A fractional derivative Zener (FDZ) model connected in parallel with a linear viscous damper and a Coulomb friction slider is used to numerically simulate the mechanical behavior of a base isolated (BI) building tested under free vibration conditions in Solarino, Sicily. This hybrid BI system comprises high damping rubber bearings in combination with low friction sliding bearings. A comparison study of the present model with previous ones appearing in the literature, namely the bi-linear and the tri-linear models defined in the time domain, is carried out here. Furthermore, the linear viscoelastic solid, namely the classical Zener model, is also implemented and evaluated. The rheological models representing all the above BI systems are analyzed and, for the first time, the rheological formulation for the tri-linear model is presented. The present comparison study shows that the FDZ model is capable of describing the complex nonlinear response of BI systems.