A single storey single bay portal frame supports a machine which exerts a horizontal force at girder level, F$($t$)=200$ Sin$(5\mathrm{.}3$t$)$ N$.$ Assuming $5\%$ critical damping, determine i$)$steady state amplitude of vibration and maximum dynamic stress in the columns. Assume the girder is rigid.Given data m$=100$kg$,$ length of each column $3$m$,$ cross sectional area of column

$=300$mmx$300$mm