Section properties for composite slab with steel deck

[avecillasjavier]

Hi everyone. I'm doing a seismic design of a 10 story steel building with composite slabs and i want to know wich are the best properties modifiers to get the more accurate period of the structure. In my first analysis, i used f11, f22, f12, m11, mm2, mm12 = 0.25 but i'm not really sure about these properties modifiers because i have not much experience in this kind of composite slab.

 

[neznajko]

Please first make sure if you should use the composite deck as rigid/ semi-rigid or flexible diaphragm.

If you can use the deck as rigid diaphragm and you are using the results only for lateral force distribution you can use 1 for everything. If you are using the model to check DL/LL deflections - just modify the ms. The diaphragm action of the deck should not be influenced from the cracked section modulus of the slab.

 

[avecillasjavier]

neznajko thank you for your answer. I'm using the period only for the lateral force distribution. The problem is that i'm using the composite deck as semi-rigid diaphragm. Any suggestions about this case?