# Track-Bridge Interaction of CWR on Chinese Large-Span Bridge of High-Speed Railway
## 2 Research Model of Track-Bridge Interaction  
### Research Model in Code  
From 1964 to 1984, the Office for Research and Experiments (ORE) of the International Union of Railways completed a series of research projects on the track-bridge interaction involving eight countries [4; 5]. The research results can not only be applied to ordinary railways, but also to high-speed railways from 160 to 350 km/h.  
Special regulations for bridges on new railway trunk lines (DS899/59) [6] promulgated by the federal administration of German Railway in 1985 were specially formulated for Shinkansen bridges with a speed of 250 km/h and an actual operating speed of no less than 200 km/h, which collect a large number of scientific research and test results on high-speed railway bridges and lines in the Federal Republic of Germany. It is recommended to use a tension and compression bar or bending beam to simulate the longitudinal resistance of the line. When the length of the beam body is not more than 50 m, at least one connecting rod should be set every 10 m, and when the length of the beam body is greater than 50 m, at least one connecting rod should be set every 5 m. The necessary length of rail on the subgrade section at both ends shall be greater than \(l_{0}+40\) m (\(l_{0}\) is the average span of the beam). The model cannot be used to analyze the longitudinal effect of the beam.  
In 2001, UIC issued the Track/Bridge Interaction Recommendations for Calculations (UIC774-3) [7], based on the German code. The code combines the engineering experience and research results of European countries in the construction of high-speed railway, improves the checking calculation standard of CWR on bridges, and uses simplified formula to estimate the longitudinal force of CWR on the constant cross-section beam bridge and the force on the bridge excitation platform. It is suggested that the longitudinal nonlinear spring be used to simulate the line resistance. The distance from the neutral axis of the beam to the track and the support can be simulated by the plate element or the beam element with a rigid arm. The rail length of the subgrade section should be at least 100 m. For the ordinary beam bridge, the detailed structure of the substructure can be ignored and replaced by the linear spring.  
In 2003, \"traffic loads on bridges\", the second part of Eurocode I: Actions on Structures (BS EN 1991-2:2003) [8], was published by the European Committee for Standardization (hereinafter referred to as \"Eurocode\"), which introduces the principle and checking conditions of the track-bridge interaction.  
The Code for Design of Railway Continuous Welded Rail [2] edited by the fourth Railway Research Institute has passed the Ministry's examination. Based on the results of a large number of model tests and field tests carried out on railways by Chinese universities and scientific research institutions, and with reference to UIC specifications and other foreign research results, the design parameters such as line resistance were modified, and the design methods of CWR in tunnels, turnout areas, and special sections were supplemented.