This paper deals with the evaluation of the main relevant properties of the double concave friction pendulum devices, namely DCFP, able to influence the seismic behaviour of infrastructures such as isolated multi-span continuous deck bridges. With this aim, a numerical model has been proposed to simulate the dynamic behaviour of seismically isolated bridges, and so an eight-degree-of-freedom system adopted in order to model the elastic reinforced concrete pier and the isolators devices. Furthermore, the interaction pier-abutment has been taken into account and the former modelled as a fully fixed restrain. The deck has been assumed rigid in its plane and a non-linear velocity dependent law adopted to model the friction along the two surfaces of the pendulum isolators. The equations of motion have been proposed in a non-dimensional form by means of a preliminar dymensional analysis. Finally, a widely parametric analysis has been conducted and record-to-record variability taken into account by using a set of natural records with different characteristics either in terms of epicentral distance and magnitude. The response of the system in terms of pier and deck displacements, is presented in a probabilistic fashion and as independent from the seismic intensity thanks to the abovementioned dimensional analysis. The main evidence of the study is how the main structural parameters involved in the analysis are able to control and influence the seismic response, such that the outcomes of this research could be used to better design or retrofit multispan coninuous deck bridges isolated with DCFP.