What is a CWR track on bridge?
CWR track on bridge is a seamless track laid on a bridge. Since 1963, China has laid CWR tracks on various types of bridges with small and medium spans (simply supported beams, continuous beams, trusses, ballasted and ballastless bridges), and conducted a large number of experimental studies on the principle of beam-rail interaction of CWR tracks on bridges, involving the longitudinal force action law of CWR tracks on various types of bridges, as well as the influence of various factors such as bridge pier top displacement (high pier), and established the calculation principle and method of expansion and contraction additional force and deflection additional force of CWR tracks on bridges, laying the foundation for China to lay CWR tracks on bridges.
In addition to being affected by train dynamic loads, temperature forces, braking forces, etc., CWR tracks on bridges are also affected by the beam-rail interaction force generated by the expansion or deflection deformation of the bridge - the longitudinal additional force. The additional longitudinal force increases the stress of the rails, reacts to the bridge, and acts on the piers through the bridge. In addition, once the seamless rail on the bridge breaks, it will not only endanger driving safety, but also generate additional force due to the broken rail, which will act on the pier through the bridge span structure.
Therefore, when designing the seamless rail on the bridge, in order to ensure safety, it is necessary to consider the combined action of the above-mentioned forces to ensure that the rail, bridge span structure and pier meet their respective strength conditions, stability conditions and rail gap conditions.
In the calculation model, a beam unit with a rigid arm is usually used to simulate the bridge, and a nonlinear spring is used to simulate the longitudinal resistance of the line. This model has been verified by experiments [2]. Based on this model, Chinese scholars have calculated and analyzed the seamless rails on high-speed railway simply supported beams, continuous beams, rigid frame bridges, arch bridges, cable-stayed bridges and other bridges.
