Bolt holes 2

[tvar]

Hi,
Has anyone ever come up with the situation where you have steel coming from over seas with metric bolt holes and the design was for imperial bolts? My question, the holes for 3/4" A 325 bolts in a bearing connection are 22mm (7/8") where by code they should be 21.4mm(13/16"). An oversize hole is 24mm (15/16")Is this an acceptable for a bearing connection?

 

[alexit]

I have much coming from a particular large asian country, earlier many features were sized differently than I intend. I solve this until now by ordering with smaller holes that we can finish to size where important. Otherwise I take the bigger holes and feel good that bolts fit at all...you ever (try) put together outdoor furniture?

I dont have bearing connection codes, is 22mm outside max tolerance for 21.4mm design?

 

[diamondjim]

Are you talking about one hole being oversize
in a pattern of holes? Can you use
a 7/8 bolt instead of 3/4? Are you using
heavy washers under the bolts? I would expect
them to use a 21mm dia drill for a 3/4 bolt
in Europe.

 

[Ussuri]

A 22mm clearance hole is the normal size for an M20 bolt. The equivalent oversize hole for an M20 is 25mm.

 

[RHB51]

We run into this commonly when designing spreader beams;
small bolts/pins with an oversized hole. If you want more information please advise and I will have one of my staff engineers get you in the right direction.

 

[Torquester]

The conservative answer is you no longer have a bearing connection, but a slip-critical one. The hole sizes listed in Table J3.3 are "maximum" sizes for normal sized holes.

Similarly, contractors sometimes claim that all holes are 'standard' size provided they stop just short of the specified size for an 'over-size' hole, as when holes doen't line up and they ream them.

In practice, anything over the maximum size of an AISC normal hole is to be treated as oversize.

 

[tvar]

Thanks for your responses. This project is in NYC which does not use current codes.??? I'm not sure how they solved the problem I was just asked to look at it, I did the foundation design and the person reviewing the structural passed away. CSA-S16.1-94 (Canadian Steel Spec.) Section 23.3.2(e)gives bolt and hole combinations for bearing and slip critical connections "(i) either a 3/4 inch diameter bolt or an M20 bolt in a 22mm hole". That's the only reference I found.