A superstructure made up a deck $10m$ wide supported on two sides $3m$ deep

$($distance to the main deck$)$ is to be included for strength purposes.

The original section properties are

If the total cross section area of the stiffeners for the sides and top is $0\mathrm{.}003m^2,$

determine the minimum thickness for superstructure plating in order to keep the stress

below the level obtained without the inclusion of superstructure.

Plating thickness, stiffener spacing and cross section area of stiffeners are assumed to

be the same for the sides and top structure.

$[t2\mathrm{.}024mm{]}_{?}$