The structural frame shown in Figure Q$3$ is rigid jointed and fixed to its supports. The mass of the structure is $5000$ kg and is concentrated on the beam that is assumed to be rigid. The two columns are assumed to be mass$-$less and each has a flexural stiffness $($EI$)$ of $4\mathrm{.}5$x$106$ Nm$2.$ If the structure has a damping ratio $(\backslash$zeta $)$ of $10\%(=0\mathrm{.}10),$ calculate; $($a$)$ the undamped natural frequency and $($b$)$ the damped natural frequency.