$($e$)$ Perform a preliminary design for a braced and non$-$slender Precast Reinforced Concrete $($RC$)$ square Column for $2$ hour fire resistance period $($with more than one side exposed to fire$)$ under ultimate axial load, $N_{ED}$ of $2500kN$ with nominal$/$minimum eccentricity, e as follows: Assume C$40/50$ concrete and steel reinforcement $($rebar$)f_{yk}=500$MPa.

$($i$)$ To cater for strength, compute the required minimum size of the square column based on Figure Q$-1($b$),$ assuming rebar ratio of $)=(2\%.$ Comment on the structural adequacy if a column size of $375mm375mm$ is to be provided keeping the rebar ratio constant at $2\%.$

$[3$ Marks$]$

$($ii$)$ In catering for fire resistance, state the appropriate Eurocode $2($EC $2)$ alternative$/$method A or B$,$ compute either the ratio of applied axial load with reference to its capacity $({}_{fi})$ or steel capacity$/$concrete capacity $()$ where relevant assuming a column size of $375mm375mm.$ Check and comment on the adequacy for $2$ hour fire resistance period for the column the minimum size calculated in $($e$)($i$),$ and for the column with the size of $375mm375mm.$

Marks$]$

Figure Q$-1($b$)$ Relation between size of square RC column vs ultimate axial load $($from The Concrete Centre, UK$)$