Problem:

If the allowable bond stress is exceeded at SLS does composite action have to be ignored ?

Solution:

If the size of the concrete compression flange is reduced then the bond stress is also reduced. I have found that by considering only part of the concrete that is available then composite action can be justified at SLS. The increase in the bending capacity of the steel beam at ULS by considering composite action with the reduced concrete flange has often proved sufficient to justify a higher live load rating.