Transmissibility, in the context of structural dynamics, can be defined as the ratio of the maximum force ( f m a x {\displaystyle f_{max}} ) on the floor as a result of the vibration of a machine to the maximum machine force ( P 0 {\displaystyle P_{0}} ):
T R = f m a x P 0 = R d 1 + ( 2 ζ β ) 2 {\displaystyle TR={\frac {f_{max}}{P_{0}}}=R_{d}{\sqrt {1+(2\zeta \beta )^{2}}}}
Where ζ {\displaystyle \zeta } is equal to the damping ratio and β {\displaystyle \beta } is equal to the frequency ratio. R d {\displaystyle R_{d}} is the ratio of the dynamic to static amplitude.
Further reading Vibration Control and Measurement Tech Tip: Spring & Dampers, Episode Four
References