도시철도 차량의 사행동을 고려한 강아치 철도교의 동적응답

A railway bridge has both a vertical load distribution and a lateral load distribution with size and direction that change according to the train movement. Lateral loads have a variety of causes, and each of them is linked and shows a complex response. Due to these characteristics, design standards stipulate equivalent lateral loads regardless of the type of bridge. In railway bridge design, dynamic analysis is performed based on the vertical load, but static analysis is used for the lateral load, and lateral vibration regulations are insufficient. The purpose of this study is to present a model for the analysis of snake-like motion for a steel-arch railway bridge and to analyze the effects and dynamic responses through bridge/train interaction analysis for urban railway vehicles. To this end, the wavelength was selected as a parameter according to the train speed. A snake-like motion model was made with the rail deviation, initial lateral force, phase difference, and longitudinal friction coefficient of the rail as random variables. The dynamic responses were analyzed using a time integration method. Twelve train speeds of up to 120 km/h were applied with intervals of 10 km/h. In the result of the numerical analysis, the natural vibration mode was lateral, and lateral deformation occurred preferentially in the primary mode. The lateral displacement in the center of a girder was 0.67 mm when the snake-like motion was ignored, but when considering the snake-like motion, up to 4.7 mm of displacement was generated at a speed of 120 km/h, which is an increase by about seven times. This displacement is equivalent to about twice the static lateral displacement of 2.4 mm due to an equivalent lateral load. In general, as the speed increases, the lateral displacement when considering snake-like motion also increases. The lateral displacement according to the wavelength change of the snake-like motion model also increases rapidly at a specific speed. The wavelength change and speed of the rapid change in the lateral displacement response distribution are linked to the behavior characteristics of the railway bridge, so the slope characteristics should be considered for each bridge model. In particular, in railway bridge design dominated by the lateral behavior mode, dynamic responses need to be analyzed while considering snake-like motion.