2021 IBC 704.3

[eatapeach]

704.3 states that the primary structural beam must be individually encased to achieve a rating. How is this performed when a fluted deck is placed over the beam and filled with concrete? I know some folks will say the concrete slab provides a rating; however, this is not what the code states. 704.3 Commentary indicates that the beam must be protected independently. Therefore, how is the top side rating achieved?
This is a three-story building supporting a roof for code purposes.

 

[HTURKAK]

Therefore, how is the top side rating achieved?

My interpretation is , top side is not exposed to the fire directly so some folks which are arguing 'the concrete slab provides' , is reasonable . The following figure from 2018 International Building Code Illustrated Handbook.

 

[eatapeach]

Yes, that sounds reasonable since the 4" slab has a one-hour rating. I'm not sure if I would have accepted it had the floor above not been rated.

Thanks for your input.