A study of the lateral dynamic behaviour of high speed railway viaducts and its effect on vehicle ride comfort and stability

The study of the lateral behaviour of railway bridges and vehicles is an important issue on bridges with low lateral stiffness, which has been defined by ERRI (1996) as those with lateral natural frequencies below 1.2 Hz. This limit applies to the deformation of the deck in one span, and was demonstrated to be a real issue on measurements and models of bridges with open deck sections and supporting trusses, of low lateral bending stiffness for the deck. Although not included in the above category, modern long viaducts for HSR with continuous decks on tall piers may also exhibit very low lateral stiffness and frequencies, which could produce undesired effects for the comfort or even the stability of the railway vehicles. In this work a simple model has been developed and applied to consider worst-case scenarios in a representative bridge, the “Arroyo de las Piedras” viaduct in Spain. The trains considered are representative of those circulating in the Spanish HSR network, as well as a freight wagon. Threedimensional dynamic models were developed with finite elements. The actions considered include the lateral deformation of the bridge in response to vertical eccentric loads, track alignment irregularities and finally lateral motion of vehicles due to conicity of wheel-rail contact. The results show that there is, at least in this case, no cause for concern. However, for some scenarios the results in terms of lateral motion and forces are not negligible and should be considered in the design