Perforated shear wall design

[drewtheengineer]

When performing a perforated shear wall calculation, a factor (F) is determined. Now if I have more than one wall in line with each other is it proper to multiply this factor times the length of the perforated wall (giving me an effective length of just one of the multiple walls), then adding all the effective lengths together. From there, I would get a plf to size my shearwall. In this case, all of my shearwalls that are inline will be the same design (they all share the same plf).

or...

Should I first come up with a plf based on the lengths of the walls then divide the perforated walls by the appropriate factor (F). In this case, the shearwalls that are inline may be different designs (they have different plf).

I guess with the second method, I am decreasing the allowable capacity of the perforated shearwall which makes more sense to me.

 

[FSS]

With perforated walls, you multiply factor times the length of your wall segments. If you have a 15' wall with a 3' window in the middle, you will end up with two 6' wall segments. After determining factor, you then multiply each of the 6' walls times the factor to come up with effective length. You then use this number to get plf value. So yes, all sections along the same "perforated" wall will have same design plf.

 

[drewtheengineer]

I'm referring to multiple walls in line, sharing load, not just one perforated shearwall.

After I wrote the first post, I saw that there is another method (actually it's the method most referred to) where you come up with a Co factor (slightly different then the "F" factor I referenced in my first post.
(F*Ltotal=Co*Lsegments)

Allow me to give an example of the differences.

We have three walls all 8' high.
Wall #1: 10' long with no openings
Wall #2: 10' long with a 4' high x 2' wide window
Wall #3: 10' long with a 6'-8" high x 7' wide window

Wall #1: F=1 and Co=1
Wall #2: F=.727 and Co=.91
Wall #3: F=.146 and Co=.49

Load into wall=1000#

Wall Capacities: G1=100plf G2=200plf G3=300plf (just an example)

Method #1
(using F and applying Length Total)
Leff.=10*1+10*.727+10*.146=18.73'
(using Co and applying to Length Segments)
Leff.=10*1+8*.91+3*.49=18.75'

q'=1000#/18.75'=53.3plf

All walls can be G1

Method #2
(using F and applying to strength capacity of wall)
Leff=10+10+10=30'
q=1000#/30'=33.3plf

Wall #1 use G1 (100plf*1)>33.3plf
Wall #2 use G1 (100plf*.727)>33.3plf
Wall #3 use G3 (300plf*.146)>33.3plf

Method #3
(using Co and applying to strength capacity of wall)
Leff=10+8+3=21'
q=1000#/21'=47.6plf

In this example it works out that all walls can be G1 (100plf*.49>47.6plf) but let's say if Co was just a little smaller, we would have to use a G2 wall. In method #1, this could have remained a G1 wall.

Which method is most accurate (I'm now leaning to Method #3 for the same reason as before. The Co or F factor is based on strength capacity of the wall.)

If any of you have read this far your either really into perforated shear walls or you have a lot of time on your hands. Either way, any reply is much obliged.