Wood I-Joist Bi-Axial Bending? 1

[meamin]

Hey everyone!

I have a question about I-joists. Client wants to use them as rafters, everything checks out. In my RAM Elements model, the rafters connecting to the ridge beam and valley beam are subjected to bending+axial. First of all what do you think of that? I'm still fresh out of school and my thinking is that this is ok as long as I design the connections for the forces. Plus it helps out with by reducing the size of Ridge Beam since these rafters are taking some of the load.

Anyways my main question is where to find values for the fc and ft of an i-joist? for example TJI i-joists list allowable moments and shear but do not list values to determine the axial capacity and therefore I cannot check the rafters for bending+axial.

I hope it's not because this is a big no no for I-joists. If it is, then I do not think it will be much trouble telling the client we should frame this with regular dimensional lumber.

Thanks!

 

[Ron247]

Call the I-joist supplier. I have seen them show these as rafters before in their literature. Typically, they were shown as a rafter to a ridge beam but I am sure they can work either way. I do not think it will reduce a ridge beam size. Do you have a ridge beam or a ridge board? Do you have ceiling joists tying the walls together? If you have a ridge board, it is not structural member anyway.