in the figure. The compression flange is effectively restrained over the span

and intermediate stiffeners are provided at $1\mathrm{.}875$ m centres between supports

and the centre load. Assuming that the plate girder and fire$-$protection casing

weigh $20$ kN$/$m$,$ carry out the following design work:

$(1)$ Check the adequacy of the section with respect to bending, shear and

deflection.

$(2)$ Design a suitable load carrying and bearing stiffener for the supports

and concentrated load positions.

$(3)$ Determine the weld size required at the point of maximum shear.