Q$3)$ P$($t$)=$sinwt

W $($kN$)=750$

L$($m$)=4$

E $($MPa$)=26000$

I $($m$4)=0\mathrm{.}0006$

Stiffness and mass matrices of the following $3$DOF frame system

are given below. By using the static condensation method, remove the

rotational DOFs from the system stiffness matrix, and derive the equations of

motion in terms of the translational DOFs.