Gyp Shear wall capacity

[cg3375]

I was looking for general thoughts on shear wall capacity.

IBC 2306.4.1 allows a 1.4 increase to table 2306.4.1 for wind design for wood structural panels.

I don't see a similar increase allowed for gyp from section 2306.4.5. Is there one? I also don't see a reduction for specific gravity of species framed into. None required like WSP?

Thanks.

Also, if anyone has any insight into the basis behind the 1.4 increase I would love to know. The 2306.4.1 table is for seismic and wind, and then calls later for a 1.4 increase for wind. I was trying to calc back for duration factors of 1.33 for seismic and 1.6 for wind but wasn't getting anywhere.

 

[cg3375]

Along these same lines, does anyone know where the basis for note "l" on table 2306.4.1 comes from for the reduction factors of .63 and .56 for normal or permanent load durations?

Thanks

 

[DaveAtkins]

Ed Keith of APA told me that whenever you see an increase allowed for wind load design of diaphragms or shear walls, it is because a lower factor of safety is allowed for wind load design, compared to seismic design.

DaveAtkins

 

[cg3375]

Do you think we are dealing more with safety factors as opposed to duration factors then?

 

[KBVT]

The reductions of 0.63 & 0.56 are in relation to the duration factors of permanent (0.9) and live (1.0) loadings. The tables are based on seismic loading which has a load duration factor of 1.6.

For permanent, 0.9/1.6 = 0.5625
For live load, 1.0/1.6 = 0.625