Can i change the effective depth for reinforcement

[mnerva]

lovely friends
i have a flat plate ,it casted over a concrete plate form can i consider the reinforcement in the lower plate as assistant to the reinforcement or i cant

 

[mnerva]

dose the eurocode accept that

 

[wildehond]

in my opinion, you certainly can but you would have to be certain of a number of things: 1. is the flexural reinf in the bottom plate sufficient to cover the bend mom of the new combined slab. If not, you have to consider the 2 plates seperately as else your crack widths in the bottom plate would be excessive
2. can you connect the 2 plates adequately in shear to force the 2 plates to work compositely