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Combination of Roof and Floor Live Loads

Combination of Roof and Floor Live Loads

Combination of Roof and Floor Live Loads

(OP)
Hi all,

Say I have a floor beam that is supporting two different roofs as well the floor. When I come to load combinations, is Q (live load) simply the two roof live loads combined with the floor live load or is that not right?

Thanks in advance.

RE: Combination of Roof and Floor Live Loads

ASCE 7/IBC code?

"It is imperative Cunth doesn't get his hands on those codes."

RE: Combination of Roof and Floor Live Loads

ASD or LRFD?

Check your load combinations: 2,3 and 4 (ASD).

Also if your roof and floor tributary areas are quite large check for live load reductions for both roof and floor loads.

A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com

RE: Combination of Roof and Floor Live Loads

Live load reduction factors based on supported area cannot be applied to snow load. Otherwise, the beam live load is snow load plus floor live load.

BA

RE: Combination of Roof and Floor Live Loads

(OP)
Hi,

I am using AS/NZ 1170. Which is the Australian/NZ code. This is for limit state design.

Load combinations for ULS (ultimate limit state) are:

1.2G + 1.5Q
1.2G + Su + zero x Q

G + 0.7Q
G+ 0.5Su

RE: Combination of Roof and Floor Live Loads

Yes, you add them all up. As to LL reductions, you can reduce the floors, but the code doesn't allow LL reduction for roof load. The roof LL is already too skinny, as evidenced by what happens in hailstorms.

RE: Combination of Roof and Floor Live Loads

You can reduce roof live loads of 100 psf or less if it would be appropriate for the load type, but not roof snow loads.

Mike McCann, PE, SE (WA)


RE: Combination of Roof and Floor Live Loads

Mike,
He is asking about the Australian code, which does not permit live load reduction for a roof.

RE: Combination of Roof and Floor Live Loads

Ok.

Mike McCann, PE, SE (WA)


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