The steelwork in a structural frame includes simply supported braces and beams and will carry lateral design loads of $P^{*}=520kN$

at points E and D$.$ Columns AC and FD are designed from $200200$ square hollow sections. The connection of braces and beams to

the columns are "simple" connection $($unable to transmit bending moments$)$ and other frame dimensions are $a=1\mathrm{.}8m$ and $b=3\mathrm{.}5$

m$.$

The beams and braces are required to be fabricated from cold$-$formed $($non$-$stress relieved$)$ grade $350$ rectangular hollow sections

$($RHS$).$ There is sufficient lateral restraint perpendicular to the braces and beams $($i$.$e$.$ out of the plane of the page$)$ and buckling will

happen around the major axis of section. For the purpose of this question, consider only members CD and CE:

a$)$ Calculate the axial forces generated in each member $($CD and CE$)[$hint: CD undergoes tension and CE undergoes

compression.$]$

b$)$ Propose a suitable section for member CD$.$

c$)$ Check whether a $1501006$ is suitable for member CE$.$

Notes:

If you have been unable to determine the design forces, use a value, say, $550$ kN to allow you to move onto sizing the

member.