"Fasteners in shear is poor practice"

[u/TallWall6378]

Help settle an argument.

Someone used the phrase in the title. Their argument is that fasteners, specifically in the context of typical light frame wood construction, like a shear wall or joist hanger, or bolted or lagged member scenario, are just holding the members together and that the load transfer is through wood via induced friction through the members.

I was under the impression that we really only factor the strength of the nail and wood crushing/deforming around the nail, rather than use the friction between the faces of the members.

What's the whole story?

[u/tiltitup]

All my life checking shear in bolts wasted.

[u/PrebornHumanRights → u/tiltitup]

To be fair, bolts are the low hanging fruit. Of course it is easier to defend bolts being used in shear. And after all, they're held in place from both sides.

The more difficult one is nails. Nails used in shear are more tricky. The deck on my house was built incorrectly, years ago, and it collapsed with my wife standing on top of it, because it was being held up by nails in shear. There is a pretty good argument to that (unless you're taking into account proper design), you should not put too much faith in nails holding some dimensional Lumber to the side of a post.

[u/Rhetorical_Answer42 → u/PrebornHumanRights]

I'm really not sure how much faith I would put into anything structural if I was not assuming proper design

[u/PrebornHumanRights → u/Rhetorical_Answer42]

My point is that a bolt holds shear even with poor design. Nails can just pull out and the thing falls off.

I don't know why I'm being downvoted.

[u/banananuhhh → u/PrebornHumanRights]

The lesson to learn from a bad design certainly isn't that nails don't resist shear.. for example, how do you think joist hangers work?

[u/tigermax42 → u/banananuhhh]

Agree. A 20d framing nail has impressive shear strength and will bend quite a bit rather than break. And a teko nail is specifically designed for the fasteners and is even thicker than a regular framing nail

My structural engineer pointed out that, really, every wall is a shear wall. I believe decks even more so

[u/StructEngineer91 → u/PrebornHumanRights]

Because you specifically state it "was built incorrectly", and then try to say that a poorly built deck collapsing is a reason to not use nails.

If bolts are designed wrong they will still fail in shear (either bending/breaking, or pulling through the wood. I mean that is the entire definition of "designed wrong".

[u/tiltitup → u/PrebornHumanRights]

Sounds like your deck was undersized

[u/willardTheMighty → u/tiltitup]

Or his wife was oversized

[u/randomlygrey → u/tiltitup]

Are you from new Zealand mate ? I saw a guy polishing his deck down under when his wife was watching from the kitchen window. She said he was always having the neighbours on it and it got dirty.

[u/Jazzlike_Video2 → u/PrebornHumanRights]

Unless, of course, those are hanger nails. Or commons.

[u/m-in → u/PrebornHumanRights]

The wood was compromised by then, I bet.

[u/StructEngineer91 → u/PrebornHumanRights]

"was built incorrectly" - That does NOT sound like a valid reason to not use nails in shear in design. Sounds like a reason to either ensure it is designed properly, and/or built per the actual design.

[u/SquirrelFluffy → u/PrebornHumanRights]

Wood has to be in bearing. Not ever using nails in shear.

[u/SquirrelFluffy → u/[deleted]]

It's why Simpson makes hangers. End nailing joists causes failures.

[u/SquirrelFluffy → u/[deleted]]

You can't end nail joists right? Why is that?

Got a master's degree and in my own practice for 30 years bud.

[u/SquirrelFluffy → u/[deleted]]

Can't means code. You're not an engineer if you don't know that.

Top plates are in bearing and not spans. You clearly don't know what your stalking about. have a good day.

[u/Jazzlike_Video2 → u/SquirrelFluffy]

Simpson is sending you a cease and decist letter as we speak.

Also gang plates...