Bolt Bearing Check at Threads 3

[Althalus]

I'm looking at AISC J3.10, Eq J3-6 (a,b) for bearing strength. Is there a reason no mention of threads is included in this analysis?

It would seem to me that if the bearing occurs at bolt threads, it would have a tendency to have more deformation in the member steel. Or does this equation automatically assume that threads will be included in the bearing?

 

[dik]

If I'm understanding the question, these are 2 different issues (by Canadian Code) anyway. The fastener strength is reduced for threads included, and there is a bearing capacity. They are separate calculations.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[271828]

I think that's sharpening the pencil too much.

Bearing "failure" is excessive deformation of the steel. Think majorly reaming out the side of the hole. Whether the threads bite into the material a little more isn't a major consideration.

 

[dik]

My SMath program checks bolt size, material, threads included/excluded, bearing, slip critical/snug tight.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1641830561/tips/Bolt-Design_s98pe4.pdf[/url]

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1641830561/tips/Bolt-Design_vl7vvs.sm[/url]

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

Because I cut and paste my programs, variables needed for SMath (included in the SMath file) are: Fu2 = 70 Ksi, and thickness of material w = 0.5"... doesn't show up in the *.pdf file.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[bones206]

According to the commentary for this section of the spec:

Bearing strength values are provided as a measure of the strength of the material upon which a bolt bears, not as a protection to the fastener, which needs no such protection. Accordingly, the same bearing value applies to all joints assembled by bolts, regardless of fastener shear strength or the presence or absence of threads in the bearing area.

 

[Althalus]

Quote (AISC 360-16 Commentary J3.10) ... or the presence or absence of threads in the bearing area.

Awesome. That's perfect.

Thanks.

 

[bones206]

No problem. Commentary authors are the unsung heroes of our profession