huangyhg

nds wood diaphragm table 4.2--what if inclined roof?
in the nds 2005 wood diaphragm tables 4.2a, b, and c, values are given for different nailing patterns, sheathing thickness, grade, etc...but what if my roof is a 30 degree gable? does anyone know where i can read about how inclines affect unit shear resistance values, etc., for a sloped roof diaphragm?
thanks.
find a job or post a job opening
also is there a max slope to where i can no longer assume diaphragm action?
i went to 2005 nds and chapter 4 is for sawn lumber. i am not sure what tables you are talking about.
sorry, i meant table 4.2 a,b and c of the wind and seismic special design provisions, 2005. the thin green/gray book.
it just seems that a wood paneled diaphragm wouldn't work that well in diaphragm action if it's too steep.
thanks
i think you would have to resolve the force into normal and parallel to the plane of the diaphragm.
it shouldn't matter about the slope of the diaphragm. the values are based on unit shears.
i would agree with cjschwartz about resolving it into components when calcing the shearwall loads. i would add this, however: add in the downward vertical force (from the diaphragm) for designing the compression chord, add in the upward vertical force (from the diaphragm) for designing the tension chord and the hold downs.
thanks...so i would take wind (or equake) * cos 30 for my in-plane sheathing shear check/bdry element check, and wind (or equake) * sin 30 to check flexure of the sheathing out-of-plane...
are you asking about a bent-plate diaphragm?
bent plate? i am talking about 7/16" osb wood panels nailed to the top chord of gabled pre-engineered trusses...sloped wood diaphragm...thanks
keep in mind that when you resolve your horizontal shear to an inclined in-plane shear, the shear value will go up (the sloped diaphragm is less efficient resisting the horizontal shear at its inclined angle)
....but the diaphragm also should be checked using its sloped length (which is also longer) to get the shear per foot of diaphragm.
jae,
it seems to me that if the horizontal shear is the resultant shear, resolving into normal and parallel to the plane shears would result in respectively smaller values of shear. what am i missing here?

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