Split Rings In End Grain Sloping Cut

[stennist]

I am looking for some advice on the use of split rings in the end grain of a timber member. I am designing a king post truss in which the top chords will bear against each side of the king post. I want to use 4" split rings to transfer the load between the chords and the king post. I understand how to calculate the strength of the split rings, but the code (NDS) is not very clear about edge distance, end distance, and spacing for these connectors in the end grain. The angle of cut to the grain in my particular truss is 63deg. Section 12.3.6 states to apply provisions for perpendicular to the grain loading for sloping surfaces with alpha between 45deg and 90deg. The top chords of my truss are 6x8 DF-L timbers and the split ring will be centered in the member. I know that my distance to the loaded and unloaded edges (at bottom and top of cut) is about 4.25". What I am not understanding is what my end distance is? Would this be the distance to the edge of the member(5.5in/2 = 2.75in)? Or is end distance ignored for this situation. Thanks in advance for the help and advice.

 

[DBronson]

stennist:

I think your confusion comes from the sense of the terms as used in this situation - looking perpendicular to the end cut: the edge distance is the horizontal distance from the center of the split ring to the sides of the timber. The end distance is the vertical distance from the center of the split ring up to the top of the cut and vertically down from the center to the bottom face of the member. In other words, if I'm understanding your description, the edge distance is 2-3/4" and the end distance would be ~10" assuming the ring lies on the centroid.

If you can find a copy of the 3rd edition of the Timber Construction Manual there's a diagram on page 6-440 that shows this condition. There's an example problem there as well.

Regards,

DB

 

[stennist]

DB,

Thanks for your quick and thorough response. I could not find a copy of that particular edition. The method you suggest is similar to the design example from older versions of the NDS. In that example, the angle of the sloped cut was less than 45deg however. When the angle is less than 45deg you are supposed to follow provisions for loading parallel to the grain. In that case the edge and end distance would be as you suggested. Can you confirm if your example has a angle of cut to the grain less than 45deg?

You did lead me in the right direction. I just purchased a copy of the 6th edition. This edition gives very detailed equations for determining edge distance, end distance, and spacing requirements for split rings in the end grain. The distances end up somewhere in between parallel to the grain and perpendicular to the grain loading conditions. This manual looks to be a great edition to my library. Thanks for directing me towards it.

 

[DBronson]

stennist:

The angle (alpha) of the cut is 26.565 degrees (24/12) in the example problem in the manual.

Regards,

DB

NB: I can try to post a photo of the sketch if you still need it.

 

[stennist]

Thanks DB. I think I have it figured out now. The 6th edition of the Timber Construction Manual goes into the design in the end grain in really good detail.