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WARNING against using Staples in shear walls/diaphragms

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My first impression of stapling plywood is that it may be a better system than nails. Design factors may need to be re-considered. My strongest concern is corrosion of the staple, not its resilience in a seismic event. A water repair should include a review of the staples.

Following are what I intend to find answers for and these are followed by some facts that can help.

What spans are the drift values for?
When is the drift limited by the gaps between the panels edges?

If drift exceeds 1", how probable is it to not witness a permanent deflection? Is a nailed diaphragm allowed to remain if there is evidence of a 1" drift?

Over the shorter distance of the staple drift could the staple demonstrate a higher resistance than the nail and absorb more energy? Could more staples develop this equivalent energy absorption?

What are the COLA/SEAOSC and CUREE test methods as they relate to the above questions.

I have talked to a contractor who I had remove a stapled diaphragm. The stapled plywood, was twice as difficult to remove than a similar nailed system. That suggests that when panel edges bind it might be more likely for a nailed panel to separate, out of plane, from the framing.

Like gypsum, there might need to be more staples. Gypsum, with the proper design penalties and correctly installed, can out perform the equal plywood option.

Lately I have heard of testing of shear walls, at SJSU. Inadvertently, they discovered the shear wall nails were not yielding before the hold-downs failed. That probably results in little energy absorption. Could it be that we cannot rely on the code design benefits of nail yielding when brittle hold-downs trump the energy absorbing capacity?

David B Merrick, SE

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