IBC Allowable Shear in Shear Wall Tables

[pepe1234]

Question regarding how to interpret Tables 2306.4.5 (Allowable Shear in Shear Walls) in IBC ’06:

Are allowable shears given in the table assuming only one side of the wall is sheathed?

For example – let’s say you have shear wall sheathed with 5/8” gyp board (single ply), blocked, fastened 7” maximum. Table gives a value of 145 plf. If we have a shear wall that is that sheathed on both sides with 5/8" gyp board, is the allowable shear 290 plf?

Thanks!

 

[IceNine]

Not sure about '06, but Section 2305.3.8 in IBC 2003 states that the shear values are cumulative.

 

[csd72]

pepe,

not necessarily - the required tie downs and the adequacy of the studs may come into play.

 

[KBVT]

In terms of the unit shear capacity, yes, the tables in IBC assume that it is sheathed on a single side. Make sure you remember that the gypsum capacity values can not be increased by the 40% that the plywood/OSB tables allow for wind controlled design.

Like csd72 mentioned, you still need to design for the anchorage and the diaphragm unit shear as well to ensure that you can utilize the full shear capacity of the weall sheathing.

 

[msquared48]

The shear values are cumulative, but I would use the same materials and nailing on each side of the wall.

Ane for walls with three sides, you can triple the values!! (just kidding).

Mike McCann
MMC Engineering

 

[akastud]

I like your thinking Mike,

But the third and fourth sides of a 2x6 wall usually don't meet the height to width ratio, (unless you are still working on that dog house).

akastud