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Split ring failure

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I had a brief look at some roof trusses that were field fabricated some time around 1960.  I think they were split ring connections, although I’m not 100% positive about that.  I done some research on them and I’m going back for a second look.  I wanted to get some information from some of you who may have experience with split ring repair.  The trusses have started to fail.  The bolts are failing in shear at the end of the lumber.  The wood has sheared at the bolt hole with 2 shear planes the diameter of the bolt between the bolt hole and the end of the lumber.  A “plug” of wood is sliding out the end.  The bolt is ½” diameter.  I didn’t measure the ring size yet.  The connection is a single shear type connection with one split ring.

 

Is this a common mode of failure for a split ring connection?  What are the recommended methods of repair?  I was considering using lag screws to replace the split ring but the shear value of the lag screws is not sufficient in the quantity I could fit on the lumber.  If I lagged around the split ring to compress the lumber together where the ½” bolt failed would that help reinforce the original split ring design?  Are there any published studies on repairing split ring connections?

 

Thanks.

 

 

Rich Lewis

Lewis Engineering