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Separation between anchor bolts

Separation between anchor bolts

RE: Separation between anchor bolts

Depends on where your project is located. If in the US then I'd say AISC Design Guide 1 and ACI 318 Appendix D. Is this a moment connection or is this assumed to be a pinned connection?

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com

RE: Separation between anchor bolts

Other than practical limits, that won't govern from a design perspective, there are no regulations on minimum bolt spacing. Spacing is a thing that is a part of an overall anchor bolt design for capacity.

RE: Separation between anchor bolts

(OP)
Pinned connection

RE: Separation between anchor bolts

If it's a connection that you'll design for a particular moment or uplift, then concrete breakout may well govern and I'd refer you to the same references that TME did. If there's no specific design moment or uplift, then your primary concern will be erection stability and the associated OSHA requirements (US). For erection stability, you probably want to spread your bolts out as much as possible without getting yourself into trouble with wrench clearances etc. That said, you typically see nice round numbers for X like four or six inches depending on the space available between flanges.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Separation between anchor bolts

(OP)
The idea is a pinned connection thus the foundation is small.

RE: Separation between anchor bolts

If pinned and you don't need uplift or lateral load capacity (like for an exterior column) then similar to KootK I'd go for largest spacing practical, even numbers, and ensure you have sufficient entering and tightening clearance for the erector. Oversized holes and plate washers will help the contractor out a lot with field adjustment.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com

RE: Separation between anchor bolts

ACI 318-11 section D.8 has minimum spacing requirements for anchors. It is not much, (4 to 6 anchor diameters with some exceptions).

RE: Separation between anchor bolts

(OP)
I'm designing an steel structure of variable section, I'm worried for this: Collapse of Steel Structure

RE: Separation between anchor bolts

That kind of thing has much more to do with proper erection bracingI believe.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Separation between anchor bolts

By all means run an analysis on a partially built frame and check that your bolts have sufficient capacity. But, as KootK indicated, that was almost assuredly a failure to brace the frames and provide lateral support; not something you should be relying on your anchor bolts to do.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com

RE: Separation between anchor bolts

(OP)

I understand that to ensure good anchorage must use greater distances between bolts, if possible, that they're located outside the section of the column, so, Can I take it as a rigid connection?

RE: Separation between anchor bolts

Only if your base plate, welds, and concrete can have sufficient strength/stiffness for the moments you'll be applying.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com

RE: Separation between anchor bolts

If you're bound and determined to use fixed base connections as your temporary bracing, I would:

1) Consider your loads carefully, particularly P-Delta effects.

2) Give account the rotational flexibility of your base connection, no mtter what you do with the bolts.

It's serious stuff as the example you posted highlights.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Separation between anchor bolts

(OP)
Thanks for all. I will publish the results.

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