Combination of Roof and Floor Live Loads

[80smoviefan]

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.

 

[MacGruber22]

ASCE 7/IBC code?

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

 

[medeek]

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

http://www.medeek.com

 

[BAretired]

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

 

[80smoviefan]

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

 

[hokie66]

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.

 

[msquared48]

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)

 

[hokie66]

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

 

[msquared48]

Ok.

Mike McCann, PE, SE (WA)