Adjustment Factors
Adjustment Factors
(OP)
I am designing my first wood structure (a garage) and have a question about the adjustment factors. Currently I am designing a 2x6SPF No 2 stud for an exterior wall. As far as I can see, under to worst loading combination, I have the following adjustment factors.
CD = 1.6 (wind case)
Cf = 1.3
Cr = 1.15
When I multiply these together I get an increase of the allowable bending strength of 2.392x the base design values. This is quite large.... Is this correct for this condition?
Sorry about the simple question.
CD = 1.6 (wind case)
Cf = 1.3
Cr = 1.15
When I multiply these together I get an increase of the allowable bending strength of 2.392x the base design values. This is quite large.... Is this correct for this condition?
Sorry about the simple question.





RE: Adjustment Factors
You also have to check for the D+L condition without the Cd = 1.6 case. You'd use Cd = 1.0.
RE: Adjustment Factors
RE: Adjustment Factors
Example, SYP #2 as my top plates has a value of 90 psi. Can this be increased for a wind only collector and if so how much (1.4, 1.33, 1.6)?
Any opinions or thoughts are appreciated.
Thanks !
RE: Adjustment Factors
RE: Adjustment Factors
Be sure to be cognizant of the additional wall stud bending increase factor in IBC to use in lieu of Cr = 1.15. I believe it is 1.35 for a 2x6 and 1.5 for a 2x4.
I can't recall the exact provision right now, but it is in the wood section of the code. I would check that out to see if it applies to what you are doing.
RE: Adjustment Factors
In the part of the country I come from we don't use the IBC.... We only use a state interpreted version of the IBC... and the adjustment factor only applies to studs spaced ano more than 16" o.c. My studs are spaced at 2'-0" o.c. (forgot to mention that above).
Not being used to wood design, I was just shocked that the number was so high (and it looks like you can go even higher for some cases).
RE: Adjustment Factors