Truss Plate Moment Capacity

[SASteve]

It would be great if somebody could point me in the direction of any documents related to estimating the in-plane moment capacity of metal truss plates for wooden roof structures. I was hoping that I could find a method of quickly, and relatively accurately, assessing the moment capacity of the contact areas for each member at a joint.

I am researching wind effects on residential structures and need rough capacities to identify the locations of probable failure initiation.

 

[KootK]

Good info here: Link

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.

 

[SASteve]

Thanks Koot!

I have been attempting to pick apart the Ma equation from the TPI Clause 8.7.1, but find it to be quite complicated. In the TPI 2007 Commentary I also found reference to the moment provisions from the previous version, where the applied moment was converted into an equivalent tensile force and compared to the tensile capacity of the joint.

Given that many of my modeled material properties are assumed according to our assessment of "typical" house construction, and that much of my analysis has been approximate to this point (working through an analytical "proof of concept" rather than a detailed assessment) I'm wondering if its worth my limited time to dive into the current provision or settle for a range of approximate values.

Any thoughts?

 

[Ron]

Why are you trying to develop moments in a wood truss with common truss plates? Simplify.

 

[SASteve]

I plan on analyzing the roof model using both pinned and rigid (separate cases) connection assumptions in hopes to get an envelope of the highest possible member end (joint) forces. Now I'm looking for capacity estimates to compare the extreme end moments and axial forces to, so that we can get a rough idea of the roof pressures/wind speeds & directions required to cause failure at each chord joint.

I also intend to neglect load and resistance factors to compare (estimated) true capacity to expected wind loads.

 

[KootK]

While I find the alternate method much more appealing to my intuition, I'd be inclined to go with the newer method. I can't see it taking more than 30 min to sort out. Especially if you're just going to be coding it into a spreadsheet anyhow. I doubt that either method is particularly accurate.

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.