Is triple shear of bolt possible?

[myturns]

Bolts subject to shear are designed for both single and double shear. Double shear stress is half of single shear stress in case of same bolt. If double shear is better than single, why don't we use there triple shear, or quadruple shear, etc.? could you explain why triple share is not possible or effective?

 

[hokie66]

Single shear occurs when a bolt goes through two plies, double shear when the bolt goes through three plies, and triple shear when the bolt goes through four plies. I'll leave the rest for you.

 

[JStephen]

It's been done.

http://upload.wikimedia.org/wikipedia/commons/3/3a/Uk_bristol_csbchains.jpg

 

[CELinOttawa]

Higher bolt shear numbers are rare, but they work. It is a function of your geometry.

I like a lot of things about the AISC standard for steel construction, but a detailed commentary would sure be nice. That and a little less recipe-book wouldn't hurt. I think sometimes it fails the user in trying to be so easy to use; a touch too prescriptive for my taste, though I often will read it first when learning something new!

Note that in CSA S16 the shear of bolts is Cl 13.12, and
Vf = 0.6∅b(m)AbFu.bolt
Where n = number of boots
m = number of shear planes

Note that there is no code-imposed limit to the number of shear planes.

 

[CELinOttawa]

Oh, and ∅b is my attempt at 'Phi bolt' and is always 0.8

 

[rb1957]

there's no reason you can't have "n" shear (like a piano hinge).

Quando Omni Flunkus Moritati

 

[myturns]

Thank you for your ansewrs. But according to AISC construction manual table 7-1 Available shear strength of bolts. P.7-22, Why do only single and double shear are difined?

 

[rb1957]

because they are the most common ones, and most relevent for designing stuff.

because you can break your triple shear connection down to double (and single) shear elements.

Quando Omni Flunkus Moritati

 

[CELinOttawa]

Because, unless I've missed something as the AISC is not my normal code, and like I said above the AISC book is very much a recipe-book.

Tripple and beyond are rare. Rare doesn't fit into AISC's simplified approach of "Want X? Do this, in this exact way".

Mind you that makes the AISC VERY user friendly... Just doesn't help you here.

 

[AELLC]

I would think triple shear is 3/2 x double shear, and not 3 x single shear

quadruple shear is 2 x double shear

etc etc

 

[CELinOttawa]

Quote: I would think triple shear is 3/2 x double shear, and not 3 x single shear

3/2 of double shear had better be the same as 3 times single shear, otherwise there is something wrong...

 

[paddingtongreen]

I'm lost.

Three plates yield two interfaces = double shear.
Four plates yield three interfaces = triple shear, this is unbalanced but so is single shear.
Five plates yield four interfaces = quadruple shear.

A rule starts to show, there is/are one less shear plane(s) than the number of plates.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin

 

[AELLC]

No, I was thinking double shear in bolt > 2 x single shear because you don't get so much prying action - I could be wrong, but in wood there is a difference - according to failure mode.

 

[paddingtongreen]

Yes, I was thinking exclusively of steel.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin

 

[CELinOttawa]

Ah, now your comment makes sense AELLC... Yup, wood is a very different story, what with the multiple bolt failure mechanisms, etc.

 

[rb1957]

in thin metal structures double shear is often limited by bearing on the central leg (the one holding 2P) and so can be less than 2*single shear.

trpile shear means (to me) that there are three shear planes carrying the load (one lug in double shear, one in single)

Quando Omni Flunkus Moritati