The French territory railway bridges are in large part masonry ones. Their behaviour must be understood to improve the risk management plan of such structures, particularly under natural hazards like seismic loadings. However, the modelling of masonry structures remains a significant challenge due to the complexity of such structures, mainly because of the age effect and changes in mechanical properties. So, strategies are required to avoid strongly increasing the computation times while modelling enough physical phenomena. In [1], a continuous model is proposed considering orthotropic damage coupled with friction. Mainly, this model accurately reproduces hysteretic loops in the case of cyclic shear tests. In this paper, an integral masonry bridge is modelled using the quasi-brittle continuous model developed in [1]. The aim is to evaluate the bridge damage level and the failure risk considering different evolution of mechanical properties and using the same seismic scenario. A real bridge with two arches, inspired by the work of [2], is considered and modelled using the finite element software Cast3M. First, numerical damage levels are imposed on the bridge to characterize its critical areas when submitted to quasi-static loading. Then, a breaking criterion is defined, and seismic computations are performed with a large set of signals to define the evolution of the estimated bridge fragility curves as a function of the initial damage state.