perforated gable end shear wall baloon framed

[eng003]

I have a small gable end with a large opening in the middle. The wall will be balloon framed for a conventionally framed vaulted ceiling with collar ties in middle (no ridge beam or ceiling joists planned) assume rafters will take bending to prevent deflection of wall and colar ties will tie..any thoughts on this? also full height shearwalls left don't meet aspect ratio and perforated shearwall anlaysis in my understanding not permitted for sloping top plate...I guess I am left with designing for force transfer around opening...any thoughts suggestions?

 

[shobroco]

Size of the structure & loads involved would help; how about a sketch? Something small could easily be dealt with by decent sheathing & nailing, but a railcar shed...

 

[RFreund]

I'd be interested to hear opinions on this. I've attached a presentation on the force transfer around opening (FTOA) method which may be helpful. There are also aspect ratios for the FTOA however they are basically the height of the opening.
A few thoughts:

1.) Yes the tie will introduce bending and axial force into the rafters. I'm not a fan of this situation but it is done frequently. Make sure you detail the connection as well. The reason I'm not a huge fan is due to creep deflection over time. Oh thats another thing check the deflection.

2.) Depending on the loads you might try to use the FTOA but you may also want too design the diaphragm and 3 other walls (assuming a box) as a 3-sided box (shear and torsion). Sort of a belt and suspenders technique. Once again it depends on the geometry and loads.



EIT
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