Effective Fasteners in Wood Dowel Splice Connection Rows 1

[MacGruber22]

Is anyone aware of any documentation that discusses limitations on the number of dowel fasteners in a given fastener row? Intuitively, there has to be a practical distance by which the fasteners become increasingly ineffective at sharing the force along the row. Of course, there are ways to avoid having to be concerned with this. It is a bit more of a theoretical question in order to prove a point that someone else's splice connection was not only inadequate but impractical. Thus, it would be nice to have a solid reference.

-Mac

 

[KootK]

Group action factors?

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.

 

[dhengr]

MacGruber22:
End distance, edge distance, spacing btwn. bolts/dowels, angle w.r.t. the grain, etc. all come into play. And, finally due to fab. tolerances all of the dowels don’t come into play at the same time, when the loading is applied. Thus, you shouldn’t just divide the load by the number of fasteners. I don’t have the latest eds. of the NDS, Koot’s table looks like the right starting point. I would look at the bolted connections section of the NDS, the commentary and a couple good wood design texts to frame your argument.

 

[MacGruber22]

Yes, that is it. Ugh...It has been awhile since I had to do a wood connection. I already worked out the spacing and edge/end distances to get the geometry factor to 1.0, but I knew I was missing something.

-Mac

 

[MacGruber22]

Also, I had meant to say that this was with respect to fasteners with diameters less than 1/4" (wood screws). The unlimited # of fasteners in a row without reduction in the group factor still doesn't seem reasonable to me. I feel this is particularly true when it comes to maintaining the stiffness of the splice in a moment connection. I would think you would want to limit the length of the rows to the depth of the member (or maybe at most 1.5*depth). When you try to splice a 2x8 joist at mid-span with a wood side member, the row lengths get out of hand. Adding additional rows in a 2x8 hurts more than it helps too. I would never want to do this - a contractor tried to pull it off, and now we are trying to explain why it doesn't cut the cheese.

-Mac

 

[dhengr]

MacGruber22:
What a gigantic design consideration to neglect to mention. Quit thinking so quickly/loosely or thinking out of your butt. Those connectors do not have the hole tolerance for bearing issue, but the still have spacing in the row issue. And, sooner or later the number of fasteners in a row will induce splitting/horiz. shear failure in the line of that row. So, your 1 to 1.5 times the member depth might be a reasonable place to start in terms of max. row length, spacing still to be determined. This might be something that the fastener supplier should evaluate in an ICC-ES evaluation testing program. They could/should show the reduction in fastener cap’y. after some number of fasteners in a row, at such and such spacing, in a particular density wood.

 

[MacGruber22]

Quit thinking so quickly/loosely or thinking out of your butt.

Fair enough.

-Mac

 

[KootK]

I thought that we were talking tension splice. For moment connections, a long connection makes sense. Firstly, your fastener loads are mostly transverse to the member so length effects don't really come into play. Secondly, a common design approach relies in the fastener sub groups at the ends acting as effectively seperate groups forming a moment resisting couple.

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.

 

[dhengr]

MacGruber22:
In many cases smaller dia. and greater in total number of fasteners is a good thing, assuming you pay attention to spacing, splitting and some form of horiz. shear failure..