Wood floor on steel joists
Wood floor on steel joists
(OP)
I need to design a mezzanine system that will consist of a wood floor on open-web steel bar joists. The project is a new mezzanine inside of an existing building and I have calculated the required seismic loads on mezzanine. I have calculated a maximum shear load of 80plf under the seismic loads (I think this is very small). I am planning on using a plywood floor to support the gravity and diaphragm loads. I can't seem to find allowable shear loads for a plywood diaphragm supported on steel members, is there such a table or am I approaching this the wrong way?






RE: Wood floor on steel joists
RE: Wood floor on steel joists
You might need a 3X wood nailer, full with of the top double angle section of the joist, with nelson sill plate anchors welded alternately to the top angles of the bar joists in order to attach the plywood to the joist.
Mike McCann
MMC Engineering
RE: Wood floor on steel joists
RE: Wood floor on steel joists
Link
In the details section (59 & 60) of the link above, they show the attachment of a nailer to the joists. Seems like overkill for your situation though. Especially if you're running the joists at 24" or 32" spacings.
RE: Wood floor on steel joists
My point is that I do not think that you can drill the top of the joist flanges without compromising them. You have to weld something to them as I suggested in bold above.
Mike McCann
MMC Engineering
RE: Wood floor on steel joists
RE: Wood floor on steel joists
My joist spacing is planned to be 2'-0" o.c with a few instances of 2'-1".
msquared48
I understand your concern with regards to compromising the TC of the joists..... however, this is really no different than screwing steel deck to the TC of a steel joist which, as far as I know, is allowed. In the details azcats provides in his post, the holes are pre-drilled into the TC which I would agree degrades the TC. However, with a self drilling screw, would your really be compromising the TC? Wouldn't you be replacing the material you took out with the shaft of the screw? and in a member that is under compression would this cause a problem?
RE: Wood floor on steel joists
But to be sure call Vulcrafts South Carolina office and talk to the Joist guru, Mr Mike Antici.
If i can specify to attach a metal deck at 36/6 with #12 screws to steel joists then i should be able to do the same thing with wood deck at 6" o.c... But spacing (the Field) attachment is still important in this configuration
RE: Wood floor on steel joists
RE: Wood floor on steel joists
RE: Wood floor on steel joists
Also - it might be wise to coordinate with the joist manufacturer no matter what connection you choose as there are likely bracing forces for the top chord of the joist than need to be resolved and I imagine that's not in your scope.
RE: Wood floor on steel joists
@azcats - I cant imagine 3/4" plywood not providing sufficient bracing for the top chords
RE: Wood floor on steel joists
RE: Wood floor on steel joists
RE: Wood floor on steel joists
RE: Wood floor on steel joists