Eccentric Loading of bolt groups

[shaneelliss]

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.

 

[shaneelliss]

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.

 

[woodman88]

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

 

[Lion06]

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.

 

[HouseBoy]

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.

 

[msquared48]

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

 

[shaneelliss]

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.