Dynamic response dependency on the travelling load direction for a multi span cable system by operational modal analysis

The dynamic response of a cable system under travelling load is important for the interaction between the load and the cable system. Railway catenary systems are such cable systems loaded by the passing train. The travelling load is then a contact force arising from the pantograph-catenary interaction. The interaction is crucial for the power supply of the train. This is dependent on the interaction between two non-linear dynamic systems; the in space stationary catenary system, and the moving pantograph. The pantograph are mounted on top of a train, and may often travel along the catenary in two different directions. It is therefore likely that the dynamic response is dependent on the loading since the cable system is only symmetric in one span, not over many spans. This paper primarily explores the difference in dynamic response of a railway catenary system due to the travelling direction of a train by operational modal analysis. Sampling of accelerations from several successive spans under loading from regular traffic has been performed, and the time series has been analysed and compared using operational modal analysis.