An upper office floor is to be an all$-$concrete monolithic beam & slab system. The floor slab is to span $1-$way & continuously over a number of rectangular down$-$stand beams at $2\mathrm{.}5m\frac{c}{c}$ which will themselves be simply supported over an $8m$ span between columns. Make rational choices for material properties, slab thickness and beam dimensions based on deflection & fire considerations, assuming "mild" internal exposure conditions and a $1-$hour fire resistance $($if you use the guide values below you must justify them first!$).$ Design the T$-$beam section for bending & shear.

$($Guide: $f_{ck}=25\frac{N}{m}{m}^2$;$100mm$ slab & $550mm(450$mm down$-$stand$)x200mm$ beams; for $LL$ of $3k\frac{N}{m^2},$ w beam $($:~~$23k\frac{N}{m}$;$A_s=2H25$&$A_{sw}=H8-375\}$