QUESTION $2[25$ MARKS$]$

Determine the factored compressive resistance, $Cr,$ of a $5m$ long strut manufactured from a $15015010$ equal leg angle $($with yield strength $fy=350$MPa $).$ The strut is pinned at its ends, and bracing provides lateral restraint to the $y-$axis at mid$-$length.

$1$ Questions were derived from GK Parrot: Structural Steel Design to SANS $10162-1$:$2011,2^{nd}$ Ed Version $7(2019)$