Problem $2$: Construct the $66$ stiffness matrix for the frame's element $1-3($only$),$ where the axial effects are included, using the Young's modulus $1\mathrm{.}2*{10}^{11}Pa,$ cross$-$section area $0\mathrm{.}01m^2,$ area moment of inertia $0\mathrm{.}0003m^4,$ and element length $0\mathrm{.}6m.$