ABSTRACT
ABSTRACT: From experience, the control of the dynamic behaviour of rail bridges (deflection and acceleration) has proven to be a “since qua non” condition for the control of railway high-speed. Without it, not only the rail-wheel contactmight be rupturedwhen crossing the structures, but above all chances are that instabilities of the ballast railway might appear on and around the bridges and viaducts. The analysis of the behaviour of the latter using finite-element software allows avoiding such risks.Yet the use of computerized programs does not truly permit to underline the importance of the parameters that rule the phenomenon. Also, engineers do not have at their disposal all the elements permitting to guarantee a real conception: to understand why and how the structure reacts to the crossing of the trains, to know on which characteristic of the structure one has to work in order to modify its behaviour – or simply to foresee the latter (the behaviour) in the case of the degradation of one of his characteristics. Even several numerical simulations, may they be long and expensive, do not allow the total understanding of the train/structure interaction. When analyzing the excitation created by a train, it is possible to underline all the parameters that are useful to the control of the dynamic behaviour of railway bridges. The method presented in this work and based on the concept of the dynamic signature of trains (or their spectrum) allowed elaborating new regulations that were incorporated into the Eurocodes – in particular the universal dynamic train – as well as interoperability technical specifications (ITS) permitting high-speed trains to travel all over Europe. However, the knowledge of those different regulations is not enough to fully understand the phenomenon; only the process described in the present document permits to obtain such a result.
