Effective Wind Area - ASCE05

[cgstrucg]

Hello,

I am working on the design of a roof beam system which has a lot of beams @ around 6 ft spacing and span length is 30 ft. While computing beam uplift, I have to consider the effective area for members. Traditionally effective area is span length multiplied by trib width which in this case is 6ft x 30ft. But for roof component and cladding load is higher and as far as I understand from ASCE, I have to take effective area as span length multiplied by span length/3 that is 10ft x 10ft/3.

My question is - I got my uplift value say 30 psf using span length/3. When I am putting these uplift values in STAAD, do I use 30psf * span length * span length/3 or 30psf * span length * actual trib width. I am sorry if it is confusing so just giving it another try -

1. Used span length/3 to get Uplift Value
2. Shall I use span length/3 when converting 30 psf to plf like 30 psf*span length/3(3.333ft) or shall I use actual trib load like 30psf*6ft.

Thanks

 

[dold]

Effective wind area need not be taken LESS THAN span*span/3.

 

[moments]

The magnitude of pressure uses the effective wind area, but a manual calculation of line loading based on that pressure would use the width tributary to that member.

 

[cgstrucg]

Thank You. Thats what I thought. It was a bit confusing so wanted to confirm here.