5/8" OSB Roof Diaphragm Allowable Shear

[cmhski]

Based on the gravity loads (Dead = 25 psf, Live = 16 psf, and Snow = 150 psf) and truss spacing = 16" o.c., the roof sheathing has to be 5/8" Str. 1 OSB.

I have determined the shear demand for the roof diaphragm (when determining the seismic shear loading, the snow load can be reduced by a third according to the local codes).
However, the UBC Table 23-II-H only goes to 15/32", so I am kind of struck...

Are there any other resources w/ tables for determining the nailing shedules/blocking for thicker panels?

Thanks,
cmhski

 

[boo1]

Maximum spans and nominal uniform load capacities for roof sheathing materials are given in Table 3.2B. The ASD allowable uniform load capacities to be used for out of plane wind design shall be determined by dividing the nominal uniform load capacities by a safety factor of 1.6. The LRFD factored uniform load capacities to be used for wind design shall be determined by multiplying the nominal uniform load capacities by a resistance factor, ?b, of 0.85. Sheathing used in diaphragm assemblies to resist lateral forces shall be designed in accordance with 4.2.

http://www.awc.org/pdf/2001WindSeismicSupp.pdf

 

[cmhski]

Hi boo1,

Thank you, but that does not answer my question...

I have already determined my required span & gravity load capacity. The seismic shear demand controls, not wind (seismic zone 4 + snow).

Once again, ASD Table 4.2A only goes to 15/32" thickness for Str.1, which does not help me with my 5/8" thickness - looking at the table, it is obvious that the shear capacity increases with thickness, so it would be nice to have a source providing the capacity for thicker panels, instead having to go with the conservative assumption of using the capacities of 15/32" Str. 1, and then having to specify a really close nailing pattern.

cmhski

 

[JAE]

cmhski -

The tables only go so far because that may be the limit of the approved testing. So to take advantage of a thicker panel, you'd have to go through a testing procedure and get ICBO approval of it.

I note that the IBC 2000 has table 2306.3.1 which includes 19/32" panels. But this would not apply if you are under UBC.