metal deck diaphragm as continuous tie

[danvines]

I have a warehouse/industrial building that is load bearing tilt-up with joists and metal deck. ASCE7-05 12.11.2.2.4 disallows the use of the deck as the continuous tie between diaphragm chords in the direction perpendicular to the deck span. This makes perfect sense, as the deck would buckle easily across the flutes.

This paragraph leads me to believe that the metal deck CAN be used as the continuous tie PARALLEL to the deck span. However, I can find no published information on what loads the deck can actually handle in this situation.

Any suggestions? I really do not want to start adding sub-diaphragms and struts willy-nilly if I do not have to.

FWIW, this building is an SDC C. The roof deck is type B, mixed 20 and 22 gage.

Thanks
Dan

 

[haynewp]

I have looked before and I couldn't find values either. You may can approximate something using AISI knowing the deck profile.

 

[RacingAZ]

The joists are typically your continuous ties for the direction perpendicular to the deck span.

For the direction parallel to the deck span, you can use the deck as your continuous ties. If you're in the high seismic or high wind area, there is really no way around it without adding struts at every so often as the loads will exceed the deck capacity to work as ties. There are also building departments that probihits this approach (LA is an example, Miami is another). What you're looking for is unpublished info that you can get if you call the in-house engineer for a deck manufacturer. I remember getting one a while back from Verco but don't think that I have a copy anymore.

 

[TTUengr51]

Due to the out of plane seismic attachment requirements for tilt-up panels, I typically use angle cross-ties between bar joists when the wall runs parallel to the joist framing. I continue these back far enough to create a sub-diaphragm that spans between my supporting joist girder/beam line and then use that line as my continuous tie.

For a large warehouse/industrial type building, I normally will orient my last bay of joist framing to be perpendicular to the wall so I have the tilt-up panels tied into the diaphragm. That way I only have the corner bays requiring the cross-ties I mentioned above. (see attached file for example)

Nick Deal, P.E.
Michael Brady Inc.

http://www.michaelbradyinc.com

 

[haynewp]

The only thing I don't like about re-orienting the joists is that you have to change the deck direction at multiple locations around the roof.