Monitoring of Interaction between Railway Superstructure and Bridge

Monitoring of Interaction between Railway Superstructure and Bridge

conference paper

Czech

The paper is focused on monitoring of the interaction between rail and bridge characterized by a large expansion length. The bridge is situated close to the Czech - Austria state border in the international rail line. The presumptions and values used for the static parameter analysis were necessary to evaluate by data of real bridge and rail performance. Monitoring of the Znojmo viaduct includes a continual measurement of ballast pressure on bridge trough divider at the end of bridge with movable bearers, strain in the structure of this bridge ballast trough divider, thermic expansion of the bridge steel structure relatively to abutments wall, shift of rails relatively to the bridge structure, the strain in rails on the bridge, temperature of the bridge structure, rails and air. Monitoring also includes a surveying of longitudinal displacements of the track length on the bridge and its vicinity by terrestrial and satellite geodetic methods. Investigations also comprised a measurement of expansion joints settings. The monitoring lasted two years from September of 2009 since September of 2011. The longitudinal displacements which were investigated by the continual monitoring and geodetic surveying provide a figure about real bridge-rail interaction due to temperature influences. The basic qualitative conclusion is that the track on bridge does not respond to continuous welded rail behaviour. The track generally follows the bridge expansion. The equivalent coefficient of thermic expansion was evaluated in the value of 9,7.10-6 K-1 is significantly lower than the value of thermic expansion coefficient for steel as structural material. The disproportion between rail and bridge temperature in daily cycles and different thermic expansion behaviour causes longitudinal forces in the track. These forces are transferred besides other on the closing trough divider. So the ballast pressure and consequently stresses in the divider are subjected to the daily temperature cycles. The extreme values of pressure in ballast are caused by impact load during train passages. The impact loads probably originate from flat wheels. The extreme pressure values, which are in a range 300 – 500 kPa, lead to the deterioration of the ballast. A reconsolidation of ballast during seasons and especially impact loads can conclude into undesirable settlement of the track at the end of bridge and consequently to track quality deterioration. Future analyses should be focused on the comparison between the experience which is included into the regulation of Czech Railway Infrastructure Administration and new calculation results. The solving of potential disproportion is a basic task that to be solved would help to improve track quality on bridges and reduce maintenance.

The paper is focused on monitoring of the interaction between rail and bridge characterized by a large expansion length. The bridge is situated close to the Czech - Austria state border in the international rail line. The presumptions and values used for the static parameter analysis were necessary to evaluate by data of real bridge and rail performance. Monitoring of the Znojmo viaduct includes a continual measurement of ballast pressure on bridge trough divider at the end of bridge with movable bearers, strain in the structure of this bridge ballast trough divider, thermic expansion of the bridge steel structure relatively to abutments wall, shift of rails relatively to the bridge structure, the strain in rails on the bridge, temperature of the bridge structure, rails and air. Monitoring also includes a surveying of longitudinal displacements of the track length on the bridge and its vicinity by terrestrial and satellite geodetic methods. Investigations also comprised a measurement of expansion joints settings. The monitoring lasted two years from September of 2009 since September of 2011. The longitudinal displacements which were investigated by the continual monitoring and geodetic surveying provide a figure about real bridge-rail interaction due to temperature influences. The basic qualitative conclusion is that the track on bridge does not respond to continuous welded rail behaviour. The track generally follows the bridge expansion. The equivalent coefficient of thermic expansion was evaluated in the value of 9,7.10-6 K-1 is significantly lower than the value of thermic expansion coefficient for steel as structural material. The disproportion between rail and bridge temperature in daily cycles and different thermic expansion behaviour causes longitudinal forces in the track. These forces are transferred besides other on the closing trough divider. So the ballast pressure and consequently stresses in the divider are subjected to the daily temperature cycles. The extreme values of pressure in ballast are caused by impact load during train passages. The impact loads probably originate from flat wheels. The extreme pressure values, which are in a range 300 – 500 kPa, lead to the deterioration of the ballast. A reconsolidation of ballast during seasons and especially impact loads can conclude into undesirable settlement of the track at the end of bridge and consequently to track quality deterioration. Future analyses should be focused on the comparison between the experience which is included into the regulation of Czech Railway Infrastructure Administration and new calculation results. The solving of potential disproportion is a basic task that to be solved would help to improve track quality on bridges and reduce maintenance.

rail bridge interaction, bridge expansion, geodetic surveying, bridge monitoring, expansion joints, continuous welded rail

rail bridge interaction, bridge expansion, geodetic surveying, bridge monitoring, expansion joints, continuous welded rail

PLÁŠEK, O.; ŠVÁBENSKÝ, O.; VALENTA, M.

2012

18. 4. 2012

Civil-Comp Press

Stirlingshire, UK

978-1-905088-53-9

Proceedings of the Fist International Conference on Railway Technology: Research, Development and Maintenance

49

63

14