Full Height Threaded Rods used for Shear Wall Hold-down
Full Height Threaded Rods used for Shear Wall Hold-down
(OP)
What are your thoughts on using full height threaded rods for plywood shearwalls. Full height threaded rods have been the industry standard in my area for years however engineers and contractors do not use skrinkage compensators. I have read that if shrinkage occurs and there is a 1/4" gap between the top plate and threaded rod washer, the shearwall loses 70% capacity.
I'm just wondering if anybody could justify using full height threaded rods without skrinkage devices?
I'm just wondering if anybody could justify using full height threaded rods without skrinkage devices?






RE: Full Height Threaded Rods used for Shear Wall Hold-down
AT75 Auto take-up devices by Commings Manuf. Inc., Friday Harbor Wa.
RE: Full Height Threaded Rods used for Shear Wall Hold-down
Mike McCann
MMC Engineering
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RE: Full Height Threaded Rods used for Shear Wall Hold-down
RE: Full Height Threaded Rods used for Shear Wall Hold-down
RE: Full Height Threaded Rods used for Shear Wall Hold-down
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RE: Full Height Threaded Rods used for Shear Wall Hold-down
http://www.comminsmfg.com/
RE: Full Height Threaded Rods used for Shear Wall Hold-down
Do you specify shearwalls without shrinkage compensating devices?
RE: Full Height Threaded Rods used for Shear Wall Hold-down
http://www.holdown.com/
RE: Full Height Threaded Rods used for Shear Wall Hold-down
For a narrow tall wall, the effect of shrinkage will drammatically increase the % of "hold down deformation" that occurs in the wall. That will make it much more flexible. If drift / deflection is a major factor in the final design then you may be in trouble.
The shrinkage term will not have nearly so much of an impact on long, squat walls. That's because the hold down term does not get magnified in the same way on these walls. Or, at least it results in a lower percentage change in the wall stiffness.
Also, my impression was that the deflection take up devices are mostly a seismic / california thing. And, that you would not nearly as likely to see these in other parts of the US.
RE: Full Height Threaded Rods used for Shear Wall Hold-down
1. Tall narrow heavily loaded shear walls in multiple story buildings (high wind or seismic lateral loads).
2. Log homes where you are trying to use friction between the logs as the first failure mechanism for lateral loading and bearing on the rods as the secondary failure mechanism. The devices give you a consistent loading for friction if you find ones that have enough take up to compensate for log shrinkage.
RE: Full Height Threaded Rods used for Shear Wall Hold-down
I tend to agree with you.
I recently found an article written by Ronald F. Nelson in structure magazine where he says that the loose shearwall hold downs may reduce "initial wall stiffness but had no effect on ultimate capacity"
RE: Full Height Threaded Rods used for Shear Wall Hold-down
With log construction I usually use an adjustable tie for 'settling' purposes. The logs shrink radially with drying.
Dik