Shear Transfer at Stud Walls
Shear Transfer at Stud Walls
(OP)
I have a 50'x 200' gabled building where the roof purlins are running parallel to the perimeter shear wall below in the 200' direction. The purlins span between glulam beams spaced at roughly 20' o.c.. The contractor wants to place the purlins on top of the glulam beam in which case transferring the diaphragm loads into the shear wall becomes a problem because of the gap. See attachment as this will hopefully help clarify my problem.
I am wondering if I need to treat the end purlin as a drag strut and then transfer my force at the glulam beam support locations or if there is another way to transfer the diaphragm loads.
Thank you for any help.
I am wondering if I need to treat the end purlin as a drag strut and then transfer my force at the glulam beam support locations or if there is another way to transfer the diaphragm loads.
Thank you for any help.






RE: Shear Transfer at Stud Walls
RE: Shear Transfer at Stud Walls
The easiest way to transfer the roof diaphragm shear down the wall sheathing is via a common blocking along the wall length into which both roof and wall sheathing can be connected.
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RE: Shear Transfer at Stud Walls
RE: Shear Transfer at Stud Walls
Mike McCann, PE, SE (WA)
RE: Shear Transfer at Stud Walls
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RE: Shear Transfer at Stud Walls
I would be extending my wall continuously up to the underside of sheathing if it's the latter as opposed to JAE's stubby wall.
Or as msquared mentioned, just have them cut a sloped piece to tack onto the last purlin that allows for the wall sheathing to be fastened to it.
RE: Shear Transfer at Stud Walls
Good detail, but I would also add transverse full depth blocking between the rafters @ 4' OC to support the short pony wall and control the knuckle joint created by not extending the stud wall to the roof sheathing.
Mike McCann, PE, SE (WA)
RE: Shear Transfer at Stud Walls
RE: Shear Transfer at Stud Walls
Why build a pony wall when you could just run the studs up full height? The rest would work out fine. See attached, I just did a project like this a few weeks ago.
RE: Shear Transfer at Stud Walls
The OP says the plate needs to be where it is.
Mike McCann, PE, SE (WA)
RE: Shear Transfer at Stud Walls
Wondering what people think of treating the last purlin as a drag strut and transferring the load at the glulam support location where the double top plate frames into the side of the glulam (see attached). I would have some weak axis bending in the beam but could detail it to handle the load.
Thoughts?
RE: Shear Transfer at Stud Walls
RE: Shear Transfer at Stud Walls
EIT
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RE: Shear Transfer at Stud Walls
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.