Force transfer around openings CBC 1

[BRL43]

First, does anyone have an example of the "rational analysis" needed for force transfer around wood shear wall openings. This was talked about in a previous thread but I didn't really see a resolution (and this was IBC):

http://www.eng-tips.com/viewthread.cfm?qid=158780&page=4

It seems like a "tic-tac-toe" method of designing each panel is necessay. Given a wood shear wall with one window opening (like Figure 12-II-1, 2001 CBC) does the wall pier recieve the shear drag across the top of the window opening? Is that force then used to design the horizontal and vertical straps along the window perimiter? If the force transfers through the strap to the bottom sill of the window, it seems like the shear panel below the window has shear capacity.

Second, is there a way to add the shear capacity of the moment resisting action of the "APA Narrow Wall Bracing" technique of 8d nails in a 3" O.C. grid pattern into a header at the top corner of a shear wall?

Thanks, Ben San Diego

 

[jatwood]

See SEAOC Seismic Design Manual II or Wood Engineering and Construction for examples. Basic idea is to assume inflection points at mid points of piers and spandrels and tackle the statics accordingly. Good luck

Jason

 

[LGARG]

Hi, I agree with jatwood. you have to assume inflection points at mid points of piers and spandrels and you have to check that each one of the panels comply with minimum ratios given in the UBC.If you have small heights between top plates and headers above windows the unit shear at each panel it´s two times bigger than the unit shear at the shearwall

 

[csd72]

Check out

http://www.awc.org

they have some good articles on perforated shear walls.

LGROSSI - "..it´s two times bigger.." Does that mean it is three times as big? (i.e 2 times =200% => 200% bigger!). Sorry but this is a bad use of english that seems to be more common these days, be careful using that in reports as I am sure I am not the only one that will note the ambiguity.

 

[LGARG]

Csd72 you´re right my english is not so good.my native language is Spanish. What i mean is that shear is two times the shear value depending on the heights between the top plate and the header. Thanks for your suggestion it´s always welcome.