Modeling Roof Decks in SAP2000 3

[KZSteel]

Does anyone know how to accurately model non-rigid roof decks in SAP2000? Specifically, I am trying to model 38mm Canam P-3615 roof deck. Here it is:

http://www.canam-steeljoist.ws/

http://www/v4/ecanamj.nsf/steeljoist/tablier#steeldeck

How do I set the property/stiffness modifiers when defining a section to model the deck as a non-rigid diaphragm?

KZ

 

[Ron]

I don't use SAP; however, when I model roof decks I treat them in two separate ways...for non-diaphragm, I model them as flat plates, just transferring wind load. If diaphragm, I model them as closely spaced beams using the properties of the decking (12" wide beams on 12" centers")

 

[KZSteel]

That's kind of what I'm doing right now... still, there has got to be a way to model a standard roof deck, otherwise it seems like a useless feature of SAP.

KZ

 

[slickdeals]

If you want zero diaphragm action and only need the deck to transfer forces from gravity and wind, then I would set the f11,f12 and f22 modifiers to very small values. I would model the deck as a membrane so that it will have no out-of-plane bending stiffness.

But remember that the roof deck will act as a diaphragm albeit, a flexible one.

 

[KZSteel]

I'll give that a whirl, thanks slickdeals.

 

[Gumpmaster]

You can set the thickness or modulus of elasticity of the deck to give you equivalent diaphragm response (gravity response shouldn't matter much). If you calculate the in plane stiffness of the deck from the manufacturer's literature, you can calculate an equivalent thickness of steel to give the the same stiffness, and then model the diaphragm as a flat plate.

The only problem is that beams connected to the deck may act as a Tee beam, composite with the decking.

 

[Gumpmaster]

Check out an example in Appendix A here.

http://communities.bentley.com/prod...ign__Wiki/ram-ss-semirigid-diaphragms-tn.aspx

It's not SAP 2000, but the fundamentals are the same.