes more sense, T Bat.