pony wall shear wall (seismic retrofit)

[mikeCTE]

greetings,

i'm working on seismic retrofitting my basement (seattle area). originally, i thought my pony walls would be 48" or less, allowing me to use 4'x8' sheets of plywood horizontally. however, after opening up the walls, i now find that i'm at 52".

my question pertains to orientation of plywood panels. if i orient vertically, i would add a vertical stud as required for edge nailing. if i orient horizontally, where would the ideal location for the horizontal blocking be located? 1/2 of the height? at the very top? etc? or, would it be better for me to just add 6" of blocking in the stud bays at top and bot plates so i could use a 48" wide sheet?

also, to confirm my methodology: i am adding holddowns at every discontinuity in my walls. so, for example, at a window, i will add a holddown near the window and then at the opposite end of the continuous pony wall (plus shear anchors too). then, after plywooding, i will add some CS16 straps around the windows to tie everything together.

thanks

 

[msquared48]

Yup.

Mike McCann, PE, SE (WA)

 

[mikeCTE]

one of my best friends worked for Rob back in 2005-2006 as an intern.

i did reach out to dibble for some advice on the retrofit, but that fell through. oh well. i'm most of the way there!

 

[msquared48]

Have a good and safe weekend...

I know, what's fun about that?

Mike McCann, PE, SE (WA)

 

[mikeCTE]

i'm dredging up this thread for one more question regarding strapping.

i'm now done with the retrofit of my basement, and am moving onto the garage where there is a bad softstory due to double 9x7 garage door openings and very narrow walls on either side of the door openings. from my basement, i have one key shear wall that i designed to handle the bulk of the shear load for the front half of the house (struct 1 plywood (eventually adding to the exterior side as well), 2" OC nailing, tons of blocking, and a simpson CMST12 strap rated for 9200lbs). the simpson strap currently daylights through the partition wall in my garage (the one dividing the basement and garage areas). i've left enough length to fully develop the strap.

my question pertains to adding plywood to the framing above the garage doors. right now, the walls are drywalled, but i'm fairly certain all the framing above the garage doors will be solid wood (likely a 4x10 or 4x12 header with 4x6 jack studs). it would be much easier for me to simply run the strapping without the need to install plywood over the studs since the attachment for the garage door rails are lagged to the studs. i did the the install on the garage doors, so it's not like i couldn't do it again, but i would prefer to avoid it.

so, is it okay to skip the plywood?

any other considerations i should have for the garage door openings? i'm planning to install hold down anchors - 2 each per side wall - at both of the walls on either side of the garage doors.

thanks