Plywood Gusset Plate Design for Wood Truss

[JrStructuralEng]

Hi,

I a couple general questions about designing plywood gusset plates for a wood truss for a double garage.

1) How do I determine the thickness of plywood requried, and nail spacing. I am designing based on single shear, however, there must be some determining factors on how close the nails can be to the edge of the plywood and/or how close together they can be. I am assuming no closer than 2" o.c. (Staggered) I am also assuming 5/8" to 3/4" how I am unclear on how to determine the shear/tension/compression capacity of plywood in order to determine the thickness.

2) I was planing on using common nails. Do I have to use something that grabs more like ring nail/concrete nail or wood screws?

If anyone can help me that would be great. If possible, it would be great to have someone walk me through how they would go about designing this connection.

Thanks!

 

[Lion06]

This is not a common connection since most wood trusses are manufactured using metal plate connectors.
For your situation, I would look in the plywood design specification (you can find it at the APA website).
Also, I had a desire to find this out some time ago (purely for my own knowledge) and I ended up emailing the APA. Even though they didn't have any design guidance listed as public, the nice lady I spoke with faxed me a couple examples that had been submitted to them. It was a little hard to weed through at first, but was very helpful.

 

[JrStructuralEng]

Thanks for the response!

When I look at the plywood design specifications. What type of shear am I concerned with when trying to figure out nail spacing from edge,etc.

 

[Lion06]

It depends on your particular loading conditions and orientation of the plate with respect to the truss members, but both parallel to and perpendicular to grain should apply at different locations in the plate (assuming you have members coming in perpendicular to each other).

 

[MiketheEngineer]

I would strongly suggest you go ahead and buy prefabbed trusses.

The time you save will more than pay for any savings.

Also - by the time you get all the nails in the 2x4 members - you may have shredded them.

When you go to re-sell - some people will look at this construction as sub-par.