$(20$ marks$)$ Design an interior flat slab with columns at $6\mathrm{.}5m$ centres in each direction and supports an imposed load of $4k\frac{N}{m^2},$ as shown in Fig. $1-3.$ The characteristic strength for materials are $f_{cu}=30\frac{N}{m}{m}^2$ and $f_y=500\frac{N}{m}{m}^2$ for the reinforcement. The overall depth of slab is $250mm$ and the drop panels are $2\mathrm{.}5m$ square by $100mm$ deep. The effective diameter of column heads is to be $1\mathrm{.}4m.$ The concrete cover to reinforcement is $25mm$ and the preferred bar size is $12mm$ in diameter.

$($a$)$ Determine the design load for the flab slab.

$(2$ marks$)$

$($b$)$ Determine the width for column strip and middle strip.

$(2$ marks$)$

$($c$)$ Evaluate the moments at interior span and interior support for middle strips and column strips.

$($d$)$ Design the reinforcement for the strips.

$(4$ marks$)$

$($e$)$ Check for punching shear at face of column and $1\mathrm{.}5d$ from column face.

$(5$ marks$)$

$($f$)$ Check for deflection adequacy.

$(4$ marks$)$

$(3$ marks$)$

Fig. $1-3$ Reinforced Concrete Flat Slab

Table $1$ Moment and shear force for flat slab design

$\backslash$table$[[,\backslash$table$[[$At outer$],[$support$],[($simply$],[$supported$)]],\backslash$table$[[$Near$],[$middle of$],[$end span$]],\backslash$table$[[$At first$],[$interior$],[$support$]],\backslash$table$[[$At middle$],[$of interior$],[$span$]],\backslash$table$[[$At interior$],[$supports$]]],[$Moment$,0,0\mathrm{.}086FL,-0\mathrm{.}086FL,0\mathrm{.}063FL,-0\mathrm{.}063FL$