Truss connector plates

[mjr6550]

I am trying to determine the manufacturer of truss connector plates used in dimensional lumber roof trusses built in 1994. The only marking on the plates is 8D-4. The plates are a relatively common design, but the designation does not match any plates I am familiar with. I have contacted one manufacturer and the Truss Plate Institute so far, and they were unable to identify the plates. Anyone recognize that designation?

I should mention that one reason I am looking for information regarding these plates is that many of the plates have partially withdrawn from the wood. Some plates are cupped and some have even fully withdrawn. I have seen partially withdrawn plates many times, but never this many or this much average withdraw. One thought was defective plates, but I have seen dozens of houses in the same development and other developments built by the same builder and this is not a common condition. My thinking as of now is that it is moisture related. There was evidence of excessive moisture accumulation in the attic (stained and discolored roof sheathing).

 

[XR250]

What are you going to do with that information? Might as well just add some gussets and be done with it. I have seen plates withdraw do the significant changes in wood moisture content. The shrinking and swelling supposedly can make the plates back out.

 

[mjr6550]

I was looking for the information for two reasons. I was curious as to whether there was some problem with these plates, which I did not really think was likely. The other reason was to obtain design data for the plates. This project has about 5 different truss designs and several are complicated designs. Measuring the trusses to come up with forces would take quite a bit of time. When I have plate details I usually determine the plate area at each member/joint and design the gussets to exceed the design values for the plates.

BTW, I did find out that the plates were made by Alpine. I contacted them and have not received a response yet.

 

[XR250]

You should be able to ballpark the forces in the members pretty easily.
I think truss plates have about an 80 psi capacity. Let me know what you find out.