Metal Plate Connectors in Existing Truss
Metal Plate Connectors in Existing Truss
(OP)
I’m looking at some existing 2x4 wood floor trusses. I need to come up with an allowable load for a client that wants a change of use (which will require a larger load.) Now I already know the answer: the trusses aren’t gong to have the extra capacity (125% of what the original should have been) because designing exactly to what’s needed is how the truss manufacturer makes money. But just for the sake of due diligence, I’d like to come up with a number for the guy. Obviously getting stresses in members isn’t tough. However, I’m not sure how to evaluate the connections. Short of tracking down the manufacturer, is there a good reference for the evaluation of metal plate connectors?






RE: Metal Plate Connectors in Existing Truss
http://www.tpinst.org/my_pubs.html
RE: Metal Plate Connectors in Existing Truss
RE: Metal Plate Connectors in Existing Truss
Now usually, a good engineered product would have its connections be stronger than the members...you could assume that the weak link is a member - analyze the truss and find that member and thus have a truss capacity. But as an engineer, you really can't certify a truss based on this assumption.
One thought would be to suggest that the plate connectors would provide 75% of the member capacity, but again - this is a guess and I would hesitate to use this in a report to a client.
RE: Metal Plate Connectors in Existing Truss
RE: Metal Plate Connectors in Existing Truss
I did manage to track down the truss fabricator and we determined that the connections are going to govern the allowable load and there is, as I expected, no extra. It makes sense that the metal plates are almost always going to be the governing component. After all, the wood is generally limited to one or two sizes (i.e. single or double 2x4) and maybe 3 available species/grades, whereas there are a lot of possible sizes for the connectors, and a lot of connections in a single truss.
Again, thanks for the direction.