Analysis of Longitudinal Coupling of Turnout on Large-Span Tied Arch Bridges and Vehicle Running Performance

To meet the engineering requirements of laying welded turnouts on tied arch bridges, the longitudinal and lateral-vertical coupling vibration models were built based on the interaction principles of turnout-bridge and coupling dynamics of vehicle-turnout-bridge. Taking an example of a 205 m continuous beam bridge on a new passenger dedicated line, three bridge types and nine kinds of layouts in total were involved to analyze the coupling characteristics of the turnout-bridge system and vehicle running performance. The turnout-bridge longitudinal interaction shows that the temperature span has a great influence on the longitudinal deformation of the welded turnouts. And the disciplines of rail additional expansion and contraction forces of different bridge types are the same, but the force values are different. For the Neilson rigid-frame arch bridge plans, the rail additional expansion and contraction forces, relative displacements between the tip of switch rail and stock rail, relative displacements between the tip of nose rail and stock rail, and rail break are all minimum. However, for the large-span continuous beam-arch bridges, the corresponding values are maximum. As to laying welded turnouts on tied arch bridges, the relative displacement between the stock rail at switch machine and bridge is an important factor in selecting the optimal plan. The vehicle running performance analysis shows that the vertical dynamic displacement of Neilson rigid-frame arch bridge is relatively large, and the rate of wheel load reduction exceeds the limit in an instant. In contrast, for the small-span continuous beam bridge, the dynamic displacement is only 1.33 mm, vehicles have a good running performance in safety and comfort, and the maximum lateral acceleration of the car body is only 0.035g.