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Floor Girders Carrying Roof Loads

Floor Girders Carrying Roof Loads

Floor Girders Carrying Roof Loads

Just want to confirm or get opinions on floor girders carrying roof loads in software.

Case has come up to debate by some people. Floor girder had floor members framing into it. It supports a wall which supports some roof trusses.

So in mitek software modeling a flat roof girder for a floor girder that carries both floor and roof trusses would be the appropriate way of handling it correct?

Doing it this way you would be able to analyze for all load cases including wind uplift effects from the trusses above at the appropriate DOL in my case usually (1.6 for wind or 1.25 for roof live)

Additionally, I would apply and wall weight that would bear on the girder and adjust the deflection criteria to that of a floor truss.

Does this sound appropriate or does anyone see any issues with this?

RE: Floor Girders Carrying Roof Loads

No reason not to design a girder truss to support roof, floor, and wall loads. I've done hundreds of them.

The only red flag I see is that you mention a flat girder. Keep in mind that the top chord of the girder must be restrained so it doesn't move horizontally. That's often not possible with a flat girder.

RE: Floor Girders Carrying Roof Loads

I agree with the redneck (ha!). Transfer floor trusses are designed regularly. It is good practice for the EOR to provide a section detail for each type of transfer truss and definitely provide the the point loads broken up into DL, L, Lr, S, etc. so they can apply the correct duration factor or use LRFD, etc.

That said, you do have to get a feel for the practical limits ahead of time, so that you don't get an RFI later on from the truss manufacturer that says they need 5 plies of trusses to make it work. I compare the floor only moments to the moments induced by the transfer loads, and get a feel for approx. how many plies would be needed. Of course, select structural lumber or a deeper truss (if possible) will help the decision.

"It is imperative Cunth doesn't get his hands on those codes."

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