Use of structural monitoring in simulation of train-bridge interaction

This paper deals with possibilities and a case study to complement dynamic Finite-Element simulations of railway bridges with structural monitoring. A case study is presented for the Saimaa Canal Railway Bridge, Finland. During the train crossings, this single track bridge, 186 m in length, vibrates harmfully in lateral direction. These vibrations need to be controlled especially due to the fatigue issues in the overhead contact lines. The simulation consists mainly on two efforts: to create dynamic lateral load model that reflects reasonable well the theoretical and experimental work done for the railway vehicle dynamics on straight track; and to calibrate the open parameters of the load model with short-term structural monitoring. The simulation revealed that due to the tall piers, the lateral fundamental lateral natural frequency of the bridge is low, of order 1 Hz. The relatively small periodic forces due to the Hunting motion of wheel sets are enough to excite the bridge, and especially the overhear contract lines. Inversely, the measured lateral vibration of the bridge gives understanding of these forces that appears not to be widely addressed in bridge engineering.