WFCM SHEARWALL TABLES FOR WIND LOAD

[PT999]

Residential Construction
I am looking at Wood Frame Construction Manual (WFCM-2001ed) segmented shearwall endwall sheathing requirements (Table 3.17A)
Suppose for my situtation, 20 ft min length is required. Do I comply if I have multiple shearwalls say 5 or 10 ft each along an endwall that add up to 20 ft, or does it mean one continuous 20 ft section is required.

Looking at Holddown Capacities (Table 3.17F), how does the specified capacity relate to length of shearwalls?

 

[samdamon]

See Sect 3.4.4.2.3 about holdowns, you can divide up the total required length of shear wall required into segments but ea has to be within the aspect ratio limits of Fig 1.7

 

[PT999]

OK, minimum lengths dependent on aspect ratio of 3.5.

Table 3.17F shows required hold down force without considering lengths of segments. Are the forces proportional to total length required, or does each segment get holddowns for the force shown in the table.

 

[samdamon]

Pt999- In prescriptive design the hold down allowables are based only on the height of the shear wall, not the length of the segments. Thats counterintuitive but its meant to keep prescriptive design simple. You will need to place hold downs at each end of each shear wall segment, or, depending on how many openings you have in the wall, it may be possible to treat the wall as "perforated" in which case the number of required hold downs can be reduced. Table 317E gives factors for modifying the total length of shear wall required if using the "perforated" design concept. Perforated shear walls only need hold downs at each extreme end.