A high-speed train passing a bridge structure at a critical speed can induce large bridge vibrations. In particular, the acceleration of the bridge deck is a critical design parameter because exceeding the normative limit can cause ballast instability resulting in track misalignments. Therefore, it is of utmost importance to realistically predict the acceleration response of the bridge in the design process based on a sufficiently accurate yet computationally efficient mechanical model. In engineering practice and research, a variety of modeling strategies exist with varying degrees of sophistication. For the structure, these can range from simply supported Euler-Bernoulli beam models that capture the bridge to two beams representing the structure and the track separately that are coupled by vertical and horizontal spring-damper elements, to sophisticated 3D finite element models that capture the components of the bridge and the track (and possibly the subsoil) in detail. The train modeling strategy ranges from single loads to detailed train models with multiple DOFs. Many bridges are single-span structures, but especially high-speed railway bridges span large valleys and thus consist of several single-span structures of the same length, weakly coupled by the superstructure of ballast and rail. The objective of this study is to evaluate the effect of different modelling strategies on the numerical prediction of the dynamic response of such weakly coupled ballasted bridge structures. In particular, different beam models with and without soil-structure-track interaction as well as with and without consideration of the weak coupling between the adjacent bridge structures are considered. The results of deterministic (semi-probabilistic) analyses and probabilistic failure assessments are performed and compared for the different models.