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Eccentric Loading of bolt groups

Eccentric Loading of bolt groups

Eccentric Loading of bolt groups

(OP)
Anyone know where there is any guidance on how to handle eccentric loading on bolt groups in wood beams?  I don't see anything on it in the 2001 NDS but maybe I am missing something.

RE: Eccentric Loading of bolt groups

(OP)
I guess to add a little more info, I am talking about designing something similar to a beam being cantilevered from another beam or column and connected to the supporting member by a group of 4 or 6 bolts.  I want to know how to determine the load capacity of the bolt group.

RE: Eccentric Loading of bolt groups

In theory you can apply the Hankinson Formula (See the NDS Appendix J) to the wood and bolt values to determine the required connection. I see the possibility of splits occurring in the wood members as a failure mode. For this reason I prefer to add tie bolts (perpendicular to the moment bolts) with a tack welded nut (or strike the threads) to hold the wood member together, in case of member splitting.

Garth Dreger PE
AZ Phoenix area

RE: Eccentric Loading of bolt groups

It seems like a simple elastic bolt group analysis.  Any good steel textbook would have this.

That being said, fixed connections are difficult to achieve in wood.

RE: Eccentric Loading of bolt groups

Like SEIT wrote, that is usually how I do it too.
Thing is, you've got to place the bolts pretty far apart to get decent moment capacity. This means, there is substantial overlap.
Other than that, it works fine.

 

RE: Eccentric Loading of bolt groups

Try to come up with a connection where the bolt group does not have to transfer moment.  Perhaps an additional strap or some form of bearing plate addition could accomplish this.

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: Eccentric Loading of bolt groups

(OP)
Thanks for the responses.  Time to get out the steel manual I guess. That was actually my first thought, but then I wondered if the wood code had anything on the subject and thought I would ask the experts.

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