Craig, a free-body-diagram of the bolt would shed some light on the problem.

In this case, I would say the bolt is subjected to single shear based on the following:

- it's conservative, justifying double shear would take some in depth analysis

- I am assuming your corrugated metal is thin (likely gauge material)

- the shear plane where the metal is in contact is easy to justify as single shear

- the shear plane on the opposite side has a gap...

is it less than or equal to 1/4"? then you can ignore it and consider it double shear

is it between 1/4" and 3/4"? then you have to reduce the strength and shim it

is it greater than 3/4"? then you have to fasten the shim to transfer the load

- going back to your free body diagram of the bolt...

considering it as a beam, is your load closer to one support than the other?

would you be inducing bending on the bolt? that is best to be avoided

We can conclude that one shear plane is loaded more than the other. But, by how much? Any justification of the amount would be subject to judgment and be questionable by the reviewer. To find the true answer, testing would likely be required.

So yes, it is likely double shear, but in practice you should only consider single shear. You need to be able to justify any model presented in your calculations. Designing for single shear is the safe choice.

From what you are describing this is a different condition than a though-bolt in HSS, which is common and designed as double shear.

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Chad Morrison P.E., M.ASCE

Professional Engineer

Greenville RI

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Original Message:

Sent: 10-16-2019 10:26

From: Craig Smallegan

Subject: Single vs. Double Shear Plane

Got into a discussion around the office yesterday about single vs. double shear on bolts. It's usually quite straight forward, but what if the center piece of the connection is corrugated? On the global scale, it is still in double shear since there are two outer flat plates pulling one direction and an inner corrugated plate pulling the other. So P/2 + P/2 = P. But on a local level looking at an individual bolt, it now has a stack-up of metal, metal, gap, and metal. Does this gap now put it in single shear?

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Craig Smallegan EIT, A.M.ASCE

Design Engineer

DeMotte, IN

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